2024/04/16 更新

写真a

ツボイ ヨウコ
坪井 陽子
TSUBOI Yohko
所属
理工学部 教授
その他担当機関
理工学研究科物理学専攻博士課程前期課程
理工学研究科物理学専攻博士課程後期課程
連絡先
メールによる問い合わせは《こちら》から
外部リンク

学位

  • 博士(理学) ( 京都大学 )

  • 修士(理学) ( 京都大学 )

学歴

  • 1999年3月
     

    京都大学   理学研究科   物理学・宇宙物理学専攻   博士後期   修了

  • 1996年3月
     

    京都大学   理学研究科   物理学第二専攻   修士   修了

  • 1994年3月
     

    京都大学   理学部   卒業

経歴

  • 2015年4月 -  

    中央大学理工学部教授

  • 2007年4月 - 2015年3月

    中央大学理工学部准教授

  • 2004年4月 - 2007年3月

    中央大学理工学部助教授

  • 2007年 -  

    - 中央大学理工学部准教授

  • 2002年4月 - 2004年3月

    中央大学理工学部専任講師

  • 2001年4月 - 2002年3月

    ペンシルバニア州立大学天文学及び宇宙物理学科リサーチ・アソシエート

  • 1999年4月 - 2001年3月

    日本学術振興会海外特別研究員

  • 1999年 - 2001年

    日本学術振興会海外特別研究員

  • 1996年4月 - 1999年3月

    日本学術振興会特別研究員

  • 1996年 - 1999年

    日本学術振興会特別研究員

▼全件表示

所属学協会

  • アメリカ天文学会

  • 日本天文学会

  • 高エネルギー宇宙物理連絡会

研究分野

  • 自然科学一般 / 天文学

論文

  • X-ray/Hα scaling relationships in stellar flares 査読

    Kawai, Hiroki, Tsuboi, Yohko, search by orcid, Iwakiri, Wataru B, search by orcid, Maeda, Yoshitomo, Katsuda, Satoru, search by orcid, Sasaki, Ryo, Kohara, Junya, MAXI TEAM

    Publications of the Astronomical Society of Japan   74 ( 2 )   477 - 487   2022年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Oxford University Press  

    researchmap

  • Detailed design of the science operations for the XRISM mission 査読

    Terada Yukikatsu

    Journal of Astronomical Telescopes, Instruments, and Systems   7 ( 3 )   2021年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP Publishing  

    DOI: 10.1117/1.JATIS.7.3.037001

    Web of Science

    researchmap

  • Erratum: Optical and X-ray observations of stellar flares on an active M dwarf AD Leonis with Seimei Telescope, SCAT, NICER, and OISTER 査読

    Namekata, Kosuke

    Publications of the Astronomical Society of Japan   73 ( 2 )   485 - 485   2021年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    DOI: 10.1093/pasj/psab013

    Web of Science

    researchmap

  • The RS CVn-type Star GT Mus Shows Most Energetic X-Ray Flares Throughout the 2010s 査読

    Sasaki, Ry

    The Astrophysical Journal Letters   910 ( 1 )   13 - 25   2021年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    DOI: 10.3847/1538-4357/abde38

    researchmap

    その他リンク: https://iopscience.iop.org/article/10.3847/1538-4357/abde38/pdf

  • Detail plans and preparations for the science operations of the XRISM mission

    Yukikatsu Terada, Matthew P. Holland, Michael Loewenstein, Makoto S. Tashiro, Hiromitsu Takahashi, Masayoshi Nobukawa, Tsunefumi Mizuno, Takayuki Tamura, Shin'ichiro Uno, Shin Watanabe, Chris Baluta, Laura Burns, Ken Ebisawa, Satoshi Eguchi, Yasushi Fukazawa, Katsuhiro Hayashi, Ryo Iizuka, Satoru Katsuda, Takao Kitaguchi, Aya Kubota, Eric D. Miller, Koji Mukai, Shinya Nakashima, Kazuhiro Nakazawa, Hirokazu Odaka, Masanori Ohno, Naomi Ota, Rie Sato, Yasuharu Sugawara, Megumi Shidatsu, Tsubasa Tamba, Atsushi Tanimoto, Yuichi Terashima, Yohko Tsuboi, Yuusuke Uchida, Hideki Uchiyama, Shigeo Yamauchi, Tahir Yaqoob

    Space Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray   11444   2020年12月

     詳細を見る

    掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE  

    © 2020 SPIE The XRISM is the X-ray astronomical mission led by JAXA/NASA/ESA with international participation, plan to be launched in 2022 (Japanese fiscal year), to quickly recover the high-resolution X-ray spectroscopy of astrophysical objects using the micro-calorimeter array after the failure of Hitomi. To enhance the scientific outputs of the mission, the Science Operations Team (SOT) is structured independently from the instrument teams and the mission operation team (MOT). The responsibilities of the SOT are summarized into four categories: 1) Guest observer program and data distributions, 2) Distribution of the analyses software and calibration database, 3) Guest observer supporting activities, and 4) the performance verification and optimization (PVO) activities. Before constructing the Operations Concept of the XRISM mission, the lessons on the Science Operations learned from the past Japanese X-ray missions (ASCA, Suzaku, and Hitomi) are reviewed, and 16 kinds of lessons are identified by the above categories: lessons on the importance of avoiding nonpublic (“animal”) tools, coding quality of public tools both on the engineering viewpoint and the calibration accuracy, tight communications with instrument teams and operations team, well-defined task division between scientists and engineers etc. Among these lessons, a) importance of the early preparations of the operations from the ground stage, b) construction of the independent team for the Science Operations from the instrument developments, and c) operations with well-defined duties by appointed members are recognized as the key lessons for XRISM. Then, i) the task division between the Mission and Science Operations and ii) the subgroup structure within the XRISM team are defined in detail as the XRISM Operations Concept. Then, following the Operations Concept, the detail plan of the Science Operations is designed as follows. The Science Operations tasks are shared among Japan, US, and Europe operated by three centers, the Science Operations Center (SOC) at JAXA, the Science Data Center (SDC) at NASA, and European Space Astronomy Centre (ESAC) at ESA. The SOT is defined as a combination of the SOC and SDC; the SOC is designed to perform tasks close to the spacecraft operations, such as spacecraft planning of science targets, quick-look health checks, pre-pipeline data processing, etc., and the SDC covers the tasks on the data calibration processing (pipeline processing), maintenance of the analysis tools etc. The data-archive and users-support activities are planned to be covered both by the SOC and SDC. Finally, the details of the Science Operations tasks and the tools for the Science Operations are also described in this paper. This information would be helpful for a construction of Science Operations of future X-ray missions.

    DOI: 10.1117/12.2560861

    Scopus

    researchmap

  • The XRISM science data center: optimizing the scientific return from a unique x-ray observatory

    Michael Loewenstein, Robert S. Hill, Matthew P. Holland, Eric D. Miller, Tahir Yaqoob, Trisha F. Doyle, Patricia L. Hall, Efrem Braun, Christopher J. Baluta, Koji Mukai, Yukikatsu Terada, Makoto S. Tashiro, Hiromitsu Takahashi, Masayoshi Nobukawa, Tsunefumi Mizuno, Takayuki Tamura, Shin'ichiro Uno, Shin Watanabe, Ken Ebisawa, Satoshi Eguchi, Yasushi Fukazawa, Ryo Iizuka, Satoru Katsuda, Takao Kitaguchi, Aya Kubota, Shinya Nakashima, Kazuhiro Nakazawa, Hirokazu Odaka, Masanori Ohno, Naomi Ota, Rie Sato, Yasuharu Sugawara, Megumi Shidatsu, Tsubasa Tamba, Yuichi Terashima, Yohko Tsuboi, Yuusuke Uchida, Hideki Uchiyama, Shigeo Yamauchi

    Space Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray   11444   2020年12月

     詳細を見る

    掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE  

    © 2020 SPIE The X-Ray Imaging and Spectroscopy Mission, XRISM, is currently scheduled to launch in 2022 with the objective of building on the brief, but significant, successes of the ASTRO-H (Hitomi) mission in solving outstanding astrophysical questions using high resolution X-ray spectroscopy. The XRISM Science Operations Team (SOT) consists of the JAXA-led Science Operations Center (SOC) and NASA-led Science Data Center (SDC), which work together to optimize the scientific output from the Resolve high-resolution spectrometer and the Xtend wide-field imager through planning and scheduling of observations, processing and distribution of data, development and distribution of software tools and the calibration database (CaldB), support of ground and in-flight calibration, and support of XRISM users in their scientific investigations of the energetic universe. Here, we summarize the roles and responsibilities of the SDC and its current status and future plans. The Resolve instrument poses particular challenges due to its unprecedented combination of high spectral resolution and throughput, broad spectral coverage, and relatively small field-of-view and large pixel-size. We highlight those challenges and how they are being met.

    DOI: 10.1117/12.2560840

    Scopus

    researchmap

  • Optical and X-ray observations of stellar flares on an active M dwarf AD Leonis with the Seimei Telescope, SCAT, NICER, and OISTER 査読

    Namekata, Kosuke

    Publications of the Astronomical Society of Japan   72 ( 4 )   15   2020年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    DOI: 10.1093/pasj/psaa051

    researchmap

  • Inverse First Ionization Potential Effects in Giant Solar Flares Found from Earth X-Ray Albedo with Suzaku/XIS 査読

    Katsuda, Sator

    The Astrophysical Journal Letters   891 ( 2 )   13 - 126   2020年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    DOI: 10.3847/1538-4357/ab7207

    researchmap

    その他リンク: https://iopscience.iop.org/article/10.3847/1538-4357/ab7207

  • Detection of polarized gamma-ray emission from the Crab nebula with the Hitomi Soft Gamma-ray Detector 査読

    Hitomi Collaboratio

    Publications of the Astronomical Society of Japan   70 ( 6 )   2018年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    DOI: 10.1093/pasj/psy118

    Web of Science

    researchmap

  • Extremely Dense Cores associated with Chandra Sources in Ophiuchus A: Forming Brown Dwarfs Unveiled? 査読

    Ryohei Kawabe, Chihomi Hara, Fumitaka Nakamura, Kazuya Saigo, Takeshi Kamazaki, Yoshito Shimajiri, Kengo Tomida, Shigehisa Takakuwa, Yohko Tsuboi, Masahiro N. Machida, James Di Francesco, Rachel Friesen, Naomi Hirano, Yumiko Oasa, Motohide Tamura, Yoichi Tamura, Takashi Tsukagoshi, David Wilner

    ASTROPHYSICAL JOURNAL   866 ( 2 )   2018年10月

     詳細を見る

    On the basis of various data such as ALMA, JVLA, Chandra, {\it Herschel}, and
    {\it Spitzer}, we confirmed that two protostellar candidates in Oph-A are bona
    fide protostars or proto-brown dwarfs (proto-BDs) in extremely early
    evolutionary stages. Both objects are barely visible across infrared (IR, i.e.,
    near-IR to far-IR) bands. The physical nature of the cores is very similar to
    that expected in first hydrostatic cores (FHSCs), objects theoretically
    predicted in the evolutionary phase prior to stellar core formation with gas
    densities of $\sim$ 10$^{11-12}$ cm$^{-3}$. This suggests that the evolutionary
    stage is close to the FHSC formation phase. The two objects are associated with
    faint X-ray sources, suggesting that they are in very early phase of stellar
    core formation with magnetic activity. In addition, we found the CO outflow
    components around both sources which may originate from the young outflows
    driven by these sources. The masses of these objects are calculated to be $\sim
    0.01-0.03$ $M_\odot$ from the dust continuum emission. Their physical
    properties are consistent with that expected from the numerical model of
    forming brown dwarfs. These facts (the X-ray detection, CO outflow association,
    and FHSC-like spectral energy distributions) strongly indicate that the two
    objects are proto-BDs or will be in the very early phase of protostars which
    will evolve more massive protostars if they gain enough mass from the
    surroundings. The ages of these two objects are likely to be within $\sim 10^3$
    years after the protostellar core (or second core) formation, taking into
    account the outflow dynamical times ($\lesssim$ 500 yrs).

    DOI: 10.3847/1538-4357/aae153

    Web of Science

    arXiv

    researchmap

  • The 7-year MAXI/GSC X-Ray Source Catalog in the High Galactic Latitude Sky (3MAXI) 査読

    Kawamuro, T

    The Astrophysical Journal Letters   238 ( 2 )   15 - 32   2018年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    DOI: 10.3847/1538-4365/aad1ef

    researchmap

    その他リンク: https://iopscience.iop.org/article/10.3847/1538-4365/aad1ef

  • Hitomi X-ray observation of the pulsar wind nebula G21.5-0.9 査読

    Hitomi Collaboratio

    Publications of the Astronomical Society of Japan   70 ( 3 )   2018年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    DOI: 10.1093/pasj/psy027

    researchmap

  • Hitomi (ASTRO-H) X-ray Astronomy Satellite 査読

    Takahashi, Tadayuki

    Journal of Astronomical Telescopes   4 ( 2 )   2018年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1117/1.JATIS.4.2.021402

    Web of Science

    researchmap

  • The 7-year MAXI/GSC Source Catalog of the Low-Galactic-latitude Sky (3MAXI) 査読

    Hori, T, Shidatsu, M, Ueda, Y, Kawamuro, T, Morii, M, Nakahira, S, Isobe, N, Kawai, N, Mihara, T, Matsuoka, M, Morita, T, Nakajima, M, Negoro, H, Oda, S, Sakamoto, T, Serino, M, Sugizaki, M, Tanimoto, A, Tomida, H, Tsuboi, Y. Tsunemi, H, Ueno, S, Yamaoka, K, Yamada, S, Yoshida, A, Iwakiri, W, Kawakubo, Y, Sugawara, Y, Sugita, S, Tachibana, Y, Yoshii, T

    Astrophysical Journal   235 ( 1 )   40   2018年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    DOI: 10.3847/1538-4365/aaa89c

    Web of Science

    researchmap

  • Glimpse of the highly obscured HMXB IGR J16318-4848 with Hitomi 査読

    Hitomi Collaboratio

    Publications of the Astronomical Society of Japan   70 ( 2 )   2018年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    DOI: 10.1093/pasj/psx154

    researchmap

  • Hitomi observations of the LMC SNR N 132 D: Highly redshifted X-ray emission from iron ejecta 査読

    Hitomi Collaboratio

    Publications of the Astronomical Society of Japan   70 ( 2 )   2018年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    J-GLOBAL

    researchmap

  • Hitomi X-ray studies of giant radio pulses from the Crab pulsar 査読

    Hitomi Collaboratio

    Publications of the Astronomical Society of Japan   70 ( 2 )   2018年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    J-GLOBAL

    researchmap

  • Search for thermal X-ray features from the Crab nebula with the Hitomi soft X-ray spectrometer 査読

    Hitomi Collaboratio

    Publications of the Astronomical Society of Japan   70 ( 2 )   2018年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    J-GLOBAL

    researchmap

  • Hitomi observation of radio galaxy NGC 1275: The first X-ray microcalorimeter spectroscopy of Fe-Kα line emission from an active galactic nucleusobservations of the Perseus cluster with Hitomi 査読

    Hitomi Collaboratio

    Publications of the Astronomical Society of Japan   70 ( 2 )   2018年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    J-GLOBAL

    researchmap

  • Atomic data and spectral modeling constraints from high-resolution X-ray observations of the Perseus cluster with Hitomi 査読

    Hitomi Collaboratio

    Publications of the Astronomical Society of Japan   70 ( 2 )   2018年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    J-GLOBAL

    researchmap

  • Measurements of resonant scattering in the Perseus Cluster core with Hitomi SXS 査読

    Hitomi Collaboratio

    Publications of the Astronomical Society of Japan   70 ( 2 )   2018年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    J-GLOBAL

    researchmap

  • Temperature structure in the Perseus cluster core observed with Hitomi 査読

    Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W, Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W, Blandford, Roger, Brenneman, Laura W, Brown, Gregory, V, Bulbul, Esra, Cackett, Edward M, Chernyakova, Maria, Chiao, Meng P, Coppi, Paolo S, Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P, den Herder, Jan-Willem, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E, Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C, Ferrigno, Carlo, Foster, Adam R, Fujimoto, Ryuichi, Fukazawa, Yasushi, Furukawa, Maki, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C, Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M, Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashida, Kiyoshi, Hiraga, Junko S, Hornschemeier, Ann, Hoshino, Akio, Hughes, John P, Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Kato, Yuichi, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L, Kilbourne, Caroline A, Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A, Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A, Limousin, Olivier, Loewenstein, Michael, Long, Knox S, Lumb, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R, Mehdipour, Missagh, Miller, Eric D, Miller, Jon M, Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F, Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Norukawa, Kumiko K, Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stephane, Petre, Robert, Pinto, Ciro, Porter, Frederick S, Pottschmidt, Katja, Reynolds, Christopher S, Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemitsos, Peter J, Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K, Soong, Yang, Stawarz, Lukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shinichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T, Tashiro, Makoto S, Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto, Masahiro, Tsunemi, Hiroshi, Tsuru, Take

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   70 ( 2 )   2018年3月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS  

    The present paper explains the temperature structure of X-ray emitting plasma in the core of the Perseus cluster based on 1.8-20.0 keV data obtained with the Soft X-ray Spectrometer (SXS) on board the Hitomi Observatory. A series of four observations was carried out, with a total effective exposure time of 338 ks that covered a central region of similar to 7' in diameter. SXS was operated with an energy resolution of similar to 5 eV (full width at half maximum) at 5.9 keV. Not only fine structures of K-shell lines in He-like ions, but also transitions from higher principal quantum numbers were clearly resolved from Si through Fe. That enabled us to perform temperature diagnostics using the line ratios of Si, S, Ar, Ca, and Fe, and to provide the first direct measurement of the excitation temperature and ionization temperature in the Perseus cluster. The observed spectrum is roughly reproduced by a single-temperature thermal plasma model in collisional ionization equilibrium, but detailed line-ratio diagnostics reveal slight deviations from this approximation. In particular, the data exhibit an apparent trend of increasing ionization temperature with the atomic mass, as well as smal

    DOI: 10.1093/pasj/psy004

    researchmap

  • Atmospheric gas dynamics in the Perseus cluster observed with Hitomi 査読

    Aharonian, Felix, Akamatsu, Hiroki, Akimoto, Fumie, Allen, Steven W, Angelini, Lorella, Audard, Marc, Awaki, Hisamitsu, Axelsson, Magnus, Bamba, Aya, Bautz, Marshall W, Blandford, Roger, Brenneman, Laura W, Brown, Gregory, V, Bulbul, Esra, Cackett, Edward M, Canning, Rebecca E. A, Chernyakova, Maria, Chiao, Meng P, Coppi, Paolo S, Costantini, Elisa, de Plaa, Jelle, de Vries, Cor P, den Herder, Jan-Willem, Done, Chris, Dotani, Tadayasu, Ebisawa, Ken, Eckart, Megan E, Enoto, Teruaki, Ezoe, Yuichiro, Fabian, Andrew C, Ferrigno, Carlo, Foster, Adam R, Fujimoto, Ryuichi, Fukazawa, Yasushi, Furuzawa, Akihiro, Galeazzi, Massimiliano, Gallo, Luigi C, Gandhi, Poshak, Giustini, Margherita, Goldwurm, Andrea, Gu, Liyi, Guainazzi, Matteo, Haba, Yoshito, Hagino, Kouichi, Hamaguchi, Kenji, Harrus, Ilana M, Hatsukade, Isamu, Hayashi, Katsuhiro, Hayashi, Takayuki, Hayashi, Tasuku, Hayashida, Kiyoshi, Hiraga, Junko S, Hornschemeier, Ann, Hoshino, Akio, Hughes, John P, Ichinohe, Yuto, Iizuka, Ryo, Inoue, Hajime, Inoue, Shota, Inoue, Yoshiyuki, Ishida, Manabu, Ishikawa, Kumi, Ishisaki, Yoshitaka, Iwai, Masachika, Kaastra, Jelle, Kallman, Tim, Kamae, Tsuneyoshi, Kataoka, Jun, Katsuda, Satoru, Kawai, Nobuyuki, Kelley, Richard L, Kilbourne, Caroline A, Kitaguchi, Takao, Kitamoto, Shunji, Kitayama, Tetsu, Kohmura, Takayoshi, Kokubun, Motohide, Koyama, Katsuji, Koyama, Shu, Kretschmar, Peter, Krimm, Hans A, Kubota, Aya, Kunieda, Hideyo, Laurent, Philippe, Lee, Shiu-Hang, Leutenegger, Maurice A, Limousin, Olivier, Loewenstein, Michael, Long, Knox S, Lumr, David, Madejski, Greg, Maeda, Yoshitomo, Maier, Daniel, Makishima, Kazuo, Markevitch, Maxim, Matsumoto, Hironori, Matsushita, Kyoko, McCammon, Dan, McNamara, Brian R, Mehdipour, Missagh, Miller, Eric D, Miller, Jon M, Mineshige, Shin, Mitsuda, Kazuhisa, Mitsuishi, Ikuyuki, Miyazawa, Takuya, Mizuno, Tsunefumi, Mori, Hideyuki, Mori, Koji, Mukai, Koji, Murakami, Hiroshi, Mushotzky, Richard F, Nakagawa, Takao, Nakajima, Hiroshi, Nakamori, Takeshi, Nakashima, Shinya, Nakazawa, Kazuhiro, Norukawa, Kumiko K, Nobukawa, Masayoshi, Noda, Hirofumi, Odaka, Hirokazu, Ohashi, Takaya, Ohno, Masanori, Okajima, Takashi, Ota, Naomi, Ozaki, Masanobu, Paerels, Frits, Paltani, Stephane, Petre, Robert, Pinto, Ciro, Porter, Frederick S, Pottschmidt, Katja, Reynolds, Christopher S, Safi-Harb, Samar, Saito, Shinya, Sakai, Kazuhiro, Sasaki, Toru, Sato, Goro, Sato, Kosuke, Sato, Rie, Sawada, Makoto, Schartel, Norbert, Serlemitsos, Peter J, Seta, Hiromi, Shidatsu, Megumi, Simionescu, Aurora, Smith, Randall K, Soong, Yang, Stawarz, Lukasz, Sugawara, Yasuharu, Sugita, Satoshi, Szymkowiak, Andrew, Tajima, Hiroyasu, Takahashi, Hiromitsu, Takahashi, Tadayuki, Takeda, Shin'ichiro, Takei, Yoh, Tamagawa, Toru, Tamura, Takayuki, Tanaka, Keigo, Tanaka, Takaaki, Tanaka, Yasuo, Tanaka, Yasuyuki T, Tashiro, Makoto S, Tawara, Yuzuru, Terada, Yukikatsu, Terashima, Yuichi, Tombesi, Francesco, Tomida, Hiroshi, Tsuboi, Yohko, Tsujimoto

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   70 ( 2 )   2018年3月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS  

    Extending the earlier measurements reported in Hitomi collaboration (2016, Nature, 535, 117), we examine the atmospheric gas motions within the central 100 kpc of the Perseus cluster using observations obtained with the Hitomi satellite. After correcting for the point spread function of the telescope and using optically thin emission lines, we find that the line-of-sight velocity dispersion of the hot gas is remarkably low and mostly uniform. The velocity dispersion reaches a maxima of approximately 200 km s(-1) toward the central active galactic nucleus (AGN) and toward the AGN inflated northwestern "ghost" bubble. Elsewhere within the observed region, the velocity dispersion appears constant around 100 km s(-1). We also detect a velocity gradient with a 100 km s(-1) amplitude across the cluster core, consistent with large-scale sloshing of the core gas. If the observed gas motions are isotropic, the kinetic pressure support is less than 10% of the thermal pressure support in the cluster core. The well-resolved, optically thin emission lines have Gaussian shapes, indicating that the turbulent driving scale is likely below 100 kpc, which is consistent with the size of the

    DOI: 10.1093/pasj/psx138

    researchmap

  • Solar abundance ratios of the iron-peak elements in the Perseus cluster 査読

    Hitomi Collaboration, 頭著者

    Nature   551 ( 7681 )   478 - 480   2017年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Nature Publishing Group  

    DOI: 10.1038/nature24301

    Web of Science

    researchmap

  • Multi-messenger Observations of a Binary Neutron Star Merger 査読

    Abbott, B, 筆頭著者

    Publications of the Astronomical Society of Japan   848 ( 2 )   59   2017年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    DOI: 10.3847/2041-8213/aa91c9

    Web of Science

    researchmap

  • Hitomi Constraints on the 3.5 keV Line in the Perseus Galaxy Cluster 査読

    Aharonian, F, A

    The Astrophysical Journal Letters   837 ( 1 )   2017年3月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    DOI: 10.3847/2041-8213/aa61fa

    Web of Science

    researchmap

  • A Universal Correlation between the Duration and the X-ray Luminosity in stellar flares 査読

    Tsuboi, Y, Sasaki, R, Sugawara, Y, Matsuoka, M

    Acta Polytechnica CTU Proceedings   2017年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Czech Technical University in Prague  

    researchmap

  • TWO DISTINCT-ABSORPTION X-RAY COMPONENTS FROM TYPE IIn SUPERNOVAE: EVIDENCE FOR ASPHERICITY IN THE CIRCUMSTELLAR MEDIUM 査読

    Katsuda, Satoru, Maeda, Keiichi, Bamba, Aya, Terada, Yukikatsu, Fukazawa, Yasushi, Kawabata, Koji, Ohno, Masanori, Sugawara, Yasuharu, Tsuboi, Yohko, Immler, Stefan

    ASTROPHYSICAL JOURNAL   832 ( 2 )   2016年12月

     詳細を見る

    掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We present multi-epoch X-ray spectral observations of three Type IIn supernovae (SNe), SN 2005kd, SN 2006jd, and SN 2010jl, acquired with Chandra, XMM-Newton, Suzaku, and Swift. Previous extensive X-ray studies of SN. 2010jl have revealed that X-ray spectra are dominated by thermal emission, which likely arises from a hot plasma heated by a forward shock propagating into a massive circumstellar medium (CSM). Interestingly, an additional soft X-ray component was required to reproduce the spectra at a period of similar to 1-2 years after the SN explosion. Although this component is likely associated with the SN, its origin remained an open question. We find a similar, additional soft X-ray component from the other two SNe IIn as well. Given this finding, we present a new interpretation for the origin of this component; it is thermal emission from a forward shock essentially identical to the hard X-ray component, but directly reaches us from a void of the dense CSM. Namely, the hard and soft components are responsible for the heavily and moderately absorbed components, respectively. The co-existence of the two components with distinct absorptions as well as the delayed emergence of th

    DOI: 10.3847/0004-637X/832/2/194

    researchmap

  • Large X-ray flares on stars detected with MAXI/GSC: A universal correlation between the duration of a flare and its X-ray luminosity 査読

    Yohko Tsuboi, Kyohei Yamazaki, Yasuharu Sugawara, Atsushi Kawagoe, Soichiro Kaneto, Ryo Iizuka, Takanori Matsumura, Satoshi Nakahira, Masaya Higa, Masaru Matsuoka, Mutsumi Sugizaki, Yoshihiro Ueda, Nobuyuki Kawai, Mikio Morii, Motoko Serino, Tatehiro Mihara, Hiroshi Tomida, Shiro Ueno, Hitoshi Negoro, Arata Daikyuji, Ken Ebisawa, Satoshi Eguchi, Kazuo Hiroi, Masaki Ishikawa, Naoki Isobe, Kazuyoshi Kawasaki, Masashi Kimura, Hiroki Kitayama, Mitsuhiro Kohama, Taro Kotani, Yujin E. Nakagawa, Motoki Nakajima, Hiroshi Ozawa, Megumi Shidatsu, Tetsuya Sootome, Kousuke Sugimori, Fumitoshi Suwa, Hiroshi Tsunemi, Ryuichi Usui, Takayuki Yamamoto, Kazutaka Yamaoka, Atsumasa Yoshida

    Publications of the Astronomical Society of Japan   68 ( 5 )   90   2016年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    © 2016 The Author. Published by Oxford University Press on behalf of the Astronomical Society of Japan. All rights reserved. Twenty-three giant flares from thirteen active stars (eight RS CVn systems, one Algol system, three dMe stars, and one young stellar object) were detected during the first two years of our all-sky X-ray monitoring with the gas propotional counters (GSC) of the Monitor of All-sky X-ray Image (MAXI). The observed parameters of all these MAXI/GSC flares are found to be at the upper ends for stellar flares with the luminosity of 1031-34 erg s-1 in the 2-20 keV band, the emission measure of 1054-57 cm-3, the e-folding time of 1 hr to 1.5 d, and the total radiative energy released during the flare of 1034-39 erg. Notably, the peak X-ray luminosity of 5+4-2 × 1033erg s-1 in the 2-20 keV band was detected in one of the flares on II Peg, which is one of the, or potentially the, largest-ever-observed in stellar flares. X-ray flares were detected from GT Mus, V841 Cen, SZ Psc, and TWA-7 for the first time in this survey. Whereas most of our detected sources are multiple-star systems, two of them are single stars (YZ CMi and TWA-7). Among the stellar sources within 100 pc distance, the MAXI/GSC sources have larger rotation velocities than the other sources. This suggests that the rapid rotation velocity may play a key role in generating large flares. Combining the X-ray flare data of nearby stars and the sun, taken from literature and our own data, we discovered a universal correlation of τ LX0.2 for the flare duration τ and the intrinsic X-ray luminosity LX in the 0.1-100 keV band, which holds for 5 and 12 orders of magnitude in τ and LX, respectively. The MAXI/GSC sample is located at the highest ends of the correlation.

    DOI: 10.1093/pasj/psw081

    Scopus

    researchmap

  • The quiescent intracluster medium in the core of the Perseus cluster 査読

    Hitomi Collaboration, 頭著者

    Nature   535 ( 7610 )   117 - 121   2016年7月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Nature Publishing Group  

    J-GLOBAL

    researchmap

  • The MAXI/GSC Nova-Alert System and results of its first 68 months 査読

    H. Negoro

    Publications of the Astronomical Society of Japan   68 ( SP1 )   24 - S1   2016年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1093/pasj/psw016

    researchmap

  • Development of X-ray spectroscopic polarimetry with bent Si crystals and CFRP substrate 査読

    Ryo Iizuka, Takanori Izumiya, Yohko Tsuboi

    SPACE TELESCOPES AND INSTRUMENTATION 2016: ULTRAVIOLET TO GAMMA RAY   9905   2016年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    The light from celestial objects includes four important quantities; images, time variation, energy spectrum, and polarization. In the field of X-ray astronomy, the capabilities of the former three have remarkably developed. On the other hand, the progress for the polarimetry is considerably delayed because of technical difficulties. In order to make a breakthrough in the field of X-ray polarimetry, we have developed a new type of optics for X-ray polarimetry. The system is collecting Bragg crystal with large area and very high sensitivity for the polarization dedicated to Fe-K lines. We adopt the 400 reflection of Si(100) crystals with high sensitivity for the polarization around Fe-K lines (6 similar to 7 keV), and bent the crystals with the wide X-ray band and high S/N ratio. Furthermore, to install small area of CCD to non-focal plane, it also has the spectroscopic capability with the better resolution than that of general X-ray CCD.
    Our previous development was to bent Si crystals to the cylindrical shape of circle and parabola with the DLC deposition. However, for the better optics for the X-ray polarimetry, the shape should be the paraboloid of revolution to collect X-rays with high S/N ratio. We searched for the method to bent the Si crystals to the shape of the paraboloid of revolution. We devised the method to mold the crystal and the CFRP substrate simultaneously pushed to the sophisticated foundation with the paraboloid of revolution. We developed the prototype of about 8 inch in radius of one-quater size. The crystals was also bent in the circumferential direction. Therefore, the image capability examined with optical parallel beam is 0.6 degree. In this thesis, we discussed the new design for X-ray spectroscopic polarimetry, the evaluation of image capability.

    DOI: 10.1117/12.2231166

    Web of Science

    researchmap

  • Suzaku monitoring of the Wolf-Rayet binary WR 140 around periastron passage: An approach for quantifying the wind parameters 査読

    Sugawara, Yasuharu, Maeda, Yoshitomo, Tsuboi, Yohko, Hamaguchi, Kenji, Corcoran, Michael, Pollock, Andy M. T, Moffat, Anthony F. J, Williams, Peredur M, Dougherty, Sean, Pittard, Julian

    Publications of the Astronomical Society of Japan   67 ( 6 )   2015年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1093/pasj/psv099

    Web of Science

    researchmap

  • MAXI observations of gamma-ray bursts 査読

    M. Serino, 頭著者名

    Publications of the Astronomical Society of Japan   66 ( 5 )   8714 - 87   2014年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1093/pasj/psu063

    researchmap

  • Hyper X-ray flares on active stars detected with MAXI 査読

    Masaya Higa, Yohko Tsuboi, Hitoshi Negoro, Satoshi Nakahira, Hiroshi Tomida, Masaru Matsuoka

    Proceedings of the International Astronomical Union   9 ( S302 )   200 - 201   2014年8月

     詳細を見る

    掲載種別:研究論文(学術雑誌)  

    MAXI started its operation in 2009 August. Owing to its unprecedentedly high sensitivity as an all-sky X-ray monitor and to its capability of real-time data transfer, we have detected 56 strong flares from twenty-one active stars (eleven RS CVn systems, one Algol system, seven dMe stars, one dKe star and one Young Stellar Object). These flares have large X-ray luminosity of 6 × 1030 -5 × 1033 ergs s-1 in the 2-20 keV band. The flares can be thought to be high ends among their own categories. During the flare from AT Mic on 2012 April 18th, one of the largest X-ray luminosities was recorded as a dMe star, 6 × 1032 ergs s -1 in the 2-20 keV band. It is larger than its bolometric luminosity by 4 times. The total energy emitted during the flare is 1036 ergs in the same band. Such total energy can be obtained on large flares from RS CVn system, but not on any other flares from dMe stars. In this proceeding, we report on the present situation in characteristics of hyper X-ray flares on each stellar categories. © International Astronomical Union 2014.

    DOI: 10.1017/S1743921314002075

    Scopus

    researchmap

  • ANNUAL PARALLAX DETERMINATION TOWARD A NEW X-RAY-EMITTING CLASS 0 CANDIDATE WITH THE WATER MASER IN THE NGC 2264 STAR-FORMING REGION 査読

    Tatsuya Kamezaki, Kenji Imura, Toshihiro Omodaka, Toshihiro Handa, Yohko Tsuboi, Takumi Nagayama, Tomoya Hirota, Kazuyoshi Sunada, Hideyuki Kobayashi, James O. Chibueze, Eiji Kawai, Makoto Nakano

    ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES   211 ( 2 )   2014年4月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    In our multi-epoch observation of the star-forming region NGC 2264 with the VLBI Exploration of Radio Astrometry, we detected two water maser features. We have measured the annual parallax of the maser sources for the first time in NGC 2264 and derived 1.356 +/- 0.098 mas, corresponding to the distance of 738(-50)(+57) pc, which is consistent with its previously reported photometric observations. One of the maser features is located near a dust continuum core, CMM4S, positionally corresponding to the X-ray source FMS2-1269 listed in Flaccomio et al. Re-analyzing Chandra X-ray data, we found that FMS2-1269 is still surrounded by a dense envelope of a H-2 column density, 5.4 x 10(23) cm(-2). We suggest that the maser detected near the CMM4S core is most likely associated with the X-ray-emitting Class 0 candidate FMS2-1269. The other maser feature is found to emerge from a high-velocity outflow of 150 km s(-1) and is associated with the 3.6 cm radio continuum source NGC 2264 VLA 3 located close to IRS1.

    DOI: 10.1088/0067-0049/211/2/18

    Web of Science

    researchmap

  • Wide-Field MAXI: soft X-ray transient monitor on the ISS 査読

    Nobuyuki Kawai, Hiroshi Tomida, Yoichi Yatsu, Tatehiro Mihara, Shiro Ueno, Masahi Kimura, Makoto Arimoto, Motoko Serino, Takanori Sakamoto, Hiroshi Tsunemi, Takayoshi Kohmura, Hitoshi Negoro, Yoshihiro Ueda, Mikio Morii, Yohko Tsuboi, Ken Ebisawa, Atsumasa Yoshida

    SPACE TELESCOPES AND INSTRUMENTATION 2014: ULTRAVIOLET TO GAMMA RAY   9144   2014年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    WF-MAXI is a soft X-ray transient monitor proposed for the ISS/JEM. Unlike MAXI, it will always cover a large field of view (20 % of the entire sky) to detect short transients more efficiently. In addition to the various transient sources seen by MAXI, we hope to localize X-ray counterparts of gravitational wave events, expected to be directly detected by Advanced-LIGO, Virgo and KAGRA in late 2010's. The main instrument, the Soft X-ray Large Solid Angle Cameras (SLC) is sensitive in the 0.7-12 keV band with a localization accuracy of similar to 0.1 degrees. The Hard X-ray Monitor (HXM) covers the same sky field in the 20 keV-1 MeV band.

    DOI: 10.1117/12.2057188

    Web of Science

    researchmap

  • Extraordinary Luminous Soft X-Ray Transient MAXI J0158-744 as an Ignition of a Nova on a Very Massive O-Ne White Dwarf 査読

    M. Morii, 頭著者名

    779 ( 2 )   118 - 118   2013年12月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1088/0004-637x/779/2/118

    researchmap

    その他リンク: http://stacks.iop.org/0004-637X/779/i=2/a=118?key=crossref.d6cfdf46d5ae0a9b50ed717d620008c2

  • The 37 Month MAXI/GSC Source Catalog of the High Galactic-Latitude Sky 査読

    K. Hiroi

    207 ( 2 )   36 - 36   2013年8月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1088/0067-0049/207/2/36

    researchmap

    その他リンク: https://iopscience.iop.org/article/10.1088/0067-0049/207/2/36

  • Spectral Evolution of a New X-Ray Transient MAXI J0556-332 Observed by MAXI, Swift, and RXTE 査読

    M. Sugizaki, 頭著者名含

    65 ( 3 )   2013年6月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1093/pasj/65.3.58

    Web of Science

    researchmap

  • Outburst of LS V +44 17 Observed by MAXI and RXTE, and Discovery of a Dip Structure in the Pulse Profile 査読

    R. Usui, 筆頭著者名含

    64 ( 4 )   2012年8月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1093/pasj/64.4.79

    Web of Science

    researchmap

  • A Spectral Study of the Black Hole Candidate XTE J1752-223 in the High/Soft State with MAXI, Suzaku, and Swift 査読

    S. Nakahira, 頭著者

    64 ( 1 )   2012年2月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1093/pasj/64.1.13

    Web of Science

    researchmap

  • Development of bent crystal for imaging polarimetry 査読

    Kota Okada, Takashi Awaya, Yohko Tsuboi, Ryo Iizuka, Naoto Ohtake

    SPACE TELESCOPES AND INSTRUMENTATION 2012: ULTRAVIOLET TO GAMMA RAY   8443   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    We are developing a Bragg crystal polarimeter which has high modulation factor. The point we aim is to bend the crystal; by using bent crystal, we can reflect X-ray emission with broadened energy width, focus it on a small detector, which increases S/N ratio, and obtain imaging capability. We bent Si (100) crystal sheets by depositing Diamond-Like Carbon (DLC) on the backside of reflection surface. They are bent by the residual stress between the DLC and crystal. We can control the curvature by changing the DLC thickness. The angular reflectivity was measured with the line emission at 8.04 keV (Cu-K alpha). We confirmed that the angular width is broadened to 1 degree, which is equivalent to the energy width of 0.5 keV. The integrated reflectivity becomes larger, as the curvature radius of crystal becomes small. The modulation factor of bent Si is 0.74, which is higher than that of the flat Si of 0.51. Having the wide energy band with the high modulation factor, the bent Si crystal can be a new tool for the X-ray polarimeter. We have also made the bent Ge(111) crystal and measured the same performances. The modulation factor of both the flat and the bent Ge were 0.99, when using the 8.04 keV (Cu-K alpha) beam, as we expected. This means that by choosing crystals, we can make efficient observations with aimed energy band. We report the status of our development.

    DOI: 10.1117/12.926053

    Web of Science

    researchmap

  • Bent Si reflector with DLC deposition developed for X-ray imaging polarimetry 査読

    Takashi Awaya, Atsushi Tokuno, Kota Okada, Yohko Tsuboi, Ryo Iizuka, Shingo Kusunoki, Kazuyoshi Misumi

    SUZAKU 2011: EXPLORING THE X-RAY UNIVERSE: SUZAKU AND BEYOND   1427   2012年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    We report a development of a bent crystal for use of X-ray polarimeter. We deposited Diamond-Like Carbon (DLC) on the back side of reflection surface of a Si(400) crystal sheet, and bent the crystal sheet by the residual stress between the DLC and Si. We confirmed that the curvature can be controlled with the thickness of DLC. An angular reflectivity of the crystal was measured with the line emission at 8 keV (Cu-Ka). The angular width is broadened to 2 degree, centered at the Bragg angle expected for the (400) plane of Si(100). The angular width is equivalent to the energy width of 0.5 keV. We found that as the curvature radius of Si becomes small, the integrated reflectivity becomes larger. The modulation factor was measured to be about 0.8 for 8 keV. For the Fe-K lines (similar to 7 keV), which are very important for X-ray astronomy, higher modulation factor close to 1 is expected. The large sensitivity in wide energy band with the high modulation factor indicates that the bent crystal can be a new tool for the X-ray imaging polarimeter. A preliminary design of the polarimetric optics composed by the Si(100) crystal and a small-size imaging detector (e. g. X-ray CCD camera) is proposed in our presentation. Since any kind of crystals can be bent with our method, higher performance will be obtained with changing the crystal.

    DOI: 10.1063/1.3696181

    Web of Science

    researchmap

  • A large X-ray flare from a single weak-lined T Tauri star TWA-7 detected with MAXI GSC 査読

    Akiko Uzawa, Yohko Tsuboi, Mikio Morii, Kyohei Yamazaki, Nobuyuki Kawai, Masaru Matsuoka, Satoshi Nakahira, Motoko Serino, Takanori Matsumura, Tatehiro Mihara, Hiroshi Tomida, Yoshihiro Ueda, Mutsumi Sugizaki, Shiro Ueno, Arata Daikyuji, Ken Ebisawa, Satoshi Eguchi, Kazuo Hiroi, Masaki Ishikawa, Naoki Isobe, Kazuyoshi Kawasaki, Masashi Kimura, Hiroki Kitayama, Mitsuhiro Kohama, Taro Kotani, Yujin E. Nakagawa, Motoki Nakajima, Hitoshi Negoro, Hiroshi Ozawa, Megumi Shidatsu, Tetsuya Sootome, Kousuke Sugimori, Fumitoshi Suwa, Hiroshi Tsunemi, Ryuichi Usui, Takayuki Yamamoto, Kazutaka Yamaoka, Atsumasa Yoshida

    Publications of the Astronomical Society of Japan   63 ( SPEC. ISSUE 3 )   713 - 716   2011年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We present a large X-ray flare from a nearby weak-lined T Tauri star TWA-7 detected with the Gas Slit Camera (GSC) on the Monitor of All-sky X-ray Image (MAXI). The GSC captured X-ray flaring from TWA-7 with a flux of 3 × 10-9 erg cm-2 s-1 in 2-20 keV band during the scan transit starting at 2010-09-07 18:24:30 (UT). The estimated X-ray luminosity at the scan in the energy band is 3 × 1032 erg s-1, indicating that the event is among the largest X-ray flares from T Tauri stars. Since MAXI GSC monitors a target only during a scan transit of about a minute per 92 min orbital cycle, the luminosity at the flare peak might have been higher than that detected. At the scan transit, we observed a high X-ray-to-bolometric luminosity ratio, logLX=Lbol = -0.1+0.2-0.3; i.e., the X-ray luminosity is comparable to the bolometric luminosity. Since TWA-7 has neither an accreting disk nor a binary companion, the observed event implies that none of those are essential to generate such big flares in T Tauri stars. © 2011. Astronomical Society of Japan.

    DOI: 10.1093/pasj/63.sp3.S713

    Scopus

    researchmap

  • The First MAXI/GSC Catalog in the High Galactic-Latitude Sky 査読

    K. Hiroi, 筆頭著者名

    63   S677 - S689   2011年11月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1093/pasj/63.sp3.S677

    Web of Science

    researchmap

  • Peculiarly Narrow SED of GRB 090926B with MAXI and Fermi/GBM 査読

    63   S1035 - S1040   2011年11月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1093/pasj/63.sp3.S1035

    Web of Science

    researchmap

  • Revisit of Local X-Ray Luminosity Function of Active Galactic Nuclei with the MAXI Extragalactic Survey 査読

    Y. Ueda, 頭著者名

    63   S937 - S945   2011年11月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1093/pasj/63.sp3.S937

    Web of Science

    researchmap

  • MAXI GSC Monitoring of the Crab Nebula and Pulsar during the GeV Gamma-Ray Flare in 2010 September 査読

    M. Morii, 頭著者名

    63   S821 - S825   2011年11月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1093/pasj/63.sp3.S821

    Web of Science

    researchmap

  • The variable X-ray spectrum of the Wolf-Rayet binary WR140 with Suzaku 査読

    Y. Sugawara, 著

    2011年1月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    researchmap

  • Suzaku monitoring of the Wolf-Rayet binary WR140 査読

    Yasuharu Sugawara, Yoshitomo Maeda, Yohko Tsuboi, Kenji Hamaguchi

    X-RAY ASTRONOMY-2009: PRESENT STATUS, MULTI-WAVELENGTH APPROACH AND FUTURE PERSPECTIVES, PROCEEDINGS   1248   9 - +   2010年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    We report the preliminary results of the Suzalcu observations of the W-R binary WR 140 (WC7+O5I). We executed the observations at four different epochs around periastron passage in Jan. 2009 to understand the W-R stellar wind as well as the wind-wind collision shocks. The total exposure was 210 ksec. We detected hard X-ray excess in the HXD band (> 10 keV) for the first time from a W-R binary. Another notable discovery was a soft component which is not absorbed even by the dense wind. The spectra can be fitted by three different components; one is for the stationary cool component with kT similar to 0.1 key, one for a dominant high temperature component with kT similar to 3 keV and one for the hardest power-low component with Gamma similar to 2. The column density at periastron is 30 times higher than that at pre-periastron, which can be explained as self-absorption by the W-R wind. The emission measure of the dominant, high temperature component is not inversely proportional to the distance between the two stars.

    Web of Science

    researchmap

  • An X-ray Study of a Massive Star and its Wind 査読

    Yoshitomo Maeda, Yasuharu Sugawara, Yohko Tsuboi, Kenji Hamaguchi

    DECIPHERING THE ANCIENT UNIVERSE WITH GAMMA-RAY BURSTS   1279   363 - +   2010年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    WR 140 is one of the best known examples of a Wolf-Rayet stars. We executed the Suzaku X-ray observations at four different epochs around periastron passage in Jan. 2009 to understand the W-R stellar wind as well as the wind-wind collision shocks. The column density at periastron is about 30 times higher than that at pre-periastron, which can be explained as self-absorption by the Wolf-Rayet wind. The spectra are dominated by a line and continuum emission from a optically thin-thermal plasma. The strong Ne-K lines are evidence that the thermal plasma is shock-heated W-R wind materials by the interaction with the wind from the companion O star. We present the parameters of the wind, such as a mass-loss rate, which were calculated with the absorption and line emission in the spectra.

    Web of Science

    researchmap

  • Suzaku X-Ray Imaging and Spectroscopy of Cassiopeia A 査読

    Yoshitomo Maeda, Yasunobu Uchiyama, Aya Bamba, Hiroko Kosugi, Hiroshi Tsunemi, Eveline A. Helder, Jacco Vink, Natsuki Kodaka, Yukikatsu Terada, Yasushi Fukazawa, Junko Hiraga, John P. Hughes, Motohide Kokubun, Tomomi Kouzu, Hironori Matsumoto, Emi Miyata, Ryoko Nakamura, Shunsaku Okada, Kentaro Someya, Toru Tamagawa, Keisuke Tamura, Kohta Totsuka, Yohko Tsuboi, Yuichiro Ezoe, Stephen S. Holt, Manabu Ishida, Tsuneyoshi Kamae, Robert Petre, Tadayuki Takahashi

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   61 ( 6 )   1217 - 1228   2009年12月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS  

    Suzaku X-ray observations of a young supernova remnant, Cassiopeia A, were carried out. K-shell transition lines from highly ionized ions of various elements were detected, including Chromium (Cr-K alpha at 5.61 keV). The X-ray continuum spectra were modeled in the 3.4-40keV band, summed over the entire remnant, and were fitted with a simplest combination of the thermal bremsstrahlung and the non-thermal cut-off power-law models. The spectral fits with this assumption indicate that the continuum emission is likely to be dominated by non-thermal emission with a cut-off energy at > 1 keV. The thermal-to-non thermal fraction of the continuum flux in the 4-10 keV band is best estimated as similar to 0.1. Non-thermal-dominated continuum images in the 4-14 keV band were made. The peak of the non-thermal X-rays appears at the western part. The peak position of the TeV gamma-rays measured with HEGRA and MAGIC is also shifted at the western part with the I-sigma confidence. Since the location of the X-ray continuum emission was known to be presumably identified with the reverse shock region, the possible keV-TeV correlations give a hint that the accelerated multi-TeV hadrons in Cassiopeia A are dominated by heavy elements in the reverse shock region.

    DOI: 10.1093/pasj/61.6.1217

    Web of Science

    researchmap

  • X-RAYS FROM THE POWER SOURCES OF THE CEPHEUS A STAR-FORMING REGION

    Steven H. Pravdo, Yohko Tsuboi, Akiko Uzawa, Yuichiro Ezoe

    ASTROPHYSICAL JOURNAL   704 ( 2 )   1495 - 1505   2009年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We report an observation of X-ray emission from the exciting region of Cepheus A with the Chandra/ACIS instrument. What had been an unresolved X-ray source comprising the putative power sources is now resolved into at least three point-like sources, each with similar X-ray properties and differing radio and submillimeter properties. The sources are HW9, HW3c, and a new source that is undetected at other wavelengths "h10." They each have inferred X-ray luminosities >= 10(31) erg s(-1) with hard spectra, T >= 10(7) K, and high low-energy absorption equivalent to tens to as much as a hundred magnitudes of visual absorption. The star usually assumed to be the most massive and energetic, HW2, is not detected with an upper limit about seven times lower than the detections. The X-rays may arise via thermal bremsstrahlung in diffuse emission regions associated with a gyrosynchrotron source for the radio emission, or they could arise from powerful stellar winds. We also analyzed the Spitzer/IRAC mid-IR observation from this star formation region and present the X-ray results and mid-IR classifications of the nearby stars. HH 168 is not as underluminous in X-rays as previously reported.

    DOI: 10.1088/0004-637X/704/2/1495

    Web of Science

    Scopus

    researchmap

  • Super-Hard X-Ray Emission from eta Carinae Observed with Suzaku 査読

    Akiko Sekiguchi, Masahiro Tsujimoto, Shunji Kitamoto, Manabu Ishida, Kenji Hamaguchi, Hideyuki Mori, Yohko Tsuboi

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   61 ( 4 )   629 - 637   2009年8月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS  

    We present the Suzaku results of eta Carinae in the 5-50 keV range conducted twice around the apastron in 2005 August for 50 ks and in 2006 February for 20 ks. The X-ray Imaging Spectrometer (XIS) produced hard (5-12 keV) band spectra, resolving K shell lines from highly ionized Fe and Ni. The Hard X-ray Detector yielded a significant detection in the super-hard (15-50 keV) band, which was uncontaminated by near-by sources. We constrained the temperature of the optically thin thermal plasma emission dominant in the hard band to be 3-4 keV using the K-shell line features with the XIS. We found significant excess emission above the thermal emission in the super-hard band with the PIN, confirming the previous INTEGRAL ISGRI report. The entire 5-50 keV spectra were fitted by a combination of a thermal plasma model plus a flat power-law, or a very hot thermal bremsstrahlung model for the excess emission. No significant change of the excess emission was found at different epochs within the systematic and statistical uncertainties, and no flare-like flux amplification was seen in the hard band, indicating that the excess emission is a steady phenomenon. We argue that the super-hard emission is attributable to the inverse Compton of stellar UV photons by non-thermal electrons or to the thermal bremsstrahlung of very hot plasma, and not to the bremsstrahlung by non-thermal electrons colliding with cold ambient matter.

    DOI: 10.1093/pasj/61.4.629

    Web of Science

    researchmap

  • GGD 27: X-RAYS FROM A MASSIVE PROTOSTAR WITH AN OUTFLOW 査読

    Steven H. Pravdo, Yohko Tsuboi, Yuichiro Suzuki, Timothy J. Thompson, Luisa Rebull

    ASTROPHYSICAL JOURNAL   690 ( 1 )   850 - 861   2009年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We report the discovery of a cluster of Class I protostars in GGD 27. One of these protostars is the previously known, centrally located, GGD 27-ILL, which powers a massive bipolar outflow. We show that GGD 27-ILL, which is known to be the bright infrared (IR) source, IRAS 18162-2048, and a compact radio continuum source, is also the newly discovered hard X-ray source, GGD 27-X. The observations were made with the ACIS instrument on the Chandra X-ray Observatory. The X-rays from GGD 27-X are variable when compared with 4 years earlier, with an unabsorbed 2-10 keV X-ray luminosity in this observation of 1.5-12 x 10(31) erg s(-1) and a plasma temperature of >= 10(7) K. The X-rays are probably associated with the underlying B0 star (rather than outflowing material), providing a rare glimpse in hard X-rays of an optically obscured massive protostar with an outflow. The X-ray luminosity and spectrum appear to be consistent with stars of its type in other star formation regions. Several other variable X-ray sources are also detected in the IR cluster that contains GGD 27-X. We also discuss another nearby cluster. In each of the clusters there is an object that is X-ray hard, highly absorbed at low energies, in a blank optical/IR/radio field, and variable in X-ray intensity by a factor of >= 10 on a timescale of 4 years. These latter objects may arise from more recent episodes of star formation or may be "hidden" Class III sources.

    DOI: 10.1088/0004-637X/690/1/850

    Web of Science

    researchmap

  • Redshifted emission lines and radiative recombination continuum from the Wolf-Rayet binary theta Muscae: evidence for a triplet system? 査読

    Y. Sugawara, Y. Tsuboi, Y. Maeda

    ASTRONOMY & ASTROPHYSICS   490 ( 1 )   259 - 264   2008年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:EDP SCIENCES S A  

    We present XMM-Newton observations of the WC binary theta Muscae (WR 48), the second brightest Wolf-Rayet binary in optical wavelengths. The system consists of a short-period (19.1375 days) WC5/WC6 + O6/O7V binary and possibly has an additional O supergiant companion (O9.5/B0Iab) which is optically identified at a separation of similar to 46 mas. Strong emission lines from highly ionized ions of C, O, Ne, Mg, Si, S, Ar, Ca and Fe are detected. The spectra are fitted by a multi-temperature thin-thermal plasma model with an interstellar absorption N(H) = 2-3 x 10(21) cm(-2). Lack of nitrogen line indicates that the abundance of carbon is at least an order of magnitude larger than that of nitrogen. A Doppler shift of similar to 630 km s(-1) is detected for the O VIII line, while similar shifts are obtained from the other lines. The reddening strongly suggests that the emission lines originated from the wind-wind shock zone, where the average velocity is similar to 600 km s(-1). The red-shift motion is inconsistent with a scenario in which the X-rays originate from the wind-wind collision zone in the short-period binary, and would be evidence supporting the widely separated O supergiant as a companion. This may make up the collision zone be lying behind the short-period binary. In addition to the emission lines, we also detected the RRC (radiative recombination continuum) structure from carbon around 0.49 keV. This implies the existence of additional cooler plasma.

    DOI: 10.1051/0004-6361:20079302

    Web of Science

    researchmap

  • Suzaku detection of an intense X-ray flare from an A-type star, HD 161084 査読

    Miura Junichiro, Tsujimoto Masahiro, Tsuboi Yohko, Maeda Yoshitomo, Sugawara Yasuharu, Koyama Katsuji, Yamauchi Shigeo

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   60   S49 - S56   2008年2月

  • Suzaku Observations of the North Polar Spur: Evidence for Nitrogen Enhancement 査読

    E. D. Mille, 頭著者

    2008年2月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    researchmap

  • Measuring the Broad-Band X-Ray Spectrum from 400eV to 40keV in the Southwest Part of the Supernova Remnant RXJ1713.7-3946 査読

    T. Takahashi, 頭著者名

    60 ( SPEC. ISS. 1 )   2008年2月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1093/pasj/60.sp1.s131

    Scopus

    researchmap

  • Suzaku spectroscopy of extended X-ray emission in M 17 査読

    Yoshiaki Hyodo, Masahiro Tsujimoto, Kenji Hamaguchi, Katsuji Koyama, Shunji Kitamoto, Yoshitomo Maeda, Yohko Tsuboi, Yuichiro Ezoe

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   60   S85 - S93   2008年2月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS  

    We present the results of a Suzaku spectroscopic study of soft extended X-ray emission in the H II region of M 17. The spectrum of the extended emission was obtained with a high signal-to-noise ratio in a spatially resolved manner using the X-ray Imaging Spectrometer (XIS). We established that contamination by unresolved point sources, the Galactic Ridge X-ray emission, the cosmic X-ray background, and the local hot bubble emission is negligible in the background-subtracted XIS spectrum of the diffuse emission. Half a dozen emission lines were clearly resolved for the first time, including K alpha lines of highly ionized O, Ne, and Mg as well as L-series complex of Fe at 0.5-1.5keV. Based on diagnosis of these lines, we obtained the following results: (1) the extended emission is an optically thin thermal plasma, represented well by a single temperature of similar to 3.0 +/- 0.4 MK, (2) the abundances of elements with emission lines in the diffuse spectrum are 0.1-0.3 solar, while those of bright discrete sources are 0.3-1.5 solar, (3) the metal abundances relative to each other in the diffuse emission are consistent with solar, except for a Ne enhancement of a factor of similar to 2, (4) both the plasma temperature and the chemical composition of the diffuse emission show no spatial variation across the studied spatial scale of similar to 5 pc.

    DOI: 10.1093/pasj/60.sp1.S85

    Web of Science

    researchmap

  • Oxygen line mapping of SN 1006 with Suzaku 査読

    A.Bamba|rn, 筆頭著者

    41 ( 3 )   411 - 415   2008年

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1016/j.asr.2007.03.055

    Scopus

    researchmap

  • X-Ray Imaging Spectrometer (XIS) on Board Suzaku 査読

    K. Koyama, 頭著者

    PASJ : publications of the Astronomical Society of Japan   59 ( 1 )   S23 - S33   2007年1月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    CiNii Books

    researchmap

  • The X-Ray Observatory Suzaku 査読

    K. Mitsuda, 頭著者名

    4   2526 - 2531   2007年1月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1109/NSSMIC.2007.4436667

    Scopus

    researchmap

  • Discovery of a new X-ray transient source in the Scutum region with Suzaku 査読

    Shigeo Yamauchi, Ken Ebisawa, Aya Bamba, Manabu Ishida, Kazushi Iwasawa, Yasuo Tanaka, Motohide Kokubun, Katsuji Koyama, Hiromitsu Takahashi, Yohko Tsuboi

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   59   S215 - S220   2007年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS  

    During an observation of the Galactic plane in the Scutum region with the Suzaku satellite, we discovered a new X-ray transient source, designated Suzaku J1844-0404. Compared with previous Chandra observations of the same field, four Chandra X-ray sources exist within the current positional uncertainty of Suzaku J1844-0404. A firm identification is not possible. From the beginning of the observation, the X-ray intensity was significant at similar to 5 x 10(-14) erg s(-1) cm(-2) (2-10 keV), which may be a possible precursor. Later, the source exhibited a flare with a peak flux of similar to 10(-12) erg s(-1) cm(-2) (2-10 keV). A strong and narrow emission line at similar to 6.66 keV was observed during the flare, most likely the He-like Fe line. The spectrum in 1-10 keV is consistent with a heavily absorbed (N-H similar to 3 x 10(22) H cm(-2)) thin thermal emission with kT as high as similar to 7 keV. A single short flare, as observed, is rather unlikely for a cataclysmic variable. The source is probably an active binary star or a young stellar object.

    DOI: 10.1093/pasj/59.sp1.S215

    Web of Science

    researchmap

  • Suzaku observations of the local and distant hot ISM 査読

    Randall K. Smith, Mark W. Bautz, Richard J. Edgar, Ryuichi Fujimoto, Kenji Hamaguchi, John R. Hughes, Manabu Ishida, Richard Kelley, Caroline A. Kilbourne, K. D. Kuntz, Dan McCammon, Eric Miller, Kazuhisa Mitsuda, Koji Mukai, Paul P. Plucinsky, F. Scott Porter, Steve L. Snowden, Yoh Takei, Yukikatsu Terada, Yohko Tsuboi, Noriko Y. Yamasaki

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   59   S141 - S150   2007年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS  

    Suzaku observed the molecular cloud MBM 12 and a blank field less than 3 degrees away to separate the local and distant components of the diffuse soft X-ray background. Towards MBM 12, a local (D less than or similar to 275 pc) O VII emission line was clearly detected with an intensity of 3.5 photons cm(-2) s(-1) sr(-1) (or line units, LU), and the O VIII flux was < 0.34 LU. The origin of this O VII emission could be hot gas in the Local Hot Bubble (LHB), charge exchange within the heliosphere with oxygen ions from the solar wind (SWCX), or both. If entirely from the LHB, the emission could be explained by a region with emission measure of 0.0075 cm(-6) pc and a temperature of 1.2 x 10(6) K. However, this temperature and emission measure implies 1/4 keV emission in excess of observations. There is no evidence in the X-ray light curve or solar wind data for a significant contribution from geocoronal SWCX, although interplanetary SWCX is still possible. In any case, the observed O VII flux represents an upper limit to both the LHB emission and interplanetary SWCX in this direction. The blank field was observed immediately afterwards. The net off-cloud O VII and O VIII intensities were (respectively) 2.34 +/- 0.33 and 0.77 +/- 0.16 LU, after subtracting the on-cloud foreground emission. If this more distant O VII and O VIII emission is from a thermal plasma in collisional equilibrium beyond the Galactic disk, we infer it has a temperature of (2.1 +/- 0.1) x 10(6) K with an emission measure of (4 +/- 0.6) x 10(-3) cm(-6) pc.

    DOI: 10.1093/pasj/59.sp1.S141

    Web of Science

    researchmap

  • Suzaku observation of diffuse X-ray emission from the Carina Nebula 査読

    Kenji Hamaguchi, Robert Petre, Hironori Matsumoto, Masahiro Tsujimoto, Stephen S. Holt, Yuichiro Ezoe, Hideki Ozawa, Yohko Tsuboi, Yang Soong, Shunji Kitamoto, Akiko Sekiguchi, Motohide Kokubun

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   59 ( SP1 )   S151 - S161   2007年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS  

    We studied extended X-ray emission from the Carina Nebula taken with the Suzaku CCD camera XIS on 2005 August 29. The X-ray morphology, plasma temperature, and absorption to the plasma are consistent with the earlier Einstein results. The Suzaku spectra newly revealed emission lines from various species, including oxygen, but not from nitrogen. This result restricts the N/O ratio to be significantly low, compared with evolved massive stellar winds, suggesting that the diffuse emission originated in an old supernova remnant or a super shell produced by multiple supernova remnants. The X-ray spectra from the north and south of eta Car showed distinct differences between 0.3-2 keV. The south spectrum shows strong L-shell lines of iron ions and K-shell lines of silicon ions, while the north spectrum shows them weak in intensity. This means that the silicon and iron abundances are a factor of 2-4 higher in the south region than in the north region. The abundance variation may be produced by an SNR ejecta, or related to dust formation around the star-forming core.

    DOI: 10.1093/pasj/59.sp1.S151

    Web of Science

    researchmap

  • Iron and nickel line diagnostics for the Galactic Center diffuse emission 査読

    Katsuji Koyama, Yoshiaki Hyodo, Tatsuya Inui, Hiroshi Nakajima, Hironori Matsumoto, Takeshi Go Tsuru, Tadayuki Takahashi, Yoshitomo Maeda, Noriko Y. Yamazaki, Hiroshi Murakami, Shigeo Yamauchi, Yohko Tsuboi, Atsushi Senda, Jun Kataoka, Hiromitsu Takahashi, Stephen S. Holt, Gregory V. Brown

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   59 ( SP1 )   S245 - S255   2007年1月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS  

    We have observed the diffuse X-ray emission from the Galactic Center (GC) using the X-ray Imaging Spectrometer (XIS) on Suzaku. The high-energy resolution and the low-background orbit provided excellent spectra of the GC diffuse X-rays (GCDX). The XIS found many emission lines in the GCDX near the energy of K-shell transitions of iron and nickel. The most pronounced features are Fe I K alpha at 6.4 keV and K-shell absorption edge at 7.1 keV, which are from neutral and/or low ionization states of iron, and the K-shell lines at 6.7 keV and 6.9 keV from He-like (Fe XXV K alpha) and hydrogenic (Fe XXVI Ly alpha) ions of iron. In addition, K alpha lines from neutral or low ionization nickel (Ni I K alpha) and He-like nickel (Ni XXVII K alpha), Fe I K beta, Fe XXV K beta, Fe XXVI Ly beta, Fe XXV K gamma, and Fe XXVI Ly gamma were detected for the first time. The line center energies and widths of Fe XXV K alpha and Fe XXVI Ly alpha favor a collisional excitation plasma for the origin of the GCDX. The electron temperature determined from the line flux ratio of Fe XXV K alpha/Fe XXV K beta is similar to the ionization temperature determined from that of Fe XXV K alpha/Fe XXVI Ly alpha. Thus it would appear that the GCDX plasma is close to ionization equilibrium. The 6.7 keV flux and temperature distribution to the galactic longitude is smooth and monotonic, in contrast to the integrated point source flux distribution. These facts support the hypothesis that the GCDX is truly diffuse emission rather than the integration of the outputs of a large number of unresolved point sources. In addition, our results demonstrate that the chemical composition of Fe in the interstellar gas near the GC is constrained to be about 3.5 times solar abundance.

    DOI: 10.1093/pasj/59.sp1.S245

    Web of Science

    researchmap

  • Millenium study of SN 1006 with Suzaku

    Aya Bamba, Hiroya Yamaguchi, Katsuji Koyama, Junko S. Hiraga, Steve Holt, John P. Hughes, Hideaki Katagiri, Jun Kataoka, Shunji Kitamoto, Motohide Kokubun, Hironori Matumoto, Emi Miyata, Koji Mori, Hiroshi Nakajima, Masanobu Ozaki, Robert Petre, Akiko Sekiguchi, Tadayuki Takahashi, Takaaki Tanaka, Yukikatsu Terada, Hiroshi Tomida, Hiroshi Tsunemi, Yohko Tsuboi, Masahiro Tsujimoto, Yasunobu Uchiyama, Masaru Ueno, Shin Watanabe

    Progress of Theoretical Physics Supplement   ( 169 )   142 - 145   2007年

     詳細を見る

    掲載種別:研究論文(国際会議プロシーディングス)  

    SN 1006 is the milestone of understanding the acceleration mechanism of cosmic rays, and this year is the millennium year for the remnant. We carried out SN 1006 mapping observations with the X-ray Imaging Spectrometers (XIS) onboard Suzaku satellite. Thanks to the excellent spectral response of XIS, K emission lines from highly ionized oxygen were clearly resolved. The intensity maps of these lines have been made additional to the intensity and photon index maps of the nonthermal component. We discovered that regions with strong and hard nonthermal component has weak thermal emission. The north rim of the SNR has the hardest nonthermal component. These facts might have information of efficient cosmic ray acceleration and background plasma.

    DOI: 10.1143/PTPS.169.142

    Scopus

    researchmap

  • X-ray and near-infrared studies of the star-forming cloud L1448 査読

    M Tsujimoto, N Kobayashi, Y Tsuboi

    ASTRONOMICAL JOURNAL   130 ( 5 )   2212 - 2219   2005年11月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:UNIV CHICAGO PRESS  

    We present the results of X-ray and near-infrared (NIR) observations of L1448, a star-forming region in the Perseus cloud complex using the Chandra X-Ray Observatory and the 4 m telescope at the Kitt Peak National Observatory. We detect 72 X-ray sources in a similar to 17' x 17' region with a similar to 68 ks ACIS exposure down to the X-ray flux limit of similar to 10(-15) ergs s(-1) cm(-2) (0.5 - 8 keV), for which we conduct follow-up NIR imaging observations in a concentric similar to 11' x 11' region with FLAMINGOS down to m(KS) similar to 17 mag. Twelve X-ray sources have NIR or optical counterparts. By plotting X-ray mean energy versus the NIR-to-X-ray flux ratio, the X-ray sources are clearly separated into two groups. The X-ray spectral and temporal features, as well as NIR magnitudes and colors, indicate that one group mainly consists of young stellar objects (YSOs) in the cloud and the other of background extragalactic sources. Ten X-ray-emitting YSO candidates are thus newly identified as low-mass or brown dwarf mass sources from their NIR magnitudes. In addition, a possible X-ray signal is found from a midinfrared protostar, L1448 IRS 3( A). The lack of detection of this source in our deep NIR images indicates that this source has a very steep spectral slope of greater than or similar to 3.2 in the 2 - 10 mu m wavelength range.

    Web of Science

    researchmap

  • Iron fluorescent line emission from young stellar objects in the Orion Nebula 査読

    M Tsujimoto, ED Feigelson, N Grosso, G Micela, Y Tsuboi, F Favata, H Shang

    ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES   160 ( 2 )   503 - 510   2005年10月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:UNIV CHICAGO PRESS  

    We present the result of a systematic search for the iron K alpha fluorescent line at similar to 6.4 keV among 1616 X-ray sources detected by ultradeep Chandra observations of the Orion Nebula Cluster and the obscured Orion Molecular Cloud 1 population as part of the Chandra Orion Ultradeep Project ( COUP). Seven sources are identified to have an excess emission at similar to 6.4 keV among 127 control sample sources with significant counts in the 6.0 - 9.0 keV band. These seven sources are young stellar objects (YSOs) characterized by intense flarelike flux variations, thermal spectra, and near-infrared (NIR) counterparts. The observed equivalent widths of the line cannot be attributed to the florescence by interstellar or circumstellar matter along the line of sight. The X-ray spectral fits and NIR colors of the 6.4 keV sources show that these sources have X-ray absorption of greater than or similar to 1 x 10(22) cm(-2) and NIR excess emission, which is not expected when the fluorescence occurs at the stellar photosphere. We therefore conclude that the iron fluorescent line of YSOs arises from reflection off of circumstellar disks, which are irradiated by the hard X-ray continuum emission of magnetic reconnection flares.

    Web of Science

    researchmap

  • A Search for X-Rays from the Long-Duration Microlensing Event MACHO-96-BLG-5 査読

    Y. Maeda

    2005年9月

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    researchmap

  • X-rays from Cepheus A East and West 査読

    SH Pravdo, Y Tsuboi

    ASTROPHYSICAL JOURNAL   626 ( 1 )   272 - 282   2005年6月

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:UNIV CHICAGO PRESS  

    We report the discovery of X-rays from both components of Cepheus A, East and West, with the XMM-Newton observatory. HH 168 joins the ranks of other energetic Herbig-Haro objects that are sources of T ≥ 10(6) K X-ray emission. The effective temperature of HH 168 is T = 5.8(-2.3)(+3.5) x 10(6) K, and its unabsorbed luminosity is 1: 1; 10(29) ergs s(-1), making it hotter and less luminous than other representatives of its class. We also detect prominent X-ray emission from the complex of compact radio sources believed to be the power sources for Cep A. We call this source HWX, and it is distinguished by its hard X-ray spectrum, T = 1.2(-0.5)(+1.2) 10(8) K, and its complex spatial distribution. It may arise from one or more protostars associated with the radio complex, the outflows, or a combination of the two. We detect 102 X-ray sources, many presumed to be pre-main-sequence stars on the basis of the reddening of their optical and IR counterparts.

    Web of Science

    researchmap

  • XMM-Newton observations of the Mouse, SLX 1744 299 and SLX 1744 300 査読

    H. Mori, 筆頭著者名含

    2005年

     詳細を見る

    記述言語:日本語   掲載種別:研究論文(学術雑誌)  

    researchmap

  • Chandra Orion Ultra-deep Project: A search for 6.4 keV iron fluorescent line from young stellar objects 査読

    M Tsujimoto, ED Feigelson, N Grosso, G Micela, Y Tsuboi, F Favata

    Proceedings of the 13th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun - Proceedings, Vols 1 and 2   560   1005 - 1008   2005年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:EUROPEAN SPACE AGENCY  

    We present the result of a coherent search for the iron K. fluorescent line at similar to 6.4 keV among 1616 X-ray sources detected by ultradeep Chandra observations of the Orion Nebula Cluster (ONC) -Chandra Orion Ultra-deep Project (COUP). Seven sources are identified to have an excess emission at similar to 6.4 keV among 127 control sample sources with significant counts in the 6.0-9.0 keV band. These seven sources axe considered to be young stellar objects (YSOs) belonging to ONC from their flare-like flux variation, thermal spectra, and near-infrared (NIR) or centimeter identifications. We discuss that the observed equivalent widths of the fluorescent line can not be accounted with the reflection by interstellar or circumstellar matter in the line of sight. The X-ray spectral fittings and NIR colors of the 6.4 keV sources show that these sources preferentially have X-ray absorption of > 1x10(22) cm(-2) and NIR excess emission, which are not expected when the reflection occurs at the stellar photosphere. We therefore conclude that the iron fluorescent line of YSOs arises at disks, which are photoionized by the strong continuum emission from X-ray flares.

    Web of Science

    researchmap

  • Magnetic activities on young stars 査読

    K Hamaguchi, Y Tsuboi, K Imanishi, K Koyama

    EARTH PLANETS AND SPACE   53 ( 6 )   683 - 687   2001年

     詳細を見る

    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:TERRA SCIENTIFIC PUBL CO  

    Almost all young stellar objects (YSOs) are now known to emit X-rays driven by the magnetic activity. The solar-type dynamo is the plausible mechanism to generate the magnetic fields, but it does not work properly on protostars or intermediate-mass YSOs due to the difference of their stellar inner structure. To find an alternative mechanism, the structure and energy of magnetic fields surrounding stars should be investigated. In this sence, a stellar X-ray flare gives us important information because it directly traces an activity of one magnetic loop. With this motivation, we searched for stellar X-ray flares using the ASCA satellite and detected seven flares from low-mass and intermediate-mass YSOs. By comparing flare parameters with the absorption column density (NH), we found that younger stars tend to have higher plasma temperature and larger emitting volumes. Furthermore, the flare loop size should be far larger than the solar radii in low-mass protostars and Herbig Ae/Be stars (HAEBEs). These facts suggest that the magnetic fields of low-mass protostars and HAEBEs far extend from the stellar main body and probably connect to the circumstellar disks, and that the magnetic reconnection by the star-disk differential rotation should energize the X-ray flares. We also present supporting evidence of quasi-periodic flares detected on the ClassI protostar YLW15.

    Web of Science

    researchmap

▼全件表示

書籍等出版物

  • X線で探る星の爆発現象

    ( 担当: 単著)

    2010年12月 

     詳細を見る

    記述言語:日本語  

    researchmap

MISC

  • The peculiar X-ray variations of the enigmatic massive binary WR 21a

    Sugawara, Yasuharu, Tsuboi, Yohko, Maeda, Yoshitomo

    Suzaku-MAXI 2014: Expanding the Frontiers of the X-ray Universe   pp.pp220-221   2014年9月

     詳細を見る

  • An X-ray spectral study of colliding wind binaries

    Yasuharu Sugawara, Yoshitomo Maeda, Yohko Tsuboi

    SUZAKU 2011: EXPLORING THE X-RAY UNIVERSE: SUZAKU AND BEYOND   1427   296 - 297   2012年

     詳細を見る

    記述言語:英語   出版者・発行元:AMER INST PHYSICS  

    We present results of spectral studies of two Wolf-Rayet colliding wind binaries (WR 140 and WR 30a), using the data obtained by the Suzaku and XMM-Newton satellites. WR 140 is one of the best known examples of a Wolf-Rayet star. We executed the Suzaku X-ray observations at four different epochs around periastron passage in Jan. 2009 to understand the W-R stellar wind as well as the wind-wind collision shocks. We detected hard X-ray excess in the HXD band (> 10 key) for the first time from a W-R binary. The luminosity of the dominant, high temperature component is not inversely proportional to the distance between the two stars. WR 30a is the rare WO-type W-R binary. We executed XMM-Newton observations and detected X-ray emission for the first time. The broad-band spectrum was well-fitted with double-absorption model. The hard X-ray emission was heavily absorbed. This can be interpreted that the hard X-ray emitting plasma exist near WO star.

    DOI: 10.1063/1.3696211

    Web of Science

    Scopus

    researchmap

  • The young stellar population in M17 revealed by Chandra

    Patrick S. Broos, Eric D. Feigelson, Leisa K. Townsley, Konstantin V. Getman, Junfeng Wang, Gordon P. Garmire, Zhibo Jiang, Yohko Tsuboi

    ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES   169 ( 2 )   353 - 385   2007年4月

     詳細を見る

    記述言語:英語   掲載種別:書評論文,書評,文献紹介等   出版者・発行元:IOP PUBLISHING LTD  

    We report here results from a Chandra ACIS observation of the stellar populations in and around the M17 H II region. The field reveals 886 sources with observed X-ray luminosities (uncorrected for absorption) between similar to 29.3 ergs s(-1) < log L(X) < 32.8 ergs s(-1), 771 of which have stellar counterparts in infrared images. In addition to comprehensive tables of X-ray source properties, several results are presented:
    1. The X-ray luminosity function is calibrated to that of the Orion Nebula Cluster population to infer a total population of roughly 8000-10,000 stars in M17, one-third lying in the central NGC 6618 cluster.
    2. About 40% of the ACIS sources are heavily obscured with A(V) > 10 mag. Some are concentrated around well-studied star-forming regions - IRS 5/UC1, the Kleinmann-Wright Object, and M17-North - but most are distributed across the field. As previously shown, star formation appears to be widely distributed in the molecular clouds. X-ray emission is detected from 64 of the hundreds of Class I protostar candidates that can be identified by near- and mid-infrared colors. These constitute the most likely protostar candidates known in M17.
    3. The spatial distribution of X-ray stars is complex: in addition to the central NGC 6618 cluster and well-known embedded groups, we find a new embedded cluster (designated M17-X), a 2 pc long arc of young stars along the southwest edge of the M17 H II region, and 0.1 pc substructure within various populations. These structures may indicate that the populations are dynamically young.
    4. All (14/14) of the known O stars but only about half (19/34) of the known B0-B3 stars in the M17 field are detected. These stars exhibit the long-reported correlation between X-ray and bolometric luminosities of L(X) similar to 10(-7) L(bol). While many O and early-B stars show the soft X-ray emission expected from microshocks in their winds or moderately hard emission that could be caused by magnetically channeled wind shocks, six of these stars exhibit very hard thermal plasma components (kT > 4 keV) that may be due to colliding wind binaries. More than 100 candidate new OB stars are found, including 28 X-ray detected intermediate- and high-mass protostar candidates with infrared excesses.
    5. Only a small fraction (perhaps 10%) of X-ray selected high- and intermediate- mass stars exhibit K-band-emitting protoplanetary disks, providing further evidence that inner disks evolve very rapidly around more massive stars.

    Web of Science

    researchmap

  • Discovery of a possible X-ray counterpart to HESS J1804-216

    Aya Bamba, Katsuji Koyama, Junko S. Hiraga, John P. Hughes, Takayoshi Kohmura, Motohide Kokubun, Yoshitomo Maeda, Hironori Matsumoto, Atsushi Senda, Tadayuki Takahashi, Yohko Tsuboi, Shigeo Yamauchi, Takayuki Yuasa

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   59   S209 - S214   2007年1月

     詳細を見る

    記述言語:英語   掲載種別:機関テクニカルレポート,技術報告書,プレプリント等   出版者・発行元:OXFORD UNIV PRESS  

    Suzaku deep observations have discovered two highly significant nonthermal X-ray sources, Suzaku J1804-2142 (Src 1) and Suzaku J1804-2140 (Src 2), positionally coincident with the unidentified TeV gamma-ray source, HESS J1804-216. The X-ray sources are not time variable and show no Counterpart in other wavebands, except for the TeV source. Src 1 is unresolved at Suzaku spatial resolution, whereas Src 2 is extended or composed of multiple sources. The X-ray spectra are highly absorbed, hard, and featureless, and are well fitted by absorbed power-law models with best-fit photon indices and absorption columns of -0.3(-0.5)(+0.5) and 0.2(-0.2)(+2.0) x 10(22) cm(-2) for Src 1, and 1.7(-1.0)(+1.4) and 1.1(-0.6)(+1.0) x 10(23) cm(-2) for Src 2. The measured X-ray absorption to the latter source is signif icantly larger than the total Galactic neutral hydrogen column in that direction. The unabsorbed 2-10 keV band luminosities are 7.5 x 10(32) (d/5 kpc)(2) erg s(-1) (Src 1) and 1.3 x 10(33) (d/5 kpc)(2) erg s(-1) (Src 2), where d is the source distance. Among the handful of TeV sources with known X-ray counterparts, HESS J1804-216 has the largest ratio of TeV gamma-ray to hard X-ray fluxes. We discuss the nature of the emission and propose the Suzaku sources as plausible counterparts to the TeV source, although further observations are necessary to confirm this.

    DOI: 10.1093/pasj/59.sp1.S209

    Web of Science

    arXiv

    researchmap

  • A high-resolution very large array observation of a protostar in OMC-3: Shock-induced X-ray emission by a protostellar jet

    M Tsujimoto, K Koyama, N Kobayashi, M Saito, Y Tsuboi, CJ Chandler

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   56 ( 2 )   341 - 345   2004年4月

     詳細を見る

    記述言語:英語   出版者・発行元:OXFORD UNIV PRESS  

    Using the Very Large Array (VLA) in the A-configuration, we obtained a high-resolution 3.6 cm map of a hard X-ray source detected by the Chandra X-ray Observatory in a protostellar clump in Orion molecular cloud 3. Two radio continuum sources were detected in the vicinity of the X-ray source, both of which have NIR counterparts. We conclude that these VLA sources are free-free emission produced by shocks in protostellar jets from the NIR class I protostars. Using the centimeter data, we determined the power and orientation of the protostellar jets. The center position of the X-ray emission was found to be similar to 1"-2" offset from the exciting sources of the jets, and the displacement is in the direction of the jets and molecular outflows. We discuss the nature of the X-ray emission as the shock-excited plasma at the shock front where the jet propagates through the interstellar medium at a speed of similar to 1000 km s(-1).

    DOI: 10.1093/pasj/56.2.341

    Web of Science

    researchmap

  • X-rays from HH 80, HH 81, and the central region

    SH Pravdo, Y Tsuboi, Y Maeda

    ASTROPHYSICAL JOURNAL   605 ( 1 )   259 - 271   2004年4月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    We report detections of X-rays from HH 80 and HH 81 with the ACIS instrument on the Chandra X-Ray Observatory. These are among the most luminous Herbig-Haro ( HH) sources in the optical, and they are now the most luminous known in X-rays. These X-rays arise from the strong shocks that occur when the southern extension of this bipolar outflow slams into the ambient material. There is a one-to-one correspondence between regions of high X-ray emission and high Halpha emission. The X-ray luminosities of HH 80 and HH 81 are 4.5 and 4.3 x 10(31) ergs s(-1), respectively, assuming that the measured low-energy absorption is not in the sources. The measured temperature of the HH plasma is not as large as that expected from the maximum velocities seen in the extended tails of the optical emission lines. Rather, it is consistent with the similar to 10(6) K temperature of the "narrow'' core of the optical lines. There is no observed emission from HH 80 North, the northern extension of the bipolar flow, based on a measurement of lower sensitivity. We imaged the central region of the bipolar flow revealing a complex of X-ray sources, including one near but not coincident with the putative power source in the radio and infrared. This source, CXOPTM J181912.4 - 204733, has no counterparts at other wavelengths and is consistent in luminosity and spectrum with a massive star with A(V) similar to 90 mag. It may contribute significantly to the power input to the complex. Alternatively, this emission might be extended X-rays from outflows close to the power source. We detect 94 X-ray sources overall in this area of star formation.

    DOI: 10.1086/382220

    Web of Science

    researchmap

  • X-rays from HH 80, HH 81, and the central region

    SH Pravdo, Y Tsuboi, Y Maeda

    ASTROPHYSICAL JOURNAL   605 ( 1 )   259 - 271   2004年4月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    We report detections of X-rays from HH 80 and HH 81 with the ACIS instrument on the Chandra X-Ray Observatory. These are among the most luminous Herbig-Haro ( HH) sources in the optical, and they are now the most luminous known in X-rays. These X-rays arise from the strong shocks that occur when the southern extension of this bipolar outflow slams into the ambient material. There is a one-to-one correspondence between regions of high X-ray emission and high Halpha emission. The X-ray luminosities of HH 80 and HH 81 are 4.5 and 4.3 x 10(31) ergs s(-1), respectively, assuming that the measured low-energy absorption is not in the sources. The measured temperature of the HH plasma is not as large as that expected from the maximum velocities seen in the extended tails of the optical emission lines. Rather, it is consistent with the similar to 10(6) K temperature of the "narrow'' core of the optical lines. There is no observed emission from HH 80 North, the northern extension of the bipolar flow, based on a measurement of lower sensitivity. We imaged the central region of the bipolar flow revealing a complex of X-ray sources, including one near but not coincident with the putative power source in the radio and infrared. This source, CXOPTM J181912.4 - 204733, has no counterparts at other wavelengths and is consistent in luminosity and spectrum with a massive star with A(V) similar to 90 mag. It may contribute significantly to the power input to the complex. Alternatively, this emission might be extended X-rays from outflows close to the power source. We detect 94 X-ray sources overall in this area of star formation.

    DOI: 10.1086/382220

    Web of Science

    researchmap

  • A high-resolution very large array observation of a protostar in OMC-3: Shock-induced X-ray emission by a protostellar jet

    M Tsujimoto, K Koyama, N Kobayashi, M Saito, Y Tsuboi, CJ Chandler

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   56 ( 2 )   341 - 345   2004年4月

     詳細を見る

    記述言語:英語   出版者・発行元:OXFORD UNIV PRESS  

    Using the Very Large Array (VLA) in the A-configuration, we obtained a high-resolution 3.6 cm map of a hard X-ray source detected by the Chandra X-ray Observatory in a protostellar clump in Orion molecular cloud 3. Two radio continuum sources were detected in the vicinity of the X-ray source, both of which have NIR counterparts. We conclude that these VLA sources are free-free emission produced by shocks in protostellar jets from the NIR class I protostars. Using the centimeter data, we determined the power and orientation of the protostellar jets. The center position of the X-ray emission was found to be similar to 1"-2" offset from the exciting sources of the jets, and the displacement is in the direction of the jets and molecular outflows. We discuss the nature of the X-ray emission as the shock-excited plasma at the shock front where the jet propagates through the interstellar medium at a speed of similar to 1000 km s(-1).

    DOI: 10.1093/pasj/56.2.341

    Web of Science

    researchmap

  • A systematic study of X-ray flares from low-mass young stellar objects in the rho Ophiuchi star-forming region with Chandra

    K Imanishi, H Nakajima, M Tsujimoto, K Koyama, Y Tsuboi

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   55 ( 3 )   653 - 681   2003年6月

     詳細を見る

    記述言語:英語   出版者・発行元:OXFORD UNIV PRESS  

    We report on the results of a systematic study of X-ray flares from low-mass young stellar objects, using two deep exposure Chandra observations of the main region of the rho Ophiuchi star-forming cloud. From 195 X-ray sources, including class I-III sources and some young brown dwarfs, we detected a total of 71 X-ray flares. Most of the flares have the typical profile of solar and stellar flares, fast rise and slow decay, while some bright flares show unusually long rise timescales. We derived the time-averaged temperature (<kT>), luminosity (<L-X>), rise and decay timescales (tau(r) and tau(d)) of the flares, finding that (1) class I-II sources tend to have a high <kT>, which sometimes exceeds 5 keV, (2) the distribution of <L-X> during flares is nearly the same for all classes from similar to 10(29.5) to similar to 10(31.5) ergs(-1), although there is a marginal hint of a higher <L-X> distribution for class I than class II-III, and (3) positive and negative log-linear correlations are found between tau(r), and tau(d), and <kT> and tau(r). In order to explain these relations, we used the framework of magnetic reconnection model with heat conduction and chromospheric evaporation to formulate the observational parameters (tau(r), tau(d), and <kT>) as a function of the pre-flare (coronal) electronic density (n(c)), the half-length of the reconnected magnetic loop (L), and magnetic field strength (B). The observed correlations are well reproduced if loop lengths are nearly the same for all classes, regardless of the existence of an accretion disk. The estimated loop length is almost comparable to the typical stellar radius of these objects (10(10)-10(11) cm), which indicates that the observed flares are triggered by solar-type loops, rather than larger ones (similar to 10(12) cm) connecting the star with its inner accretion disk. The higher <kT> observed for class I sources may be explained by a slightly higher magnetic field strength (approximate to 500G) than for class II-III sources (200-300 G).

    DOI: 10.1093/pasj/55.3.653

    Web of Science

    researchmap

  • A systematic study of X-ray flares from low-mass young stellar objects in the rho Ophiuchi star-forming region with Chandra

    K Imanishi, H Nakajima, M Tsujimoto, K Koyama, Y Tsuboi

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   55 ( 3 )   653 - 681   2003年6月

     詳細を見る

    記述言語:英語   出版者・発行元:OXFORD UNIV PRESS  

    We report on the results of a systematic study of X-ray flares from low-mass young stellar objects, using two deep exposure Chandra observations of the main region of the rho Ophiuchi star-forming cloud. From 195 X-ray sources, including class I-III sources and some young brown dwarfs, we detected a total of 71 X-ray flares. Most of the flares have the typical profile of solar and stellar flares, fast rise and slow decay, while some bright flares show unusually long rise timescales. We derived the time-averaged temperature (<kT>), luminosity (<L-X>), rise and decay timescales (tau(r) and tau(d)) of the flares, finding that (1) class I-II sources tend to have a high <kT>, which sometimes exceeds 5 keV, (2) the distribution of <L-X> during flares is nearly the same for all classes from similar to 10(29.5) to similar to 10(31.5) ergs(-1), although there is a marginal hint of a higher <L-X> distribution for class I than class II-III, and (3) positive and negative log-linear correlations are found between tau(r), and tau(d), and <kT> and tau(r). In order to explain these relations, we used the framework of magnetic reconnection model with heat conduction and chromospheric evaporation to formulate the observational parameters (tau(r), tau(d), and <kT>) as a function of the pre-flare (coronal) electronic density (n(c)), the half-length of the reconnected magnetic loop (L), and magnetic field strength (B). The observed correlations are well reproduced if loop lengths are nearly the same for all classes, regardless of the existence of an accretion disk. The estimated loop length is almost comparable to the typical stellar radius of these objects (10(10)-10(11) cm), which indicates that the observed flares are triggered by solar-type loops, rather than larger ones (similar to 10(12) cm) connecting the star with its inner accretion disk. The higher <kT> observed for class I sources may be explained by a slightly higher magnetic field strength (approximate to 500G) than for class II-III sources (200-300 G).

    DOI: 10.1093/pasj/55.3.653

    Web of Science

    researchmap

  • A systematic study of X-ray flares from low-mass young stellar objects in the rho Ophiuchi star-forming region with Chandra

    K Imanishi, H Nakajima, M Tsujimoto, K Koyama, Y Tsuboi

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   55 ( 3 )   653 - 681   2003年6月

     詳細を見る

    記述言語:英語   出版者・発行元:OXFORD UNIV PRESS  

    We report on the results of a systematic study of X-ray flares from low-mass young stellar objects, using two deep exposure Chandra observations of the main region of the rho Ophiuchi star-forming cloud. From 195 X-ray sources, including class I-III sources and some young brown dwarfs, we detected a total of 71 X-ray flares. Most of the flares have the typical profile of solar and stellar flares, fast rise and slow decay, while some bright flares show unusually long rise timescales. We derived the time-averaged temperature (<kT>), luminosity (<L-X>), rise and decay timescales (tau(r) and tau(d)) of the flares, finding that (1) class I-II sources tend to have a high <kT>, which sometimes exceeds 5 keV, (2) the distribution of <L-X> during flares is nearly the same for all classes from similar to 10(29.5) to similar to 10(31.5) ergs(-1), although there is a marginal hint of a higher <L-X> distribution for class I than class II-III, and (3) positive and negative log-linear correlations are found between tau(r), and tau(d), and <kT> and tau(r). In order to explain these relations, we used the framework of magnetic reconnection model with heat conduction and chromospheric evaporation to formulate the observational parameters (tau(r), tau(d), and <kT>) as a function of the pre-flare (coronal) electronic density (n(c)), the half-length of the reconnected magnetic loop (L), and magnetic field strength (B). The observed correlations are well reproduced if loop lengths are nearly the same for all classes, regardless of the existence of an accretion disk. The estimated loop length is almost comparable to the typical stellar radius of these objects (10(10)-10(11) cm), which indicates that the observed flares are triggered by solar-type loops, rather than larger ones (similar to 10(12) cm) connecting the star with its inner accretion disk. The higher <kT> observed for class I sources may be explained by a slightly higher magnetic field strength (approximate to 500G) than for class II-III sources (200-300 G).

    DOI: 10.1093/pasj/55.3.653

    Web of Science

    researchmap

  • A Systematic Study of X-Ray Flares from Low-Mass Young Stellar Objects in the ρOphiuchi Star-Forming Region with Chandra

    Publications of the Astron, Society of Japan   55 ( 3 )   653 - 681   2003年6月

     詳細を見る

  • Coronal X-ray emission from an intermediate-age brown dwarf

    Y Tsuboi, Y Maeda, ED Feigelson, GP Garmire, G Chartas, K Mori, SH Pravdo

    ASTROPHYSICAL JOURNAL   587 ( 1 )   L51 - L54   2003年4月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    We report the X-ray detection of the brown dwarf (BD) companion TWA 5B in an similar or equal to12 Myr old pre-main-sequence binary system. We clearly resolve the faint companion (35 photons) separated from the X-ray luminous primary by 2" in a Chandra ACIS image. TWA 5B shows a soft X-ray spectrum with a low plasma temperature of only 0.3 keV and a constant flux during the 3 hr observation, of which the characteristics are commonly seen in the solar corona. The X-ray luminosity is 4 x 10(27) ergs s(-1) (0.1-10 keV band) or log (L-x/L-bol) = -3.4 Comparing these properties to both younger and older BDs, we discuss the evolution of the X- ray emission in BDs. During their first few megayears, they exhibit high levels of X-ray activity, as seen in higher mass pre-main-sequence stars. The level in TWA 5B is still high at t similar or equal to 12 Myr in log L-x/L-bol, while kT has already substantially cooled.

    DOI: 10.1086/375017

    Web of Science

    researchmap

  • Coronal X-ray emission from an intermediate-age brown dwarf

    Y Tsuboi, Y Maeda, ED Feigelson, GP Garmire, G Chartas, K Mori, SH Pravdo

    ASTROPHYSICAL JOURNAL   587 ( 1 )   L51 - L54   2003年4月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    We report the X-ray detection of the brown dwarf (BD) companion TWA 5B in an similar or equal to12 Myr old pre-main-sequence binary system. We clearly resolve the faint companion (35 photons) separated from the X-ray luminous primary by 2" in a Chandra ACIS image. TWA 5B shows a soft X-ray spectrum with a low plasma temperature of only 0.3 keV and a constant flux during the 3 hr observation, of which the characteristics are commonly seen in the solar corona. The X-ray luminosity is 4 x 10(27) ergs s(-1) (0.1-10 keV band) or log (L-x/L-bol) = -3.4 Comparing these properties to both younger and older BDs, we discuss the evolution of the X- ray emission in BDs. During their first few megayears, they exhibit high levels of X-ray activity, as seen in higher mass pre-main-sequence stars. The level in TWA 5B is still high at t similar or equal to 12 Myr in log L-x/L-bol, while kT has already substantially cooled.

    DOI: 10.1086/375017

    Web of Science

    researchmap

  • Coronal X-ray emission from an intermediate-age brown dwarf

    Y Tsuboi, Y Maeda, ED Feigelson, GP Garmire, G Chartas, K Mori, SH Pravdo

    ASTROPHYSICAL JOURNAL   587 ( 1 )   L51 - L54   2003年4月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    We report the X-ray detection of the brown dwarf (BD) companion TWA 5B in an similar or equal to12 Myr old pre-main-sequence binary system. We clearly resolve the faint companion (35 photons) separated from the X-ray luminous primary by 2" in a Chandra ACIS image. TWA 5B shows a soft X-ray spectrum with a low plasma temperature of only 0.3 keV and a constant flux during the 3 hr observation, of which the characteristics are commonly seen in the solar corona. The X-ray luminosity is 4 x 10(27) ergs s(-1) (0.1-10 keV band) or log (L-x/L-bol) = -3.4 Comparing these properties to both younger and older BDs, we discuss the evolution of the X- ray emission in BDs. During their first few megayears, they exhibit high levels of X-ray activity, as seen in higher mass pre-main-sequence stars. The level in TWA 5B is still high at t similar or equal to 12 Myr in log L-x/L-bol, while kT has already substantially cooled.

    DOI: 10.1086/375017

    Web of Science

    researchmap

  • Coronal X-ray emission from an intermediate-age brown dwarf

    Y Tsuboi, Y Maeda, ED Feigelson, GP Garmire, G Chartas, K Mori, SH Pravdo

    ASTROPHYSICAL JOURNAL   587 ( 1 )   L51 - L54   2003年4月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    We report the X-ray detection of the brown dwarf (BD) companion TWA 5B in an similar or equal to12 Myr old pre-main-sequence binary system. We clearly resolve the faint companion (35 photons) separated from the X-ray luminous primary by 2" in a Chandra ACIS image. TWA 5B shows a soft X-ray spectrum with a low plasma temperature of only 0.3 keV and a constant flux during the 3 hr observation, of which the characteristics are commonly seen in the solar corona. The X-ray luminosity is 4 x 10(27) ergs s(-1) (0.1-10 keV band) or log (L-x/L-bol) = -3.4 Comparing these properties to both younger and older BDs, we discuss the evolution of the X- ray emission in BDs. During their first few megayears, they exhibit high levels of X-ray activity, as seen in higher mass pre-main-sequence stars. The level in TWA 5B is still high at t similar or equal to 12 Myr in log L-x/L-bol, while kT has already substantially cooled.

    DOI: 10.1086/375017

    Web of Science

    researchmap

  • Deep near-infrared observations and identifications of Chandra sources in orion molecular clouds 2 and 3

    M Tsujimoto, K Koyama, N Kobayashi, M Goto, Y Tsuboi, AT Tokunaga

    ASTRONOMICAL JOURNAL   125 ( 3 )   1537 - 1545   2003年3月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    We conducted deep near-infrared (NIR) imaging observations of Orion molecular clouds 2 and 3 using the Quick Infrared Camera on the 88 inch (2.2 m) telescope of the University of Hawaii. Our purposes were (1) to generate a comprehensive NIR source catalog of these star-forming clouds and ( 2) to identify the NIR counterpart of the Chandra X-ray sources that have no counterpart in the Two Micron All Sky Survey (2MASS) catalog. Our J-, H-, and K-band observations are similar to2 mag deeper than those of 2MASS and match the current Chandra observation well. We detected 1448 NIR sources, for which we derived the position, the J-, H-, and K-band magnitude, and the 2MASS counterpart. Using this catalog, we identified the NIR counterpart for similar to42% of the 2MASS unidentified Chandra sources. The nature of these Chandra sources are discussed using their NIR colors and spatial distributions, and a dozen protostar and brown dwarf candidates are identified.

    DOI: 10.1086/346277

    Web of Science

    researchmap

  • Deep near-infrared observations and identifications of Chandra sources in orion molecular clouds 2 and 3

    M Tsujimoto, K Koyama, N Kobayashi, M Goto, Y Tsuboi, AT Tokunaga

    ASTRONOMICAL JOURNAL   125 ( 3 )   1537 - 1545   2003年3月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    We conducted deep near-infrared (NIR) imaging observations of Orion molecular clouds 2 and 3 using the Quick Infrared Camera on the 88 inch (2.2 m) telescope of the University of Hawaii. Our purposes were (1) to generate a comprehensive NIR source catalog of these star-forming clouds and ( 2) to identify the NIR counterpart of the Chandra X-ray sources that have no counterpart in the Two Micron All Sky Survey (2MASS) catalog. Our J-, H-, and K-band observations are similar to2 mag deeper than those of 2MASS and match the current Chandra observation well. We detected 1448 NIR sources, for which we derived the position, the J-, H-, and K-band magnitude, and the 2MASS counterpart. Using this catalog, we identified the NIR counterpart for similar to42% of the 2MASS unidentified Chandra sources. The nature of these Chandra sources are discussed using their NIR colors and spatial distributions, and a dozen protostar and brown dwarf candidates are identified.

    DOI: 10.1086/346277

    Web of Science

    researchmap

  • Deep near-infrared observations and identifications of Chandra sources in orion molecular clouds 2 and 3

    M Tsujimoto, K Koyama, N Kobayashi, M Goto, Y Tsuboi, AT Tokunaga

    ASTRONOMICAL JOURNAL   125 ( 3 )   1537 - 1545   2003年3月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    We conducted deep near-infrared (NIR) imaging observations of Orion molecular clouds 2 and 3 using the Quick Infrared Camera on the 88 inch (2.2 m) telescope of the University of Hawaii. Our purposes were (1) to generate a comprehensive NIR source catalog of these star-forming clouds and ( 2) to identify the NIR counterpart of the Chandra X-ray sources that have no counterpart in the Two Micron All Sky Survey (2MASS) catalog. Our J-, H-, and K-band observations are similar to2 mag deeper than those of 2MASS and match the current Chandra observation well. We detected 1448 NIR sources, for which we derived the position, the J-, H-, and K-band magnitude, and the 2MASS counterpart. Using this catalog, we identified the NIR counterpart for similar to42% of the 2MASS unidentified Chandra sources. The nature of these Chandra sources are discussed using their NIR colors and spatial distributions, and a dozen protostar and brown dwarf candidates are identified.

    DOI: 10.1086/346277

    Web of Science

    researchmap

  • Deep near-infrared observations and identifications of Chandra sources in orion molecular clouds 2 and 3

    M Tsujimoto, K Koyama, N Kobayashi, M Goto, Y Tsuboi, AT Tokunaga

    ASTRONOMICAL JOURNAL   125 ( 3 )   1537 - 1545   2003年3月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    We conducted deep near-infrared (NIR) imaging observations of Orion molecular clouds 2 and 3 using the Quick Infrared Camera on the 88 inch (2.2 m) telescope of the University of Hawaii. Our purposes were (1) to generate a comprehensive NIR source catalog of these star-forming clouds and ( 2) to identify the NIR counterpart of the Chandra X-ray sources that have no counterpart in the Two Micron All Sky Survey (2MASS) catalog. Our J-, H-, and K-band observations are similar to2 mag deeper than those of 2MASS and match the current Chandra observation well. We detected 1448 NIR sources, for which we derived the position, the J-, H-, and K-band magnitude, and the 2MASS counterpart. Using this catalog, we identified the NIR counterpart for similar to42% of the 2MASS unidentified Chandra sources. The nature of these Chandra sources are discussed using their NIR colors and spatial distributions, and a dozen protostar and brown dwarf candidates are identified.

    DOI: 10.1086/346277

    Web of Science

    researchmap

  • X-ray properties of young stellar objects in OMC-2 and OMC-3 from the Chandra X-ray Observatory (vol 566, pg 974, 2002)

    M Tsujimoto, K Koyama, Y Tsuboi, M Goto, N Kobayashi

    ASTROPHYSICAL JOURNAL   585 ( 1 )   602 - 602   2003年3月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    Web of Science

    researchmap

  • Radio Centimeter Emissions at a Protostellar Core in OMC-3 and its Association with X-ray and NIR

    M.Tsujimoto, K.Koyama, K.Imanishi, N.Kobayashi, M.Saitoh, Y.Tsuboi

    The Proceedings of the IAU 8th Asian-Pacific Regional Meeting   289   223 - 224   2003年1月

     詳細を見る

    記述言語:英語   出版者・発行元:ASP Conference Series  

    researchmap

  • Radio Centimeter Emissions at a Protostellar Core in OMC-3 and its Association with X-ray and NIR

    M.Tsujimoto, K.Koyama, K.Imanishi, N.Kobayashi, M.Saitoh, Y.Tsuboi

    The Proceedings of the IAU 8th Asian-Pacific Regional Meeting   289   223 - 224   2003年1月

     詳細を見る

    記述言語:英語   出版者・発行元:ASP Conference Series  

    researchmap

  • X-Rays from Class 0/I Protostars

    Abstract of the "Star Formation at High Angular Resolution", International Astronomical Union. Symposium no.221   2003年

     詳細を見る

  • X-Rays from Class 0/I Protostars

    Abstract of the "Star Formation at High Angular Resolution", International Astronomical Union. Symposium no.221   2003年

     詳細を見る

  • Deep near-infrared observations of the X-ray emitting class 0 protostar candidates in the orion molecular cloud 3

    M Tsujimoto, K Koyama, Y Tsuboi, G Chartas, M Goto, N Kobayashi, H Terada, AT Tokunaga

    ASTROPHYSICAL JOURNAL   573 ( 1 )   270 - 274   2002年7月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We obtained near-infrared (NIR) imaging with the Subaru Telescope of the class 0 protostar candidates in the Orion molecular cloud 3, two of which were discovered to have X-ray emission by the Chandra X-Ray Observatory. We found strong evidence for the class 0 nature of the X-ray sources. First, our deep K-band image shows no emission brighter than 19.6 mag from both of these X-ray sources. Since class I protostars or class II T Tauri stars should be easily detected in the NIR with this sensitivity, the lack of K-band detection suggests that they are likely much more obscured than class I protostars. Second, our H-2 v = 1-0 S(1) image shows a bubble-like feature from one of the X-ray class 0 protostar candidates, which reinforces the idea that this is a class 0 protostar. We also discuss the nature of nine NIR sources found in our deep image based on their colors, spatial coincidence with millimeter cores, and the properties of their X-ray counterparts.

    DOI: 10.1086/340559

    Web of Science

    researchmap

  • X-ray emitting young stars in the Orion Nebula

    ED Feigelson, P Broos, JA Gaffney, G Garmire, LA Hillenbrand, SH Pravdo, L Townsley, Y Tsuboi

    ASTROPHYSICAL JOURNAL   574 ( 1 )   258 - 292   2002年7月

     詳細を見る

    記述言語:英語   掲載種別:書評論文,書評,文献紹介等   出版者・発行元:IOP PUBLISHING LTD  

    The Orion Nebula Cluster and the molecular cloud in its vicinity have been observed with the ACIS-I detector on board the Chandra X-ray Observatory with 23 hr exposure in two observations. We detect 1075 X-ray sources, most with subarcsecond positional accuracy. Ninety-one percent of the sources are spatially associated with known stellar members of the cluster, and an additional 7% are newly identified deeply embedded cloud members. This provides the largest X-ray study of a premain-sequence stellar population and covers the initial mass function from brown dwarfs up to a 45 M. O star. Source luminosities span 5 orders of magnitude from log L-X similar or equal to28.0 to 33.3 ergs s(-1) in the 0.5-8 keV band, plasma energies range from 0.2 to >10 keV, and absorption ranges from log N-H < 20.0 to similar to 23.5 cm(-2). Comprehensive tables providing X-ray and stellar characteristics are provided electronically.
    We examine here the X-ray properties of Orion young stars as a function of mass; other studies of astrophysical interest will appear in companion papers. Results include: ( a) the discovery of rapid variability in the 09.5 31 M. star theta(2)A Ori, and several early B stars, inconsistent with the standard model of X-ray production in small shocks distributed throughout the radiatively accelerated wind; (b) support for the hypothesis that intermediate-mass mid-B through A type stars do not themselves produce significant X-ray emission; (c) confirmation that low-mass G through M type T Tauri stars exhibit powerful flaring but typically at luminosities considerably below the saturation level; (d) confirmation that the presence or absence of a circumstellar disk has no discernable effect on X-ray emission; (e) evidence that T Tauri plasma temperatures are often very high with T >= 100 MK, even when luminosities are modest and flaring is not evident; and (f) detection of the largest sample of pre-main-sequence very low-mass objects showing flaring levels similar to those seen in more massive T Tauri stars and a decline in magnetic activity as they evolve into L and T type brown dwarfs.

    DOI: 10.1086/340936

    Web of Science

    researchmap

  • X-ray emitting young stars in the Orion Nebula

    ED Feigelson, P Broos, JA Gaffney, G Garmire, LA Hillenbrand, SH Pravdo, L Townsley, Y Tsuboi

    ASTROPHYSICAL JOURNAL   574 ( 1 )   258 - 292   2002年7月

     詳細を見る

    記述言語:英語   掲載種別:書評論文,書評,文献紹介等   出版者・発行元:IOP PUBLISHING LTD  

    The Orion Nebula Cluster and the molecular cloud in its vicinity have been observed with the ACIS-I detector on board the Chandra X-ray Observatory with 23 hr exposure in two observations. We detect 1075 X-ray sources, most with subarcsecond positional accuracy. Ninety-one percent of the sources are spatially associated with known stellar members of the cluster, and an additional 7% are newly identified deeply embedded cloud members. This provides the largest X-ray study of a premain-sequence stellar population and covers the initial mass function from brown dwarfs up to a 45 M. O star. Source luminosities span 5 orders of magnitude from log L-X similar or equal to28.0 to 33.3 ergs s(-1) in the 0.5-8 keV band, plasma energies range from 0.2 to >10 keV, and absorption ranges from log N-H < 20.0 to similar to 23.5 cm(-2). Comprehensive tables providing X-ray and stellar characteristics are provided electronically.
    We examine here the X-ray properties of Orion young stars as a function of mass; other studies of astrophysical interest will appear in companion papers. Results include: ( a) the discovery of rapid variability in the 09.5 31 M. star theta(2)A Ori, and several early B stars, inconsistent with the standard model of X-ray production in small shocks distributed throughout the radiatively accelerated wind; (b) support for the hypothesis that intermediate-mass mid-B through A type stars do not themselves produce significant X-ray emission; (c) confirmation that low-mass G through M type T Tauri stars exhibit powerful flaring but typically at luminosities considerably below the saturation level; (d) confirmation that the presence or absence of a circumstellar disk has no discernable effect on X-ray emission; (e) evidence that T Tauri plasma temperatures are often very high with T >= 100 MK, even when luminosities are modest and flaring is not evident; and (f) detection of the largest sample of pre-main-sequence very low-mass objects showing flaring levels similar to those seen in more massive T Tauri stars and a decline in magnetic activity as they evolve into L and T type brown dwarfs.

    DOI: 10.1086/340936

    Web of Science

    researchmap

  • X-ray emitting young stars in the Orion Nebula

    ED Feigelson, P Broos, JA Gaffney, G Garmire, LA Hillenbrand, SH Pravdo, L Townsley, Y Tsuboi

    ASTROPHYSICAL JOURNAL   574 ( 1 )   258 - 292   2002年7月

     詳細を見る

    記述言語:英語   掲載種別:書評論文,書評,文献紹介等   出版者・発行元:IOP PUBLISHING LTD  

    The Orion Nebula Cluster and the molecular cloud in its vicinity have been observed with the ACIS-I detector on board the Chandra X-ray Observatory with 23 hr exposure in two observations. We detect 1075 X-ray sources, most with subarcsecond positional accuracy. Ninety-one percent of the sources are spatially associated with known stellar members of the cluster, and an additional 7% are newly identified deeply embedded cloud members. This provides the largest X-ray study of a premain-sequence stellar population and covers the initial mass function from brown dwarfs up to a 45 M. O star. Source luminosities span 5 orders of magnitude from log L-X similar or equal to28.0 to 33.3 ergs s(-1) in the 0.5-8 keV band, plasma energies range from 0.2 to >10 keV, and absorption ranges from log N-H < 20.0 to similar to 23.5 cm(-2). Comprehensive tables providing X-ray and stellar characteristics are provided electronically.
    We examine here the X-ray properties of Orion young stars as a function of mass; other studies of astrophysical interest will appear in companion papers. Results include: ( a) the discovery of rapid variability in the 09.5 31 M. star theta(2)A Ori, and several early B stars, inconsistent with the standard model of X-ray production in small shocks distributed throughout the radiatively accelerated wind; (b) support for the hypothesis that intermediate-mass mid-B through A type stars do not themselves produce significant X-ray emission; (c) confirmation that low-mass G through M type T Tauri stars exhibit powerful flaring but typically at luminosities considerably below the saturation level; (d) confirmation that the presence or absence of a circumstellar disk has no discernable effect on X-ray emission; (e) evidence that T Tauri plasma temperatures are often very high with T >= 100 MK, even when luminosities are modest and flaring is not evident; and (f) detection of the largest sample of pre-main-sequence very low-mass objects showing flaring levels similar to those seen in more massive T Tauri stars and a decline in magnetic activity as they evolve into L and T type brown dwarfs.

    DOI: 10.1086/340936

    Web of Science

    researchmap

  • X-ray emitting young stars in the Orion Nebula

    ED Feigelson, P Broos, JA Gaffney, G Garmire, LA Hillenbrand, SH Pravdo, L Townsley, Y Tsuboi

    ASTROPHYSICAL JOURNAL   574 ( 1 )   258 - 292   2002年7月

     詳細を見る

    記述言語:英語   掲載種別:書評論文,書評,文献紹介等   出版者・発行元:IOP PUBLISHING LTD  

    The Orion Nebula Cluster and the molecular cloud in its vicinity have been observed with the ACIS-I detector on board the Chandra X-ray Observatory with 23 hr exposure in two observations. We detect 1075 X-ray sources, most with subarcsecond positional accuracy. Ninety-one percent of the sources are spatially associated with known stellar members of the cluster, and an additional 7% are newly identified deeply embedded cloud members. This provides the largest X-ray study of a premain-sequence stellar population and covers the initial mass function from brown dwarfs up to a 45 M. O star. Source luminosities span 5 orders of magnitude from log L-X similar or equal to28.0 to 33.3 ergs s(-1) in the 0.5-8 keV band, plasma energies range from 0.2 to >10 keV, and absorption ranges from log N-H < 20.0 to similar to 23.5 cm(-2). Comprehensive tables providing X-ray and stellar characteristics are provided electronically.
    We examine here the X-ray properties of Orion young stars as a function of mass; other studies of astrophysical interest will appear in companion papers. Results include: ( a) the discovery of rapid variability in the 09.5 31 M. star theta(2)A Ori, and several early B stars, inconsistent with the standard model of X-ray production in small shocks distributed throughout the radiatively accelerated wind; (b) support for the hypothesis that intermediate-mass mid-B through A type stars do not themselves produce significant X-ray emission; (c) confirmation that low-mass G through M type T Tauri stars exhibit powerful flaring but typically at luminosities considerably below the saturation level; (d) confirmation that the presence or absence of a circumstellar disk has no discernable effect on X-ray emission; (e) evidence that T Tauri plasma temperatures are often very high with T >= 100 MK, even when luminosities are modest and flaring is not evident; and (f) detection of the largest sample of pre-main-sequence very low-mass objects showing flaring levels similar to those seen in more massive T Tauri stars and a decline in magnetic activity as they evolve into L and T type brown dwarfs.

    DOI: 10.1086/340936

    Web of Science

    researchmap

  • Deep near-infrared observations of the X-ray emitting class 0 protostar candidates in the orion molecular cloud 3

    M Tsujimoto, K Koyama, Y Tsuboi, G Chartas, M Goto, N Kobayashi, H Terada, AT Tokunaga

    ASTROPHYSICAL JOURNAL   573 ( 1 )   270 - 274   2002年7月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We obtained near-infrared (NIR) imaging with the Subaru Telescope of the class 0 protostar candidates in the Orion molecular cloud 3, two of which were discovered to have X-ray emission by the Chandra X-Ray Observatory. We found strong evidence for the class 0 nature of the X-ray sources. First, our deep K-band image shows no emission brighter than 19.6 mag from both of these X-ray sources. Since class I protostars or class II T Tauri stars should be easily detected in the NIR with this sensitivity, the lack of K-band detection suggests that they are likely much more obscured than class I protostars. Second, our H-2 v = 1-0 S(1) image shows a bubble-like feature from one of the X-ray class 0 protostar candidates, which reinforces the idea that this is a class 0 protostar. We also discuss the nature of nine NIR sources found in our deep image based on their colors, spatial coincidence with millimeter cores, and the properties of their X-ray counterparts.

    DOI: 10.1086/340559

    Web of Science

    researchmap

  • Deep near-infrared observations of the X-ray emitting class 0 protostar candidates in the orion molecular cloud 3

    M Tsujimoto, K Koyama, Y Tsuboi, G Chartas, M Goto, N Kobayashi, H Terada, AT Tokunaga

    ASTROPHYSICAL JOURNAL   573 ( 1 )   270 - 274   2002年7月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We obtained near-infrared (NIR) imaging with the Subaru Telescope of the class 0 protostar candidates in the Orion molecular cloud 3, two of which were discovered to have X-ray emission by the Chandra X-Ray Observatory. We found strong evidence for the class 0 nature of the X-ray sources. First, our deep K-band image shows no emission brighter than 19.6 mag from both of these X-ray sources. Since class I protostars or class II T Tauri stars should be easily detected in the NIR with this sensitivity, the lack of K-band detection suggests that they are likely much more obscured than class I protostars. Second, our H-2 v = 1-0 S(1) image shows a bubble-like feature from one of the X-ray class 0 protostar candidates, which reinforces the idea that this is a class 0 protostar. We also discuss the nature of nine NIR sources found in our deep image based on their colors, spatial coincidence with millimeter cores, and the properties of their X-ray counterparts.

    DOI: 10.1086/340559

    Web of Science

    researchmap

  • Deep near-infrared observations of the X-ray emitting class 0 protostar candidates in the orion molecular cloud 3

    M Tsujimoto, K Koyama, Y Tsuboi, G Chartas, M Goto, N Kobayashi, H Terada, AT Tokunaga

    ASTROPHYSICAL JOURNAL   573 ( 1 )   270 - 274   2002年7月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We obtained near-infrared (NIR) imaging with the Subaru Telescope of the class 0 protostar candidates in the Orion molecular cloud 3, two of which were discovered to have X-ray emission by the Chandra X-Ray Observatory. We found strong evidence for the class 0 nature of the X-ray sources. First, our deep K-band image shows no emission brighter than 19.6 mag from both of these X-ray sources. Since class I protostars or class II T Tauri stars should be easily detected in the NIR with this sensitivity, the lack of K-band detection suggests that they are likely much more obscured than class I protostars. Second, our H-2 v = 1-0 S(1) image shows a bubble-like feature from one of the X-ray class 0 protostar candidates, which reinforces the idea that this is a class 0 protostar. We also discuss the nature of nine NIR sources found in our deep image based on their colors, spatial coincidence with millimeter cores, and the properties of their X-ray counterparts.

    DOI: 10.1086/340559

    Web of Science

    researchmap

  • 世界の研究室から「アパラチア山麓発最先端の宇宙像」

    坪井陽子

    日経サイエンス   ( 5月号 )   3   2002年5月

     詳細を見る

    記述言語:日本語   掲載種別:記事・総説・解説・論説等(その他)   出版者・発行元:日本経済新聞社  

    researchmap

  • Skylight「チャンドラで捉えた星の産声」

    坪井陽子

    天文月報   95 ( 2 )   77 - 83   2002年2月

     詳細を見る

    記述言語:日本語   掲載種別:記事・総説・解説・論説等(その他)   出版者・発行元:日本天文学会  

    researchmap

  • X-ray probing for protostars

    Y.Tsuboi

    The Astronomical Herald   95 ( 2 )   77 - 83   2002年2月

     詳細を見る

    記述言語:英語   出版者・発行元:ARI  

    researchmap

  • X-ray properties of young stellar objects in OMC-2 and OMC-3 from the Chandra X-ray observatory

    M Tsujimoto, K Koyama, Y Tsuboi, M Goto, N Kobayashi

    ASTROPHYSICAL JOURNAL   566 ( 2 )   974 - 981   2002年2月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    We report X-ray results of the Chandra observation of OMC-2 and OMC-3. A deep exposure of similar to100 ks detects similar to400 X-ray sources in the field of view of the ACIS array, providing one of the largest X-ray catalogs in a star-forming region. Coherent studies of the source detection, time variability, and energy spectra are performed. We classify the X-ray sources into Class I, Class II, and Class III + MS based on the J-, H-, and K-band colors of their near-infrared counterparts and discuss the X-ray properties (temperature, absorption, and time variability) along these evolutionary phases.

    DOI: 10.1086/338110

    Web of Science

    researchmap

  • X-ray properties of young stellar objects in OMC-2 and OMC-3 from the Chandra X-ray observatory

    M Tsujimoto, K Koyama, Y Tsuboi, M Goto, N Kobayashi

    ASTROPHYSICAL JOURNAL   566 ( 2 )   974 - 981   2002年2月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    We report X-ray results of the Chandra observation of OMC-2 and OMC-3. A deep exposure of similar to100 ks detects similar to400 X-ray sources in the field of view of the ACIS array, providing one of the largest X-ray catalogs in a star-forming region. Coherent studies of the source detection, time variability, and energy spectra are performed. We classify the X-ray sources into Class I, Class II, and Class III + MS based on the J-, H-, and K-band colors of their near-infrared counterparts and discuss the X-ray properties (temperature, absorption, and time variability) along these evolutionary phases.

    DOI: 10.1086/338110

    Web of Science

    researchmap

  • X-ray probing for protostars

    Y.Tsuboi

    The Astronomical Herald   95 ( 2 )   77 - 83   2002年2月

     詳細を見る

    記述言語:英語   出版者・発行元:ARI  

    researchmap

  • Chandra Detection of a Middle Age Brown Dwarf TWA 5B

    Y.Tsuboi, G.Chartas, E.D.Feigelson, G.Garmire, Y.Maeda, K.Mori, L.Townsley, S.Pravdo

    Stellar Coronae in the Chandra and XMM-NEWTON Era, ASP Conference Proceedings   277   255- - 255   2002年1月

     詳細を見る

    記述言語:英語   出版者・発行元:Astronomical Society of the Pacific  

    researchmap

  • Chandra/ACIS Observations of the 30 Doradus Star-Forming Complex

    Abstract of the American Physical Society, April Meeting   2002年

     詳細を見る

  • Chandra Detection of a Middle Age Brown Dwarf TWA 5B

    Stellar Coronae in the Chandra and XMM-NEWTON Era, ASP Conference Proceedings   277   255-   2002年

     詳細を見る

  • Chandra/ACIS Observations of the 30 Doradus Star-Forming Complex

    Abstract of the American Physical Society, April Meeting   2002年

     詳細を見る

  • Discovery of X-rays from the protostellar outflow object HH2

    SH Pravdo, ED Feigelson, G Garmire, Y Maeda, Y Tsuboi, J Bally

    NATURE   413 ( 6857 )   708 - 711   2001年10月

     詳細を見る

    記述言語:英語   出版者・発行元:MACMILLAN PUBLISHERS LTD  

    Herbig-Haro (HH) objects have been known(1,2) for 50 years to be luminous condensations of gas in star-forming regions, but their underlying physical nature is still being elucidated. Previously suggested models encompass newborn stars(3), stellar winds clashing with nebular material(4), dense pockets of interstellar gas excited by shocks from outflows(5), and interstellar 'bullets' (ref. 6). Recent progress has been made with the jet-induced shock model(7), in which material streams out of young stellar objects and collides with the surrounding interstellar medium. A clear prediction of this model is that the most energetic Herbig-Haro objects will emit X-rays, although they have not hitherto been detected(8). Here we report the discovery of X-ray emission from one of the brightest and closest Herbig-Haro objects, HH2, at a level consistent with the model predictions. We conclude that this Herbig-Haro object contains shock-heated material located at or near its leading edge with a temperature of about 10(6) K.

    DOI: 10.1038/35099508

    Web of Science

    PubMed

    researchmap

  • ASCA observations on two molecular cloud cores in the perseus complex

    S Yamauchi, Y Tsuboi, K Koyama

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   53 ( 5 )   885 - 892   2001年10月

     詳細を見る

    記述言語:英語   出版者・発行元:OXFORD UNIV PRESS  

    DOI: 10.1093/pasj/53.5.885

    Web of Science

    researchmap

  • ASCA observations on two molecular cloud cores in the perseus complex

    S Yamauchi, Y Tsuboi, K Koyama

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   53 ( 5 )   885 - 892   2001年10月

     詳細を見る

    記述言語:英語   出版者・発行元:OXFORD UNIV PRESS  

    DOI: 10.1093/pasj/53.5.885

    Web of Science

    researchmap

  • Discovery of X-rays from the protostellar outflow object HH2

    SH Pravdo, ED Feigelson, G Garmire, Y Maeda, Y Tsuboi, J Bally

    NATURE   413 ( 6857 )   708 - 711   2001年10月

     詳細を見る

    記述言語:英語   出版者・発行元:MACMILLAN PUBLISHERS LTD  

    Herbig-Haro (HH) objects have been known(1,2) for 50 years to be luminous condensations of gas in star-forming regions, but their underlying physical nature is still being elucidated. Previously suggested models encompass newborn stars(3), stellar winds clashing with nebular material(4), dense pockets of interstellar gas excited by shocks from outflows(5), and interstellar 'bullets' (ref. 6). Recent progress has been made with the jet-induced shock model(7), in which material streams out of young stellar objects and collides with the surrounding interstellar medium. A clear prediction of this model is that the most energetic Herbig-Haro objects will emit X-rays, although they have not hitherto been detected(8). Here we report the discovery of X-ray emission from one of the brightest and closest Herbig-Haro objects, HH2, at a level consistent with the model predictions. We conclude that this Herbig-Haro object contains shock-heated material located at or near its leading edge with a temperature of about 10(6) K.

    DOI: 10.1038/35099508

    Web of Science

    PubMed

    researchmap

  • A Hint of Star-disk Interaction: Quasi-periodic Flares from a Protostar

    Y.Tsuboi, N.Grosso, T.Montmerle, K.Imanishi, K.Koyama

    11th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun, ASP Conference Proceedings   223   1183 - 1188   2001年9月

     詳細を見る

    記述言語:英語   出版者・発行元:Astronomical Society of the Pacific  

    researchmap

  • A Hint of Star-disk Interaction: Quasi-periodic Flares from a Protostar

    Y.Tsuboi, N.Grosso, T.Montmerle, K.Imanishi, K.Koyama

    11th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun, ASP Conference Proceedings   223   1183 - 1188   2001年9月

     詳細を見る

    記述言語:英語   出版者・発行元:Astronomical Society of the Pacific  

    researchmap

  • Chandra Observation of the ρ Oph Cloud

    The Astrophysical Journal   557 ( 2 )   747 - 760   2001年8月

     詳細を見る

    記述言語:英語  

    Web of Science

    researchmap

  • Chandra observation of the rho Ophiuchi cloud

    K Imanishi, K Koyama, Y Tsuboi

    ASTROPHYSICAL JOURNAL   557 ( 2 )   747 - 760   2001年8月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    We observed a 17 ' x 17 ' region of the rho Oph molecular cloud, using the ACIS-I array on board the Chandra X-Ray Observatory. A 100 ks exposure observation revealed similar to 100 X-ray sources above the detection limit of similar to 10(28) ergs s(-1). About two-thirds of the X-ray sources are identified with an optical and/or IR counterpart, including significant numbers of class I, II, and III sources and a few brown dwarfs. The X-ray detection rate of class I sources is a surprisingly high 70%. Many X-ray flares, possibly because of the magnetic activity, are found from all of the classes. We make systematic spectral studies of the quiescent and flare X-rays for all the X-ray sources. The X-ray temperatures and absorptions of class I sources are generally larger than those of class II and III sources. In addition, X-ray flares from class I sources show slightly higher duty ratio, temperature, and luminosity than those of more evolved classes. We further give brief results on brown dwarfs, sources in a younger phase than class I, unclassified, and unidentified sources. Details for several selected young stellar objects, including the first detection of a neutral iron line (6.4 keV) from a class I source (YLW 16A), are separately addressed.

    Web of Science

    researchmap

  • Discovery of X-rays from class 0 protostar candidates in OMC-3

    Y Tsuboi, K Koyama, K Hamaguchi, K Tatematsu, Y Sekimoto, J Bally, B Reipurth

    ASTROPHYSICAL JOURNAL   554 ( 2 )   734 - 741   2001年6月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    We have observed the Orion Molecular Clouds 2 and 3 (OMC-2 and OMC-3) with the Chandra X-Ray Observatory (CXO). The northern part of OMC-3 is found to be particularly rich in new X-ray features; four hard X-ray sources are located in and along the filament of cloud cores. Two sources coincide positionally with the submillimeter-millimeter dust condensations of MMS 2 and 3 or an outflow radio source VLA 1, which are in a very early phase of star formation. The X-ray spectra of these sources show an absorption column of (1-3) x 10(23) H cm(-2). Assuming a moderate temperature plasma, the X-ray luminosity in the 0.5-10 keV band is estimated to be similar to 10(30) ergs s(-1) at a distance of 450 pc. From the large absorption, positional coincidence, and moderate luminosity, we infer that the hard X-rays are coming from very young stellar objects embedded in the molecular cloud cores. We found another hard X-ray source near the edge of the dust filament. The extremely high absorption of 3 x 10(23) H cm(-2) indicates that the source must be surrounded by dense gas, suggesting that it is either a young stellar object in an early accretion phase or a Type II AGN (e.g., a Seyfert 2), although no counterpart is found at any other wavelength. In contrast to the hard X-ray sources, soft X-ray sources are found spread around the dust filaments, most of which are identified with IR sources in the T. Tauri phase.

    DOI: 10.1086/321392

    Web of Science

    researchmap

  • Discovery of X-rays from class 0 protostar candidates in OMC-3

    Y Tsuboi, K Koyama, K Hamaguchi, K Tatematsu, Y Sekimoto, J Bally, B Reipurth

    ASTROPHYSICAL JOURNAL   554 ( 2 )   734 - 741   2001年6月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    We have observed the Orion Molecular Clouds 2 and 3 (OMC-2 and OMC-3) with the Chandra X-Ray Observatory (CXO). The northern part of OMC-3 is found to be particularly rich in new X-ray features; four hard X-ray sources are located in and along the filament of cloud cores. Two sources coincide positionally with the submillimeter-millimeter dust condensations of MMS 2 and 3 or an outflow radio source VLA 1, which are in a very early phase of star formation. The X-ray spectra of these sources show an absorption column of (1-3) x 10(23) H cm(-2). Assuming a moderate temperature plasma, the X-ray luminosity in the 0.5-10 keV band is estimated to be similar to 10(30) ergs s(-1) at a distance of 450 pc. From the large absorption, positional coincidence, and moderate luminosity, we infer that the hard X-rays are coming from very young stellar objects embedded in the molecular cloud cores. We found another hard X-ray source near the edge of the dust filament. The extremely high absorption of 3 x 10(23) H cm(-2) indicates that the source must be surrounded by dense gas, suggesting that it is either a young stellar object in an early accretion phase or a Type II AGN (e.g., a Seyfert 2), although no counterpart is found at any other wavelength. In contrast to the hard X-ray sources, soft X-ray sources are found spread around the dust filaments, most of which are identified with IR sources in the T. Tauri phase.

    DOI: 10.1086/321392

    Web of Science

    researchmap

  • Discovery of X-rays from Class 0 Protostar Candidates

    Y.Tsuboi, K.Koyama, K.Hamaguchi, K.tatematsu, Y.Sekimoto, J.Bally, B.Reipurth

    New Century of X-ray Astronomy, ASP Conference Proceedings   251   18- - 18   2001年1月

     詳細を見る

    記述言語:英語   出版者・発行元:Astronomical Society of the Pacific  

    researchmap

  • ASCA Observations of Two Molecular Cloud Cores in the Perseus Molecular Cloud Complex

    S.Yamauchi, Y.Tsuboi, K.Koyama

    New Century of X-ray Astronomy, ASP Conference Proceedings   251   286- - 286   2001年1月

     詳細を見る

    記述言語:英語   出版者・発行元:Astronomical Society of the Pacific  

    researchmap

  • XMM-Newton EPIC Observations of OMC-2/3 region

    Bulletin of the American Astronomical Society   34   564   2001年

     詳細を見る

  • Magnetic flaring in the young Sun and implications for solar nebula solids

    Abstract of the Two Years of Science with Chandra   2001年

     詳細を見る

  • X-rays from the Brown Dwarf BD TWA-5B

    Abstract of the Two Years of Science with Chandra   2001年

     詳細を見る

  • SUBARU follow-up observation of class 0 sources detected by Chandra X-ray observatory

    M Tsujimoto, K Koyama, M Goto, H Terada, N Kobayashi, Y Tsuboi

    NEW CENTURY OF X-RAY ASTRONOMY   251   282 - 283   2001年

     詳細を見る

    記述言語:英語   出版者・発行元:ASTRONOMICAL SOC PACIFIC  

    Follow-up observations of the X-ray emitting class 0 candidates were performed in the near infrared hand using the SUBARU telescope. We set the upper limit on the K-band magnitude of these candidates, and found a jet-like feature in H-2 v = 1-0 S(1) band, originating from one of these candidates. These sources, therefore, arc, more likely to be class 0s, and thus are the first discoveries of the X-ray emitting class 0 objects.

    Web of Science

    researchmap

  • Chandra observation of the rho Oph star-forming region

    K Imanishi, K Koyama, Y Tsuboi

    NEW CENTURY OF X-RAY ASTRONOMY   251   246 - 247   2001年

     詳細を見る

    記述言語:英語   出版者・発行元:ASTRONOMICAL SOC PACIFIC  

    We observed a 17' x 17' region of the p Oph molecular cloud, using the ACIS-I array onboard the Chandra X-ray Observatory (CXO). A 100-ks exposure observation revealed similar to hundred X-ray sources above the detection limit of similar to 10(28) ergs s(-1), of which 18 are class I sources and 29 have no counterpart in any other wave lengths. The X-ray detection rate of class 1 sources is a surprisingly high 70 %. Many X-ray flares, possibly due to the magnetic activity, are found from all of the classes. Difference in X-ray property between class I and class II/III sources, X-ray detection from brown dwarfs, and possible nature of unidentified sources are also discussed. More information is available from Imanishi et al. (2001 ApJ in press, astro-ph/0104190).

    Web of Science

    researchmap

  • Discovery of X-rays from Class 0 protostar candidates

    Y Tsuboi, K Koyama, K Hamaguchi

    NEW CENTURY OF X-RAY ASTRONOMY   251   18 - 21   2001年

     詳細を見る

    記述言語:英語   出版者・発行元:ASTRONOMICAL SOC PACIFIC  

    This paper reports discovery of X-ray emission from Class 0 protostar candidates, which are youngest X-ray stars ever detected. Class 0 is thought to be the evolutionary phase just after the birth of a star, and the ages are less than 10(5) years. The central stars are deeply embedded in dust condensations and thus never detected in any other wavelengths. The X-ray spectra are heavily absorbed, possibly by large amounts of gas and dust around the central stars. This high absorption proves that the X rays come really from the center of the dust condensations, i.e. from the central stars. Assuming a moderate temperature plasma, the X-ray luminosities in the 0.5-10 keV band are all similar to10(30) erg s(-1) at a distance of 450 pc, which are common in the older Class 1, 11 and III phases.

    Web of Science

    researchmap

  • X-rays From A Protostellar Outflow: HH 2

    Bulletin of the American Astronomical Society   33 ( 2 )   824   2001年

     詳細を見る

  • Magnetic flaring in the young Sun and implications for solar nebula solids

    Abstract of the Two Years of Science with Chandra   2001年

     詳細を見る

  • X-rays from the Brown Dwarf BD TWA-5B

    Abstract of the Two Years of Science with Chandra   2001年

     詳細を見る

  • XMM-Newton EPIC Observations of OMC-2/3 region

    Bulletin of the American Astronomical Society   34   564   2001年

     詳細を見る

  • ASCA observations of two molecular cloud cores in the Perseus molecular cloud complex

    S Yamauchi, Y Tsuboi, K Koyama

    NEW CENTURY OF X-RAY ASTRONOMY   251   286 - 287   2001年

     詳細を見る

    記述言語:英語   出版者・発行元:ASTRONOMICAL SOC PACIFIC  

    We report ASCA observations of two molecular cloud cores in the Perseus molecular cloud complex, Barnard I and the core containing a Class 0 protostar, IRAS 03282+3035. We detected 4 X-ray sources and found counterparts for two of them. We found no X-ray emission from young IRAS sources, IRAS 03282+3035 and IRAS 03301+3057, and obtained upper limits of their X-ray emissions.

    Web of Science

    researchmap

  • SUBARU follow-up observation of class 0 sources detected by Chandra X-ray observatory

    M Tsujimoto, K Koyama, M Goto, H Terada, N Kobayashi, Y Tsuboi

    NEW CENTURY OF X-RAY ASTRONOMY   251   282 - 283   2001年

     詳細を見る

    記述言語:英語   出版者・発行元:ASTRONOMICAL SOC PACIFIC  

    Follow-up observations of the X-ray emitting class 0 candidates were performed in the near infrared hand using the SUBARU telescope. We set the upper limit on the K-band magnitude of these candidates, and found a jet-like feature in H-2 v = 1-0 S(1) band, originating from one of these candidates. These sources, therefore, arc, more likely to be class 0s, and thus are the first discoveries of the X-ray emitting class 0 objects.

    Web of Science

    researchmap

  • Chandra Observation of the ρ Oph Star-Forming Region

    New Century of X-ray Astronomy, ASP Conference Proceedings   251   246 - 247   2001年

     詳細を見る

    記述言語:英語  

    Web of Science

    researchmap

  • X-rays From A Protostellar Outflow: HH 2

    Bulletin of the American Astronomical Society   33 ( 2 )   824   2001年

     詳細を見る

  • X-ray emission from intermediate- to high-mass pre-main sequence stars

    K Hamaguchi, H Terada, A Bamba, K Imanishi, M Ueno, K Koyama, S Yamauchi, Y Tsuboi

    FROM DARKNESS TO LIGHT: ORIGIN AND EVOLUTION OF YOUNG STELLAR CLUSTERS   243   627 - 632   2001年

     詳細を見る

    記述言語:英語   出版者・発行元:ASTRONOMICAL SOC PACIFIC  

    We present the ASCA observational results of intermediate mass to high mass pre-main-sequence stars. Seven objects in five fields were observed. Most sources exhibited significant time variability including flaring events, which suggests some magnetic activities on these stars. In the spectral analysis, younger sources in about 10(5)-years-old have higher plasma temperatures than 2keV whereas older sources have lower ones in our limited samples. The possible magnetic amplification mechanism is also discussed.

    Web of Science

    researchmap

  • Chandra X-Ray Observatory study of the Orion Nebula cluster and BN/KL region

    G Garmire, ED Feigelson, P Broos, LA Hillenbrand, SH Pravdo, L Townsley, Y Tsuboi

    ASTRONOMICAL JOURNAL   120 ( 3 )   1426 - 1435   2000年9月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    About 1000 X-ray emitting young pre-main-sequence (PMS) stars distributed in mass from similar to 0.05 M. brown dwarfs to a similar to 50 M. O star are detected in an image of the Orion Nebula obtained with the Advanced CCD Imaging Spectrometer on board the Chandra X-Ray Observatory. This is the richest field of sources ever obtained in X-ray astronomy. Individual X-ray luminosities in the Orion Nebula cluster range from the sensitivity limit of 2 x 10(28) ergs s(-1) to similar to 10(32) ergs s(-1). ACIS sources include 85%-90% of V < 20 stars, plus a lower but substantial fraction of deeply embedded stars with extinctions as high as A(V) similar or equal to 60. The relationships between X-ray and other PMS stellar properties suggest that X-ray luminosity of lower-mass PMS stars depends more on mass, and possibly stellar rotation, than on bolometric luminosity, as widely reported. In a subsample of 17 unabsorbed stars with mass similar or equal to 1 M., X-ray luminosities are constant at a high level around L-x similar or equal to 2 x 10(30) ergs s(-1) for the first similar or equal to 2 Myr while descending the convective Hayashi track, but diverge during the 2-10 Myr phase with X-ray emission plummeting in some stars but remaining high in others. This behavior is consistent with the distribution of X-ray luminosities on the zero-age main sequence and with current theories of their rotational history and magnetic dynamos.
    The sources in the Becklin-Neugebauer/Kleinman-low region of massive star formation are discussed in detail. They include both unabsorbed and embedded low-mass members of the Orion Nebula cluster, the luminous infrared Source n, and a class of sources without optical or infrared counterparts that may be new magnetically active embedded PMS stars. Several X-ray sources are also variable radio emitters, an association often seen in magnetically active PMS stars. Faint X-ray emission is seen close to, but apparently not coincident with, the Becklin-Neugebauer object. Its nature is not clear.

    Web of Science

    researchmap

  • Chandra X-Ray Observatory study of the Orion Nebula cluster and BN/KL region

    G Garmire, ED Feigelson, P Broos, LA Hillenbrand, SH Pravdo, L Townsley, Y Tsuboi

    ASTRONOMICAL JOURNAL   120 ( 3 )   1426 - 1435   2000年9月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    About 1000 X-ray emitting young pre-main-sequence (PMS) stars distributed in mass from similar to 0.05 M. brown dwarfs to a similar to 50 M. O star are detected in an image of the Orion Nebula obtained with the Advanced CCD Imaging Spectrometer on board the Chandra X-Ray Observatory. This is the richest field of sources ever obtained in X-ray astronomy. Individual X-ray luminosities in the Orion Nebula cluster range from the sensitivity limit of 2 x 10(28) ergs s(-1) to similar to 10(32) ergs s(-1). ACIS sources include 85%-90% of V < 20 stars, plus a lower but substantial fraction of deeply embedded stars with extinctions as high as A(V) similar or equal to 60. The relationships between X-ray and other PMS stellar properties suggest that X-ray luminosity of lower-mass PMS stars depends more on mass, and possibly stellar rotation, than on bolometric luminosity, as widely reported. In a subsample of 17 unabsorbed stars with mass similar or equal to 1 M., X-ray luminosities are constant at a high level around L-x similar or equal to 2 x 10(30) ergs s(-1) for the first similar or equal to 2 Myr while descending the convective Hayashi track, but diverge during the 2-10 Myr phase with X-ray emission plummeting in some stars but remaining high in others. This behavior is consistent with the distribution of X-ray luminosities on the zero-age main sequence and with current theories of their rotational history and magnetic dynamos.
    The sources in the Becklin-Neugebauer/Kleinman-low region of massive star formation are discussed in detail. They include both unabsorbed and embedded low-mass members of the Orion Nebula cluster, the luminous infrared Source n, and a class of sources without optical or infrared counterparts that may be new magnetically active embedded PMS stars. Several X-ray sources are also variable radio emitters, an association often seen in magnetically active PMS stars. Faint X-ray emission is seen close to, but apparently not coincident with, the Becklin-Neugebauer object. Its nature is not clear.

    Web of Science

    researchmap

  • 海外研究室事情(7)「米国ペンシルバニア州立大学、天文及び天体物理学科」

    前田良知, 坪井陽子

    天文月報   93 ( 7 )   390 - 931   2000年7月

     詳細を見る

    記述言語:日本語   掲載種別:記事・総説・解説・論説等(その他)   出版者・発行元:日本天文学会  

    researchmap

  • Quasi-periodic X-ray flares from the protostar YLW 15

    Y Tsuboi, K Imanishi, K Koyama, N Grosso, T Montmerle

    ASTROPHYSICAL JOURNAL   532 ( 2 )   1089 - 1096   2000年4月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    With ASCA, we have detected three X-ray flares from the class I protostar YLW 15. The flares occurred every similar to 20 hr and showed an exponential decay with time constant 30-60 ks. The X-ray spectra are explained by a thin thermal plasma emission. The plasma temperature shows a fast rise and slow decay for each flare with kT(peak) similar to 4-6 keV. The emission measure of the plasma shows this time profile only for the first flare, and remains almost constant during the second and third flares, at the level of the tail of the first flare. The peak flare luminosities, L-X,L-peak, were similar to 5-20 x 10(31) ergs s(-1), which are among the brightest X-ray luminosities observed to date for class I protostars. The total energy released in each flare was 3-6 x 10(36) ergs. The first flare is well reproduced by the quasi-static cooling model, which is based on solar flares, and it suggests that the plasma cools mainly radiatively, confined by a semicircular magnetic loop of length similar to 14 R-circle dot with diameter-to-length ratio similar to 0.07. The two subsequent flares were consistent with the reheating of the same magnetic structure and the periodicity of the flares imply that the reheating events of the same magnetic loop originate in an interaction between the star and the disk due to the differential rotation.

    Web of Science

    researchmap

  • Rotation and X-ray emission from protostars

    T Montmerle, N Grosso, Y Tsuboi, K Koyama

    ASTROPHYSICAL JOURNAL   532 ( 2 )   1097 - 1110   2000年4月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    The ASCA satellite has recently detected variable hard X-ray emission from two class I protostars in the rho Oph cloud, YLW 15 (IRS 43) and WL 6, with a characteristic timescale of similar to 20 hr. In YLW 15, the X-ray emission is in the form of quasi-periodic energetic flares, which we explain in terms of strong magnetic shearing and reconnection between the central star and the accretion disk. The flare modeling, based on the solar analogy, gives us access to the size of the magnetic structures, which in turn allows us to calculate the rotation parameters of the star and the disk. In WL 6, X-ray flaring is rotationally modulated and appears to be more like the solar-type magnetic activity ubiquitous on T Tauri stars. On the basis of these observations, we find that YLW 15 is a fast rotator (near break-up), while WL 6 rotates with a significantly longer period. We thus use X-ray flaring as a "clock" to measure the rotation of protostars. With the help of the mass-radius relation on the stellar "birthline," we derive masses of M-* similar to 2 M-circle dot and less than or similar to 0.4 M-circle dot for the central stars of YLW 15 and WL 6, respectively. YLW 15 thus appears to be a future A star. In the long term, the magnetic interactions between the star and the disk result in magnetic braking and angular momentum loss of the star. A comparison of the rotation behavior of YLW 15 and WL 6 confirms that for solar-mass stars magnetic braking takes place on timescales t(br) similar to a few x 10(5) yr, i.e., of the same order as the estimated duration of the class I protostar stage. The main parameter determining t(br) turns out to be the stellar mass, so that close to the birthline there must be a mass-rotation relation, t(br) similar to proportional to M-*, such that stars with M-* greater than or similar to 1-2 M-circle dot are fast rotators, while their lower mass counterparts have had the time to spin down and reach synchronous rotation with the inner surrounding accretion disk. The rapid rotation and strong star-disk magnetic interactions of YLW 15 also naturally explain the observation of "superflares" of X-ray luminosities as high as L-X greater than or similar to 10(33)-10(34) ergs s(-1) during a few hours, while at the WL 6 stage the lower X-ray luminosities are likely to be of purely stellar origin. The mass-rotation relation through magnetic braking may also explain why so few class I protostars have been detected in X-rays to date, and why they all lie in clusters. In the case of YLW 15, and perhaps also in other protostars, a hot coronal wind (T similar to 10(6) K) may be responsible for the VLA thermal radio emission. This paper thus proposes the first clues to the magnetic properties of protostars, which govern their rotation status and evolution.

    Web of Science

    researchmap

  • Quasi-periodic X-ray flares from the protostar YLW 15

    Y Tsuboi, K Imanishi, K Koyama, N Grosso, T Montmerle

    ASTROPHYSICAL JOURNAL   532 ( 2 )   1089 - 1096   2000年4月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    With ASCA, we have detected three X-ray flares from the class I protostar YLW 15. The flares occurred every similar to 20 hr and showed an exponential decay with time constant 30-60 ks. The X-ray spectra are explained by a thin thermal plasma emission. The plasma temperature shows a fast rise and slow decay for each flare with kT(peak) similar to 4-6 keV. The emission measure of the plasma shows this time profile only for the first flare, and remains almost constant during the second and third flares, at the level of the tail of the first flare. The peak flare luminosities, L-X,L-peak, were similar to 5-20 x 10(31) ergs s(-1), which are among the brightest X-ray luminosities observed to date for class I protostars. The total energy released in each flare was 3-6 x 10(36) ergs. The first flare is well reproduced by the quasi-static cooling model, which is based on solar flares, and it suggests that the plasma cools mainly radiatively, confined by a semicircular magnetic loop of length similar to 14 R-circle dot with diameter-to-length ratio similar to 0.07. The two subsequent flares were consistent with the reheating of the same magnetic structure and the periodicity of the flares imply that the reheating events of the same magnetic loop originate in an interaction between the star and the disk due to the differential rotation.

    Web of Science

    researchmap

  • Rotation and X-ray emission from protostars

    T Montmerle, N Grosso, Y Tsuboi, K Koyama

    ASTROPHYSICAL JOURNAL   532 ( 2 )   1097 - 1110   2000年4月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    The ASCA satellite has recently detected variable hard X-ray emission from two class I protostars in the rho Oph cloud, YLW 15 (IRS 43) and WL 6, with a characteristic timescale of similar to 20 hr. In YLW 15, the X-ray emission is in the form of quasi-periodic energetic flares, which we explain in terms of strong magnetic shearing and reconnection between the central star and the accretion disk. The flare modeling, based on the solar analogy, gives us access to the size of the magnetic structures, which in turn allows us to calculate the rotation parameters of the star and the disk. In WL 6, X-ray flaring is rotationally modulated and appears to be more like the solar-type magnetic activity ubiquitous on T Tauri stars. On the basis of these observations, we find that YLW 15 is a fast rotator (near break-up), while WL 6 rotates with a significantly longer period. We thus use X-ray flaring as a "clock" to measure the rotation of protostars. With the help of the mass-radius relation on the stellar "birthline," we derive masses of M-* similar to 2 M-circle dot and less than or similar to 0.4 M-circle dot for the central stars of YLW 15 and WL 6, respectively. YLW 15 thus appears to be a future A star. In the long term, the magnetic interactions between the star and the disk result in magnetic braking and angular momentum loss of the star. A comparison of the rotation behavior of YLW 15 and WL 6 confirms that for solar-mass stars magnetic braking takes place on timescales t(br) similar to a few x 10(5) yr, i.e., of the same order as the estimated duration of the class I protostar stage. The main parameter determining t(br) turns out to be the stellar mass, so that close to the birthline there must be a mass-rotation relation, t(br) similar to proportional to M-*, such that stars with M-* greater than or similar to 1-2 M-circle dot are fast rotators, while their lower mass counterparts have had the time to spin down and reach synchronous rotation with the inner surrounding accretion disk. The rapid rotation and strong star-disk magnetic interactions of YLW 15 also naturally explain the observation of "superflares" of X-ray luminosities as high as L-X greater than or similar to 10(33)-10(34) ergs s(-1) during a few hours, while at the WL 6 stage the lower X-ray luminosities are likely to be of purely stellar origin. The mass-rotation relation through magnetic braking may also explain why so few class I protostars have been detected in X-rays to date, and why they all lie in clusters. In the case of YLW 15, and perhaps also in other protostars, a hot coronal wind (T similar to 10(6) K) may be responsible for the VLA thermal radio emission. This paper thus proposes the first clues to the magnetic properties of protostars, which govern their rotation status and evolution.

    Web of Science

    researchmap

  • X-ray spectral study of the most massive HII region NGC3603

    Abstract of the High-mass Star Formation: An Origin in Clusters?   84   2000年

     詳細を見る

  • X-ray emission from high-mass pre-main-sequence stars

    Abstract of the High-mass Star Formation: An Origin in Clusters?   57   2000年

     詳細を見る

  • Discovery of Hard X-rays from Class 0 candidates in the Orion Molecular Cloud 2/3 region with Chandra

    Bulletin of the American Astronomical Society   32 ( 3 )   1256   2000年

     詳細を見る

  • Some Data Analysis Technique for Chandra ACIS

    Bulletin of the American Astronomical Society   32 ( 3 )   1227   2000年

     詳細を見る

  • Chandra Deep Observation of the rho Ophiuchi Dark Cloud

    Bulletin of the American Astronomical Society   32 ( 3 )   1256   2000年

     詳細を見る

  • Chandra/ACIS Observations of Protostars

    Bulletin of the American Astronomical Society   32 ( 4 )   1597   2000年

     詳細を見る

  • Hard X-ray detection from the core of the Monoceros R2 star forming region

    K Hamaguchi, Y Tsuboi, K Koyama

    BROAD BAND X-RAY SPECTRA OF COSMIC SOURCES   25 ( 3-4 )   531 - 534   2000年

     詳細を見る

    記述言語:英語   出版者・発行元:PERGAMON PRESS LTD  

    We report on the hard X-ray detection from the core of the Monoceros R2 giant molecular cloud. The temperature is extremely high of about 5.5 keV in quiescent state. The strongest source among hard sources is associated with molecular core and suffered deep absorption. A hard X-ray flare near the core is also observed. The temperature is also extremely high. Strong Ca and Fe lines are observed in flare spectrum, and the energies are significantly lower than those of usual plasma model. The flare spectrum show some differences from those of low-mass young stars. It might be evidence of the X-rays from a high-mass protostar. (C) 2000 COSPAR. Published by Elsevier Science Ltd.

    Web of Science

    researchmap

  • Chandra/ACIS Spectra of the 30 Doradus Star Forming Region

    Bulletin of the American Astronomical Society   32 ( 4 )   1594   2000年

     詳細を見る

  • Quasi-periodic X-ray flares on protostar YLW15

    Y Tsuboi, N Grosso, K Imanishi, K Koyama, T Montmerle

    BROAD BAND X-RAY SPECTRA OF COSMIC SOURCES   25 ( 3-4 )   535 - 538   2000年

     詳細を見る

    記述言語:英語   出版者・発行元:PERGAMON PRESS LTD  

    We detected three intermittent X-ray flares from a protostar YLSY15. Each flare occurred every similar to 20 hours, and showed an exponential decay of time constant 30-60 ks. The time-sliced X-ray spectra are all explained by a thin thermal plasma emission. The plasma temperature shows a fast-rise and a slow-decay for each flare, while the emission measure of the plasma increases only at the beginning of the first flare and is almost constant during the second and third hares. Thus the X-rays are attributable to a single plasma produced by the first large flare, then the plasma is re-heated quasi-periodically. The re-heating interval is significantly shorter than the spin periods known on T Tauri stars (2-3 days at minimum), but comparable to the Keplerian rotation period of inner accretion disk at a distance of r similar to 5 R-circle dot (M/M-circle dot)(1.5) Assuming that the temperature decrease is due to radiative cooling, and the plasma geometry is a solar-like flare loop of an aspect ratio (= length/diameter) of 10, we estimate that the plasma loop length is about 10 Ro. Possible origin for the quasi-periodic flaring, magnetic activity produced in a star and inner disk interacting region, is briefly discussed. (C) 2000 COSPAR. Published by Elsevier Science Ltd.

    Web of Science

    researchmap

  • Hard X-ray detection from the core of the Monoceros R2 star forming region

    K Hamaguchi, Y Tsuboi, K Koyama

    BROAD BAND X-RAY SPECTRA OF COSMIC SOURCES   25 ( 3-4 )   531 - 534   2000年

     詳細を見る

    記述言語:英語   出版者・発行元:PERGAMON PRESS LTD  

    We report on the hard X-ray detection from the core of the Monoceros R2 giant molecular cloud. The temperature is extremely high of about 5.5 keV in quiescent state. The strongest source among hard sources is associated with molecular core and suffered deep absorption. A hard X-ray flare near the core is also observed. The temperature is also extremely high. Strong Ca and Fe lines are observed in flare spectrum, and the energies are significantly lower than those of usual plasma model. The flare spectrum show some differences from those of low-mass young stars. It might be evidence of the X-rays from a high-mass protostar. (C) 2000 COSPAR. Published by Elsevier Science Ltd.

    Web of Science

    researchmap

  • チャンドラ衛星によるOMC 2-3領域のX線観測

    2000年度春季天文学会予稿集   2000年

     詳細を見る

  • オリオン ネビュラ クラスターのチャンドラX線観

    2000年度春季天文学会予稿集   2000年

     詳細を見る

  • X-ray spectral study of the most massive HII region NGC3603

    Abstract of the High-mass Star Formation: An Origin in Clusters?   84   2000年

     詳細を見る

  • X-ray emission from high-mass pre-main-sequence stars

    Abstract of the High-mass Star Formation: An Origin in Clusters?   57   2000年

     詳細を見る

  • Chandra衛星によるRhoOph星形成領域のX線観測

    2000年度秋季天文学会予稿集   2000年

     詳細を見る

  • Discovery of Hard X-rays from Class 0 candidates in the Orion Molecular Cloud 2/3 region with Chandra

    Bulletin of the American Astronomical Society   32 ( 3 )   1256   2000年

     詳細を見る

  • Some Data Analysis Technique for Chandra ACIS

    Bulletin of the American Astronomical Society   32 ( 3 )   1227   2000年

     詳細を見る

  • Chandra Deep Observation of the rho Ophiuchi Dark Cloud

    Bulletin of the American Astronomical Society   32 ( 3 )   1256   2000年

     詳細を見る

  • X-ray Emitting Class 0 Sources の近赤外詳細観測

    2001年度春季天文学会予稿集   2000年

     詳細を見る

  • Chandra衛星によるRhoOph星形成領域のX線観測II-X線フレアの詳細解析

    2001年度春季天文学会予稿集   2000年

     詳細を見る

  • Chandra/ACIS Observations of Protostars

    Bulletin of the American Astronomical Society   32 ( 4 )   1597   2000年

     詳細を見る

  • Chandra/ACIS Spectra of the 30 Doradus Star Forming Region

    Bulletin of the American Astronomical Society   32 ( 4 )   1594   2000年

     詳細を見る

  • Quasi-periodic X-ray flares on protostar YLW15

    Y Tsuboi, N Grosso, K Imanishi, K Koyama, T Montmerle

    BROAD BAND X-RAY SPECTRA OF COSMIC SOURCES   25 ( 3-4 )   535 - 538   2000年

     詳細を見る

    記述言語:英語   出版者・発行元:PERGAMON PRESS LTD  

    We detected three intermittent X-ray flares from a protostar YLSY15. Each flare occurred every similar to 20 hours, and showed an exponential decay of time constant 30-60 ks. The time-sliced X-ray spectra are all explained by a thin thermal plasma emission. The plasma temperature shows a fast-rise and a slow-decay for each flare, while the emission measure of the plasma increases only at the beginning of the first flare and is almost constant during the second and third hares. Thus the X-rays are attributable to a single plasma produced by the first large flare, then the plasma is re-heated quasi-periodically. The re-heating interval is significantly shorter than the spin periods known on T Tauri stars (2-3 days at minimum), but comparable to the Keplerian rotation period of inner accretion disk at a distance of r similar to 5 R-circle dot (M/M-circle dot)(1.5) Assuming that the temperature decrease is due to radiative cooling, and the plasma geometry is a solar-like flare loop of an aspect ratio (= length/diameter) of 10, we estimate that the plasma loop length is about 10 Ro. Possible origin for the quasi-periodic flaring, magnetic activity produced in a star and inner disk interacting region, is briefly discussed. (C) 2000 COSPAR. Published by Elsevier Science Ltd.

    Web of Science

    researchmap

  • Eta Carinae

    Corcoran, M.F

    IAU Circ.   ( 7177 )   2   1999年5月

     詳細を見る

    記述言語:英語   掲載種別:記事・総説・解説・論説等(その他)   出版者・発行元:Central Bureau for Astronomical telegrams  

    researchmap

  • Eta Carinae

    Corcoran, M.F

    IAU Circ.   ( 7177 )   2   1999年5月

     詳細を見る

    記述言語:英語   掲載種別:記事・総説・解説・論説等(その他)   出版者・発行元:Central Bureau for Astronomical telegrams  

    researchmap

  • Hard X-Ray Activities in Yound Stellar Objects

    Y.Tsuboi, K.Koyama

    Proc. of Star Formation 1999   187 - 188   1999年4月

     詳細を見る

    記述言語:英語   出版者・発行元:野辺山電波観測所  

    researchmap

  • Hard X-rays from Giant Molecular Cloud Core

    K.Hamaguchi, Y.Tsuboi, K.Koyama

    Proc. of the Japanese-German Workshop on high energy astrophysics   52 - 55   1999年4月

     詳細を見る

    記述言語:英語   出版者・発行元:MAX-Planck 研究所  

    researchmap

  • X-ray Study of Class I Protostars with ASCA

    Y.Tsuboi, K.Koyama

    Proc. of the Japanese-German Workshop on high energy astrophysics   3 - 5   1999年4月

     詳細を見る

    記述言語:英語   出版者・発行元:Max-Planck 研究所  

    researchmap

  • Quasi-Periodic X-Ray Flares from the Class I Protostar YLW15

    K.Imanishi, Y.Tsuboi, K.Koyama, N.Grosso, T.Montmerle

    Proc. of Star Formation 1999   312 - 313   1999年4月

     詳細を見る

    記述言語:英語   出版者・発行元:野辺山電波観測所  

    researchmap

  • Hard X-Ray Activities in Yound Stellar Objects

    Y.Tsuboi, K.Koyama

    Proc. of Star Formation 1999   187 - 188   1999年4月

     詳細を見る

    記述言語:英語   出版者・発行元:野辺山電波観測所  

    researchmap

  • Hard X-rays from Giant Molecular Cloud Core

    K.Hamaguchi, Y.Tsuboi, K.Koyama

    Proc. of the Japanese-German Workshop on high energy astrophysics   52 - 55   1999年4月

     詳細を見る

    記述言語:英語   出版者・発行元:MAX-Planck 研究所  

    researchmap

  • X-ray Study of Class I Protostars with ASCA

    Y.Tsuboi, K.Koyama

    Proc. of the Japanese-German Workshop on high energy astrophysics   3 - 5   1999年4月

     詳細を見る

    記述言語:英語   出版者・発行元:Max-Planck 研究所  

    researchmap

  • Quasi-Periodic X-Ray Flares from the Class I Protostar YLW15

    K.Imanishi, Y.Tsuboi, K.Koyama, N.Grosso, T.Montmerle

    Proc. of Star Formation 1999   312 - 313   1999年4月

     詳細を見る

    記述言語:英語   出版者・発行元:野辺山電波観測所  

    researchmap

  • X-Ray Study of the Bright W-R Star HD 93162 with Chandra

    Bulletin of the American Astronomical Society   31 ( 5 )   1541   1999年

     詳細を見る

  • ASCA Spectra of the Central Star of the Orion Nebula: a Magnetic O Star

    Bulletin of the American Astronomical Society   32 ( 2 )   705   1999年

     詳細を見る

  • Magnetic activities in Young Stellar Objects

    Y. Tsuboi, K. Hamaguchi, K. Koyama, S. Yamauchi

    Astronomische Nachrichten   320 ( 4-5 )   175 - 176   1999年

     詳細を見る

    記述言語:英語   出版者・発行元:Wiley-VCH Verlag  

    With ASCA, we detected hard X-rays from low-mass and high-mass Young Stellar Objects (YSOs), deeply embedded in dense molecular cloud cores. The X-rays from YSOs possessed line emissions from highly ionized ions of heavy elements, and were well fitted with thin-thermal plasma model. Some of them exhibited time valiabilities like solar flares, while their luminosities were at least 3-5 orders of magnitude larger than those from the Sun. These results support a scenario that stars in very young stage always emit magnetic-powered X-rays independently of the mass.

    DOI: 10.1002/1521-3994(199908)320:4/5<175::AID-ASNA175>3.0.CO;2-O

    Scopus

    researchmap

  • Chandra ACIS observation of the Orion Nebula Cluster

    Bulletin of the American Astronomical Society   31 ( 5 )   1491   1999年

     詳細を見る

  • Chandra/ACIS Observations of 30 Doradus

    Bulletin of the American Astronomical Society   31 ( 5 )   1453   1999年

     詳細を見る

  • X-ray activities in a Young Open Cluster: Chandra Observations of NGC2516

    Bulletin of the American Astronomical Society   31 ( 5 )   1442   1999年

     詳細を見る

  • X-Ray Study of the Bright W-R Star HD 93162 with Chandra

    Bulletin of the American Astronomical Society   31 ( 5 )   1541   1999年

     詳細を見る

  • ASCA Spectra of the Central Star of the Orion Nebula: a Magnetic O Star

    Bulletin of the American Astronomical Society   32 ( 2 )   705   1999年

     詳細を見る

  • Magnetic activities in Young Stellar Objects

    Y Tsuboi, K Hamaguchi, K Koyama, S Yamauchi

    ASTRONOMISCHE NACHRICHTEN   320 ( 4-5 )   175 - 176   1999年

     詳細を見る

    記述言語:英語   出版者・発行元:WILEY-V C H VERLAG GMBH  

    With ASCA, we detected hard X-rays from low-mass and high-mass Young Stellar Objects (YSOs), deeply embedded in dense molecular cloud cores. The X-rays from YSOs possessed line emissions from highly ionized ions of heavy elements, and were well fitted with thin-thermal plasma model. Some of them exhibited time valiabilities like solar flares, while their luminosities were at least 3-5 orders of magnitude larger than those from the Sun. These results support a scenario that stars in very young stage always emit magnetic-powered X-rays independently of the mass.

    Web of Science

    researchmap

  • Chandra ACIS observation of the Orion Nebula Cluster

    Bulletin of the American Astronomical Society   31 ( 5 )   1491   1999年

     詳細を見る

  • Chandra/ACIS Observations of 30 Doradus

    Bulletin of the American Astronomical Society   31 ( 5 )   1453   1999年

     詳細を見る

  • X-ray activities in a Young Open Cluster: Chandra Observations of NGC2516

    Bulletin of the American Astronomical Society   31 ( 5 )   1442   1999年

     詳細を見る

  • ASCA detection of a superhot 100 million K X-ray flare on the weak-lined T Tauri star V773 Tauri

    Y Tsuboi, K Koyama, H Murakami, M Hayashi, S Skinner, S Ueno

    ASTROPHYSICAL JOURNAL   503 ( 2 )   894 - 901   1998年8月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We present results of a approximate to 40 ks ASCA observation of the active weak-lined T Tauri star V773 Tau (HD 283447) and the surrounding Barnard 209 dark cloud, obtained in 1995 February. During this observation, V773 Tau exhibited a dramatic X-ray flare, with the X-ray count rate increasing rapidly by a factor of similar to 20, then decreasing exponentially with an e-folding timescale of approximate to 2.3 hr. The peak flare luminosity was at least similar to 10(33) ergs s(-1) (0.7-10 keV; distance = 150 pc), which is among the highest X-ray luminosities observed to date for T Tauri stars. The total energy release was similar to 10(37) ergs. However, the most spectacular aspect of this hare was its temperature, which reached a maximum value of at least 100 million K. Spectral fits near flare maximum give a temperature of similar to 10 keV, which slowly declined to a value similar to 6 keV at the end of the observation. These temperature measurements are based on high signal-to-noise ratio spectra, and provide the first unambiguous evidence for superhot flaring plasma at temperatures of similar to 10(8) K in T Tauri stars. A simple cooling-loop model gives electron densities that are similar to those of solar flares, but requires loop sizes that are comparable to or larger than the star itself. The flare showed other interesting behavior, including a high (and possibly variable) absorption column density, N-H = 4 x 10(22) cm(-2), and an apparent increase in the global metal abundance during the flare.

    DOI: 10.1086/306024

    Web of Science

    researchmap

  • ASCA detection of a superhot 100 million K X-ray flare on the weak-lined T Tauri star V773 Tauri

    Y Tsuboi, K Koyama, H Murakami, M Hayashi, S Skinner, S Ueno

    ASTROPHYSICAL JOURNAL   503 ( 2 )   894 - 901   1998年8月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We present results of a approximate to 40 ks ASCA observation of the active weak-lined T Tauri star V773 Tau (HD 283447) and the surrounding Barnard 209 dark cloud, obtained in 1995 February. During this observation, V773 Tau exhibited a dramatic X-ray flare, with the X-ray count rate increasing rapidly by a factor of similar to 20, then decreasing exponentially with an e-folding timescale of approximate to 2.3 hr. The peak flare luminosity was at least similar to 10(33) ergs s(-1) (0.7-10 keV; distance = 150 pc), which is among the highest X-ray luminosities observed to date for T Tauri stars. The total energy release was similar to 10(37) ergs. However, the most spectacular aspect of this hare was its temperature, which reached a maximum value of at least 100 million K. Spectral fits near flare maximum give a temperature of similar to 10 keV, which slowly declined to a value similar to 6 keV at the end of the observation. These temperature measurements are based on high signal-to-noise ratio spectra, and provide the first unambiguous evidence for superhot flaring plasma at temperatures of similar to 10(8) K in T Tauri stars. A simple cooling-loop model gives electron densities that are similar to those of solar flares, but requires loop sizes that are comparable to or larger than the star itself. The flare showed other interesting behavior, including a high (and possibly variable) absorption column density, N-H = 4 x 10(22) cm(-2), and an apparent increase in the global metal abundance during the flare.

    DOI: 10.1086/306024

    Web of Science

    researchmap

  • X-ray Emission from the Orion Nebula Region 査読

    M.Gagne, Y.Tsuboi

    Proc. of the ASP Conf. Series The Orion Complex Revisited   1998年4月

     詳細を見る

    記述言語:英語   出版者・発行元:The Astronomical Society of the Pacific  

    researchmap

  • X-ray Emission from the Orion Nebula Region 査読

    M.Gagne, Y.Tsuboi

    Proc. of the ASP Conf. Series The Orion Complex Revisited   1998年4月

     詳細を見る

    記述言語:英語   出版者・発行元:The Astronomical Society of the Pacific  

    researchmap

  • The ASCA X-ray spectrum of eta Carinae

    MF Corcoran, R Petre, JH Swank, SA Drake, K Koyama, Y Tsuboi, R Viotti, A Damineli, K Davidson, K Ishibashi, S White, D Currie

    ASTROPHYSICAL JOURNAL   494 ( 1 )   381 - 395   1998年2月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We have obtained high signal-to-noise ratio 0.5-10 keV band X-ray spectra of the peculiar, extremely luminous star eta Carinae with the Advanced Satellite for Cosmology and Astrophysics (ASCA) X-ray observatory during Cycle 4 observations in mid-1996. These data comprise the best X-ray spectra to date of the cool source (kT similar to 0.3 keV) surrounding the homunculus and of the hot source (kT similar to 5 keV) associated with eta Car itself. We identify line emission from ions of N, Mg, Si, and S and numerous strong transitions of Fe in a variety of ionization stages, including the first clear identification of a fluorescent Fe line produced by photoionization of cool material by the X-ray continuum from the hot source. The line strengths are consistent with thermal equilibrium models, though abundances of some important elements are nonsolar. Our analysis suggests that Fe is slightly underabundant and S and Si somewhat overabundant. Most importantly, we confirm the high N enrichment derived by Tsuboi et al. from their analysis of a shorter ASCA observation obtained during the performance verification (PV) phase in 1993 August. The O/N abundance ratio derived from the ASCA spectra is consistent with an upper limit from optical/UV spectral analysis (Davidson et al.) and with predictions of evolutionary models for extremely massive stars. Comparison of the Cycle 4 and PV-phase spectra shows that the X-ray luminosity increased by similar to 50% during this 3 year interval. Using the ASCA spectral model as a template, we reevaluate the spectrum of II Car obtained by the Rontgen Satelite (ROSAT) in late 1992 and construct an X-ray light curve for the 1992.4-1996.6 interval. We present spectra from the Intel national Ultraviolet Explorer (IUE) satellite obtained at nearly the same time as the Cycle 4 ASCA spectra and show that the observed X-ray variability is reflected in changes of some important UV spectral features. Our data suggest that the X-ray emission and state of the stellar wind are intimately connected, though the exact mechanism of coupling is not known. We suggest two alternatives: an underlying photospheric change of undetermined origin in eta Car itself, or a collision between a dense stellar wind from eta Car and the wind or photosphere of a companion.

    DOI: 10.1086/305190

    Web of Science

    researchmap

  • The ASCA X-ray spectrum of eta Carinae

    MF Corcoran, R Petre, JH Swank, SA Drake, K Koyama, Y Tsuboi, R Viotti, A Damineli, K Davidson, K Ishibashi, S White, D Currie

    ASTROPHYSICAL JOURNAL   494 ( 1 )   381 - 395   1998年2月

     詳細を見る

    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We have obtained high signal-to-noise ratio 0.5-10 keV band X-ray spectra of the peculiar, extremely luminous star eta Carinae with the Advanced Satellite for Cosmology and Astrophysics (ASCA) X-ray observatory during Cycle 4 observations in mid-1996. These data comprise the best X-ray spectra to date of the cool source (kT similar to 0.3 keV) surrounding the homunculus and of the hot source (kT similar to 5 keV) associated with eta Car itself. We identify line emission from ions of N, Mg, Si, and S and numerous strong transitions of Fe in a variety of ionization stages, including the first clear identification of a fluorescent Fe line produced by photoionization of cool material by the X-ray continuum from the hot source. The line strengths are consistent with thermal equilibrium models, though abundances of some important elements are nonsolar. Our analysis suggests that Fe is slightly underabundant and S and Si somewhat overabundant. Most importantly, we confirm the high N enrichment derived by Tsuboi et al. from their analysis of a shorter ASCA observation obtained during the performance verification (PV) phase in 1993 August. The O/N abundance ratio derived from the ASCA spectra is consistent with an upper limit from optical/UV spectral analysis (Davidson et al.) and with predictions of evolutionary models for extremely massive stars. Comparison of the Cycle 4 and PV-phase spectra shows that the X-ray luminosity increased by similar to 50% during this 3 year interval. Using the ASCA spectral model as a template, we reevaluate the spectrum of II Car obtained by the Rontgen Satelite (ROSAT) in late 1992 and construct an X-ray light curve for the 1992.4-1996.6 interval. We present spectra from the Intel national Ultraviolet Explorer (IUE) satellite obtained at nearly the same time as the Cycle 4 ASCA spectra and show that the observed X-ray variability is reflected in changes of some important UV spectral features. Our data suggest that the X-ray emission and state of the stellar wind are intimately connected, though the exact mechanism of coupling is not known. We suggest two alternatives: an underlying photospheric change of undetermined origin in eta Car itself, or a collision between a dense stellar wind from eta Car and the wind or photosphere of a companion.

    DOI: 10.1086/305190

    Web of Science

    researchmap

  • ASCA observation of NGC1333 star forming region

    M Itoh, H Fukunaga, K Koyama, Y Tsuboi, S Yamauchi, N Kobayashi, M Hayashi, S Ueno

    HOT UNIVERSE   ( 188 )   228 - 229   1998年

     詳細を見る

    記述言語:英語   出版者・発行元:KLUWER ACADEMIC PUBL  

    Web of Science

    researchmap

  • ASCA observations of Class I protostars in the Rho Oph dark cloud

    Y Tsuboi, K Koyama, Y Kamata, S Yamauchi

    HOT UNIVERSE   ( 188 )   236 - 237   1998年

     詳細を見る

    記述言語:英語   出版者・発行元:KLUWER ACADEMIC PUBL  

    Web of Science

    researchmap

  • ASCA observation of NGC1333 star forming region

    M Itoh, H Fukunaga, K Koyama, Y Tsuboi, S Yamauchi, N Kobayashi, M Hayashi, S Ueno

    HOT UNIVERSE   ( 188 )   228 - 229   1998年

     詳細を見る

    記述言語:英語   出版者・発行元:KLUWER ACADEMIC PUBL  

    Web of Science

    researchmap

  • ASCA observations of Class I protostars in the Rho Oph dark cloud

    Y Tsuboi, K Koyama, Y Kamata, S Yamauchi

    HOT UNIVERSE   ( 188 )   236 - 237   1998年

     詳細を見る

    記述言語:英語   出版者・発行元:KLUWER ACADEMIC PUBL  

    Web of Science

    researchmap

  • ASCA Observations of Embedded Sources in Dark Clouds 査読

    K.Koyama, K.Hamaguchi, H.Murakami, Y.Tsuboi

    Memorie della Societa Astromia Italiana   68   1033 - 1037   1997年12月

     詳細を見る

    記述言語:英語   出版者・発行元:イタリア天文学会  

    researchmap

  • ASCA Observations of X-Rays from YSOs 査読

    Y.Tsuboi, ABC

    Memorie della Societa Astronomia Italiana   68   1039 - 1042   1997年12月

     詳細を見る

    記述言語:英語   出版者・発行元:イタリア天文学会  

    researchmap

  • ASCA Observations of Embedded Sources in Dark Clouds 査読

    K.Koyama, K.Hamaguchi, H.Murakami, Y.Tsuboi

    Memorie della Societa Astromia Italiana   68   1033 - 1037   1997年12月

     詳細を見る

    記述言語:英語   出版者・発行元:イタリア天文学会  

    researchmap

  • ASCA Observations of X-Rays from YSOs 査読

    Y.Tsuboi, ABC

    Memorie della Societa Astronomia Italiana   68   1039 - 1042   1997年12月

     詳細を見る

    記述言語:英語   出版者・発行元:イタリア天文学会  

    researchmap

  • Molecular outflows from X-ray-emitting protostars in the rho Ophiuchi dark cloud

    Y Sekimoto, K Tatematsu, T Umemoto, K Koyama, Y Tsuboi, N Hirano, S Yamamoto

    ASTROPHYSICAL JOURNAL   489 ( 1 )   L63 - &   1997年11月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    We report CO (J = 2-1, J = 1-0) outflows from four X-ray-emitting protostars (EL29, IRS44, WL6, WL10) in the rho Ophiuchi cloud core which have been firmly identified with the X-ray satellite ASCA. The common feature of these outflows is that the blue and red lobes are largely overlapped, which indicates that the inclination angle between the outflow axis and line of sight is smaller than 30 degrees (nearly pole-on configuration). Taking account of the hard X-ray transparency (N-H similar to 10(23) cm(-2)) and the column density of a circumstellar disk (N-H&gt;10(24) cm(-2)), it is naturally understood that hard X-rays emitted near the surface of protostars or the inner part of the disk are observed in the nearly pole-on configuration. The outflow detection rate (4/5) in the present observations shows that a low-mass protostar emits X-rays even in the outflow phase of early stellar evolution.

    Web of Science

    researchmap

  • Molecular outflows from X-ray-emitting protostars in the rho Ophiuchi dark cloud

    Y Sekimoto, K Tatematsu, T Umemoto, K Koyama, Y Tsuboi, N Hirano, S Yamamoto

    ASTROPHYSICAL JOURNAL   489 ( 1 )   L63 - &   1997年11月

     詳細を見る

    記述言語:英語   出版者・発行元:UNIV CHICAGO PRESS  

    We report CO (J = 2-1, J = 1-0) outflows from four X-ray-emitting protostars (EL29, IRS44, WL6, WL10) in the rho Ophiuchi cloud core which have been firmly identified with the X-ray satellite ASCA. The common feature of these outflows is that the blue and red lobes are largely overlapped, which indicates that the inclination angle between the outflow axis and line of sight is smaller than 30 degrees (nearly pole-on configuration). Taking account of the hard X-ray transparency (N-H similar to 10(23) cm(-2)) and the column density of a circumstellar disk (N-H&gt;10(24) cm(-2)), it is naturally understood that hard X-rays emitted near the surface of protostars or the inner part of the disk are observed in the nearly pole-on configuration. The outflow detection rate (4/5) in the present observations shows that a low-mass protostar emits X-rays even in the outflow phase of early stellar evolution.

    Web of Science

    researchmap

  • X-ray analysis of the rho Ophiuchi dark cloud with ASCA: Source identification, X-ray spectra, and temporal variability

    Y Kamata, K Koyama, Y Tsuboi, S Yamauchi

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   49 ( 4 )   461 - 470   1997年8月

     詳細を見る

    記述言語:英語   出版者・発行元:OXFORD UNIV PRESS  

    This paper presents a comprehensive study with the Japanese X-ray astronomical satellite ASCA on X-rays from the main body of the rho Ophiuchi dark cloud. We have constructed separate X-ray images using 3 energy bands and 12 time-sliced data, and thereby detected 19 X-ray sources, doubling the previous ASCA results of II X-ray sources. Three of the sources are associated with class-I infrared sources, which precede the T Tauri phase. Half of the 19 sources were found to be time variable, and 5 flare-like events with an averaged energy of &gt; 3 x 10(35) erg were observed. With the analogy of solar flares, we estimated the flare loop height and plasma density to be 3 x 10(11) cm and 3 x 10(11) cm(-3), respectively. Among these sources, a flare from the class-I source EL 29 exhibited an order-of-magnitude larger absorption (N-H) than in quiescence states, which may indicate the exsistence of a dense protostellar disk.

    DOI: 10.1093/pasj/49.4.461

    Web of Science

    researchmap

  • X-ray analysis of the rho Ophiuchi dark cloud with ASCA: Source identification, X-ray spectra, and temporal variability

    Y Kamata, K Koyama, Y Tsuboi, S Yamauchi

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   49 ( 4 )   461 - 470   1997年8月

     詳細を見る

    記述言語:英語   出版者・発行元:OXFORD UNIV PRESS  

    This paper presents a comprehensive study with the Japanese X-ray astronomical satellite ASCA on X-rays from the main body of the rho Ophiuchi dark cloud. We have constructed separate X-ray images using 3 energy bands and 12 time-sliced data, and thereby detected 19 X-ray sources, doubling the previous ASCA results of II X-ray sources. Three of the sources are associated with class-I infrared sources, which precede the T Tauri phase. Half of the 19 sources were found to be time variable, and 5 flare-like events with an averaged energy of &gt; 3 x 10(35) erg were observed. With the analogy of solar flares, we estimated the flare loop height and plasma density to be 3 x 10(11) cm and 3 x 10(11) cm(-3), respectively. Among these sources, a flare from the class-I source EL 29 exhibited an order-of-magnitude larger absorption (N-H) than in quiescence states, which may indicate the exsistence of a dense protostellar disk.

    DOI: 10.1093/pasj/49.4.461

    Web of Science

    researchmap

  • X-Rays from Young Stars - a Giant X-Ray Flare from V773 Tan -

    Y.Tsuboi, S.Ueno, K.Koyama

    Proc. of the X-Ray Imaging and Spectroscopy of Hot Plasmas   583 - 584   1997年4月

     詳細を見る

    記述言語:英語   出版者・発行元:Universal Academy 出版社  

    researchmap

  • X-Rays from Young Stars - a Giant X-Ray Flare from V773 Tan -

    Y.Tsuboi, S.Ueno, K.Koyama

    Proc. of the X-Ray Imaging and Spectroscopy of Hot Plasmas   583 - 584   1997年4月

     詳細を見る

    記述言語:英語   出版者・発行元:Universal Academy 出版社  

    researchmap

  • ASCA observations of Eta Carinae

    Y Tsuboi, K Koyama, M Sakano, R Petre

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   49 ( 1 )   85 - 92   1997年2月

     詳細を見る

    記述言語:英語   出版者・発行元:OXFORD UNIV PRESS  

    We present ASCA results on the peculiar star eta Car in the center of the Carina Nebula. The X-ray emission from eta Car was found to be attributable to two thermal components: the high-temperature component (kT similar to 5 keV) is consistent with a point source, and is highly absorbed, while the low-temperature plasma (kT similar to 0.7 keV) is extended, and shows no significant circumstellar absorption. We found a line-like structure around 0.5 keV, which is probably due to the Ly alpha line of nitrogen. Using a variable-abundance coronal plasma model, we found that the relative abundance of nitrogen to oxygen is extremely large in comparison with the solar value. This may be the first X-ray evidence of the enrichment of CNO-processed material in an evolved massive star.

    DOI: 10.1093/pasj/49.1.85

    Web of Science

    researchmap

  • ASCA observations of Eta Carinae

    Y Tsuboi, K Koyama, M Sakano, R Petre

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   49 ( 1 )   85 - 92   1997年2月

     詳細を見る

    記述言語:英語   出版者・発行元:OXFORD UNIV PRESS  

    We present ASCA results on the peculiar star eta Car in the center of the Carina Nebula. The X-ray emission from eta Car was found to be attributable to two thermal components: the high-temperature component (kT similar to 5 keV) is consistent with a point source, and is highly absorbed, while the low-temperature plasma (kT similar to 0.7 keV) is extended, and shows no significant circumstellar absorption. We found a line-like structure around 0.5 keV, which is probably due to the Ly alpha line of nitrogen. Using a variable-abundance coronal plasma model, we found that the relative abundance of nitrogen to oxygen is extremely large in comparison with the solar value. This may be the first X-ray evidence of the enrichment of CNO-processed material in an evolved massive star.

    DOI: 10.1093/pasj/49.1.85

    Web of Science

    researchmap

  • Skylight「X線でさぐる原始星」

    坪井陽子, 小山勝二

    天文月報   90 ( 1 )   8   1997年1月

     詳細を見る

    記述言語:日本語   掲載種別:記事・総説・解説・論説等(その他)   出版者・発行元:日本天文学会  

    researchmap

  • rho-Oph分子雲のX線描像

    LMSA Science Workshop『LMSA計画と高エネルギー天文学』収録   1997年

     詳細を見る

  • X-ray Spectral Variability of Eta Carinae

    Bulletin of the American Astronomical Society   29 ( 5 )   1261   1997年

     詳細を見る

  • Hard X-ray emissions from star forming regions

    Y Tsuboi, K Koyama, S Ueno

    STAR FORMATION NEAR AND FAR - SEVENTH ASTROPHYSICS CONFERENCE   393 ( 393 )   175 - 178   1997年

     詳細を見る

    記述言語:英語   出版者・発行元:AIP PRESS  

    ASCA is the first satellite which has an imaging capability in high energies up to 10 keV, hence can peer deeply into the molecular cloud where protostar candidates may reside. We have carried out a systematic survey of hard X-rays from the core of molecular clouds, and discovered hard X-rays from protostar candidates (Class I objects) in the core of Rho Oph dark cloud. Two of them showed clear time variability; one (EL29) is flare-like and the other (WL6) is sinusoidal flux variation.
    On the other hand, in Taurus dark cloud, we have detected a giant flare of a weak-lined TTS, V773 Tau in hard X-ray band. The plasma temperature was extremely high, about 8 keV, at the maximum flux, then it decreased as the flux decreased. The decay time and estimated electron density were found to be comparable to those of the sun, but the geometrical flare size was equal or even larger than the stellar size. The absorption column during the flare was large, about 3.6 x 10(22) H cm(-3), and it makes impossible to detect the flare in soft X-ray band. Interestingly, in the decay phase, we found the apparent change of the metal abundance.

    Web of Science

    researchmap

  • X-ray Spectral Variability of Eta Carinae

    Bulletin of the American Astronomical Society   29 ( 5 )   1261   1997年

     詳細を見る

  • Hard X-ray emissions from star forming regions

    Y Tsuboi, K Koyama, S Ueno

    STAR FORMATION NEAR AND FAR - SEVENTH ASTROPHYSICS CONFERENCE   393 ( 393 )   175 - 178   1997年

     詳細を見る

    記述言語:英語   出版者・発行元:AIP PRESS  

    ASCA is the first satellite which has an imaging capability in high energies up to 10 keV, hence can peer deeply into the molecular cloud where protostar candidates may reside. We have carried out a systematic survey of hard X-rays from the core of molecular clouds, and discovered hard X-rays from protostar candidates (Class I objects) in the core of Rho Oph dark cloud. Two of them showed clear time variability; one (EL29) is flare-like and the other (WL6) is sinusoidal flux variation.
    On the other hand, in Taurus dark cloud, we have detected a giant flare of a weak-lined TTS, V773 Tau in hard X-ray band. The plasma temperature was extremely high, about 8 keV, at the maximum flux, then it decreased as the flux decreased. The decay time and estimated electron density were found to be comparable to those of the sun, but the geometrical flare size was equal or even larger than the stellar size. The absorption column during the flare was large, about 3.6 x 10(22) H cm(-3), and it makes impossible to detect the flare in soft X-ray band. Interestingly, in the decay phase, we found the apparent change of the metal abundance.

    Web of Science

    researchmap

  • 原始星からのX線~rho Oph分子雲~

    ラインX線・ガンマ線による天体物理(V)収録   146 - 150   1997年

     詳細を見る

  • CCD Cal装置の開発装置(I)

    ラインX線・ガンマ線による天体物理(V)収録   167 - 169   1997年

     詳細を見る

  • 衛星搭載用X線CCDの評価システムの開発

    1997年春季物理学会予稿集   1997年

     詳細を見る

  • X-Ray Spectra from Star Forming Regions

    K.Koyama, Y.Tsuboi, S.Ueno

    Proc. of the UV and X-Ray Spectroscopy of Astrophysical and Laboratory Plasmas   105 - 110   1996年4月

     詳細を見る

    記述言語:英語   出版者・発行元:Universal Academy 出版社  

    researchmap

  • Hard X-Ray Emissions from Protostar Candidates

    K.Koyama, Y.Tsuboi, S.Ueno

    Proc. of the Magetodynamic phenomena in the solar atmosphere - Prototypes of Stellar Magnetic Activity   243- - 243   1996年4月

     詳細を見る

    記述言語:英語   出版者・発行元:Kluwer Academic 出版社  

    researchmap

  • Spatial and Spectral Structure of η Carinae

    Y.Tsuboi, K.Koyama

    Proc. of the UV and X-ray Spectroscopy of Astrophysical and Laboratory Plasmas   271 - 274   1996年4月

     詳細を見る

    記述言語:英語   出版者・発行元:Universal Academy 出版社  

    researchmap

  • X-Ray Spectra from Star Forming Regions

    K.Koyama, Y.Tsuboi, S.Ueno

    Proc. of the UV and X-Ray Spectroscopy of Astrophysical and Laboratory Plasmas   105 - 110   1996年4月

     詳細を見る

    記述言語:英語   出版者・発行元:Universal Academy 出版社  

    researchmap

  • Spatial and Spectral Structure of η Carinae

    Y.Tsuboi, K.Koyama

    Proc. of the UV and X-ray Spectroscopy of Astrophysical and Laboratory Plasmas   271 - 274   1996年4月

     詳細を見る

    記述言語:英語   出版者・発行元:Universal Academy 出版社  

    researchmap

  • Spectral and spatial structure of eta Carinae

    Y Tsuboi, K Koyama, R Petre

    MAGNETODYNAMIC PHENOMENA IN THE SOLAR ATMOSPHERE   481 - 482   1996年

     詳細を見る

    記述言語:英語   出版者・発行元:KLUWER ACADEMIC PUBL  

    Web of Science

    researchmap

  • Hard X-ray emissions from protostar candidate

    K Koyama, Y Tsuboi, S Ueno

    MAGNETODYNAMIC PHENOMENA IN THE SOLAR ATMOSPHERE   243 - 246   1996年

     詳細を見る

    記述言語:英語   出版者・発行元:KLUWER ACADEMIC PUBL  

    Web of Science

    researchmap

  • V773 TauからのX線フレア観測

    1996年度日本天文学会春季年会予稿集   1996年

     詳細を見る

  • ASCAによる星生成領域の観測

    1996年科学衛星・宇宙観測シンポジウム収録   1996年

     詳細を見る

  • Spectral and spatial structure of eta Carinae

    Y Tsuboi, K Koyama, R Petre

    MAGNETODYNAMIC PHENOMENA IN THE SOLAR ATMOSPHERE   481 - 482   1996年

     詳細を見る

    記述言語:英語   出版者・発行元:KLUWER ACADEMIC PUBL  

    Web of Science

    researchmap

  • 前主系列星巨大フレアのプラズマ診断~V773 TauのX線フレア~

    1996年度秋季天文学会予稿集   1996年

     詳細を見る

  • 原始星のX線と双極分子流構造

    重点領域"高エネルギー天体”葉山研究会収録   1996年

     詳細を見る

  • ASCA X-RAY OBSERVATIONS OF THE WOLF-RAYET STARS HD-193793 AND HD-93162

    S SKINNER, F NAGASE, K KOYAMA, Y MAEDA, Y TSUBOI

    WOLF-RAYET STARS: BINARIES, COLLIDING WINDS, EVOLUTION   ( 163 )   471 - 475   1995年

     詳細を見る

    記述言語:英語   出版者・発行元:KLUWER ACADEMIC PUBL  

    The Japan-U.S. satellite ASCA was launched in February 1993 and provides a new capability to obtain high-resolution X-ray spectra of Wolf-Rayet stars in the 0.5 - 10 keV band. We present spectra of the wide binary HD 193793 (WC7+O4-5) obtained three months after periastron with the WC7 star in front, and of the WN7 star HD 93162 in Carina. The spectrum of HD 193793 is heavily absorbed below 2 keV by the WC7 wind and shows a prominent emission line from He-like iron at 6.7 keV. Acceptable fits were obtained using a Raymond-Smith model with kT approximate to 3 keV and non-solar abundances. In contrast, the spectrum of HD 93162 is softer and shows very little emission above approximate to 2 keV. The relatively low signal-to-noise precludes emission line analysis, and an acceptable spectral fit was obtained using a simple Bremsstrahlung model with kT approximate to 1.6 keV. No significant variability was detected in the X-ray light-curves of either star.

    Web of Science

    researchmap

  • ASCA X-RAY OBSERVATIONS OF THE WOLF-RAYET STARS HD-193793 AND HD-93162

    S SKINNER, F NAGASE, K KOYAMA, Y MAEDA, Y TSUBOI

    WOLF-RAYET STARS: BINARIES, COLLIDING WINDS, EVOLUTION   ( 163 )   471 - 475   1995年

     詳細を見る

    記述言語:英語   出版者・発行元:KLUWER ACADEMIC PUBL  

    The Japan-U.S. satellite ASCA was launched in February 1993 and provides a new capability to obtain high-resolution X-ray spectra of Wolf-Rayet stars in the 0.5 - 10 keV band. We present spectra of the wide binary HD 193793 (WC7+O4-5) obtained three months after periastron with the WC7 star in front, and of the WN7 star HD 93162 in Carina. The spectrum of HD 193793 is heavily absorbed below 2 keV by the WC7 wind and shows a prominent emission line from He-like iron at 6.7 keV. Acceptable fits were obtained using a Raymond-Smith model with kT approximate to 3 keV and non-solar abundances. In contrast, the spectrum of HD 93162 is softer and shows very little emission above approximate to 2 keV. The relatively low signal-to-noise precludes emission line analysis, and an acceptable spectral fit was obtained using a simple Bremsstrahlung model with kT approximate to 1.6 keV. No significant variability was detected in the X-ray light-curves of either star.

    Web of Science

    researchmap

  • eta Carの空間及びスペクトル構造

    太陽および恒星の超高温、高エネルギー現象研究会収録   1995年

     詳細を見る

  • Spatial and Spectral structure of eta Car

    1995年度日本天文学会春季年会予稿集   1995年

     詳細を見る

  • NEW TRANSIENT-X-RAY SOURCE IN THE SCUTUM REGION DISCOVERED WITH ASCA

    S YAMAUCHI, T AOKI, K HAYASHIDA, H KANEDA, K KOYAMA, M SUGIZAKI, Y TANAKA, H TOMIDA, Y TSUBOI

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   47 ( 2 )   189 - 194   1995年

     詳細を見る

    記述言語:英語   出版者・発行元:ASTRONOMICAL SOC JAPAN  

    Using the ASCA satellite we have discovered a new transient X-ray source at the position of RA(2000)= 18(h)45(m)2(s), Dec(2000) = -4 degrees 33'31'' (uncertainty = 1'), designated as AX 1845.0-0433. The NH-corrected X-ray flux was similar to 3 x 10(-12) erg s(-1) cm(-2) in the 0.7-10 keV region at the beginning of the observation; the X-ray source then suddenly flared up to a level of about 1 x 10(-9) erg s(-1) cm(-2) in the 0.7-10 keV region after N-H-correction within less than a few hours. It exhibited flare-like activity on the minimum time scale of a few ten minutes; the activity lasted until the end of the observation. The X-ray spectra in the quiescent and flare states resemble those of binary X-ray pulsars. However, no coherent pulsation was found in the range from 125 ms to 4096 s.

    Web of Science

    researchmap

  • Spatial and Spectral structure of eta Car

    1995年度日本天文学会春季年会予稿集   1995年

     詳細を見る

  • Carina Nebulaに拡がるX線起源の考察

    原始惑星系円盤ワークショップ収録   1995年

     詳細を見る

  • NEW TRANSIENT-X-RAY SOURCE IN THE SCUTUM REGION DISCOVERED WITH ASCA

    S YAMAUCHI, T AOKI, K HAYASHIDA, H KANEDA, K KOYAMA, M SUGIZAKI, Y TANAKA, H TOMIDA, Y TSUBOI

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   47 ( 2 )   189 - 194   1995年

     詳細を見る

    記述言語:英語   出版者・発行元:ASTRONOMICAL SOC JAPAN  

    Using the ASCA satellite we have discovered a new transient X-ray source at the position of RA(2000)= 18(h)45(m)2(s), Dec(2000) = -4 degrees 33'31'' (uncertainty = 1'), designated as AX 1845.0-0433. The NH-corrected X-ray flux was similar to 3 x 10(-12) erg s(-1) cm(-2) in the 0.7-10 keV region at the beginning of the observation; the X-ray source then suddenly flared up to a level of about 1 x 10(-9) erg s(-1) cm(-2) in the 0.7-10 keV region after N-H-correction within less than a few hours. It exhibited flare-like activity on the minimum time scale of a few ten minutes; the activity lasted until the end of the observation. The X-ray spectra in the quiescent and flare states resemble those of binary X-ray pulsars. However, no coherent pulsation was found in the range from 125 ms to 4096 s.

    Web of Science

    researchmap

  • X線で探る恒星の生成過程~Herbig Ae/Be starの観測~

    重点領域研究「星間物質とその進化」大研究会収録   1995年

     詳細を見る

  • 硬X線による星生成領域の観測

    1995年日本天文学会秋季年会予稿集   1995年

     詳細を見る

  • 星生成領域からのX線放射~V773 Tauからの巨大X線フレア観測~

    ラインX線・ガンマ線による天体物理(IV)収録   170 - 174   1995年

     詳細を見る

  • ASCA Observation of η Car

    Y.Tsuboi, K.Koyama

    Proc. of the New Horizon of X-Ray Astronomy   403 - 404   1994年4月

     詳細を見る

    記述言語:英語   出版者・発行元:Universal Academy Press  

    researchmap

  • ASCA Observation of η Car

    Y.Tsuboi, K.Koyama

    Proc. of the New Horizon of X-Ray Astronomy   403 - 404   1994年4月

     詳細を見る

    記述言語:英語   出版者・発行元:Universal Academy Press  

    researchmap

  • X線放射と原始星の進化2;大質量星

    重点領域研究「星間物質とその進化」大研究会収録   1994年

     詳細を見る

  • eta Carの空間及びスペクトル構造

    ラインX線・ガンマ線による天体物理(III)収録   55 - 59   1994年

     詳細を見る

▼全件表示

講演・口頭発表等

  • 可視光測光;分光自動追観測システム PHAST による巨大恒星フレア観測

    甲原潤也, 坪井陽子, 浦部蒼太, 那波咲良, 根本登, 後藤絵美, 金子陽, 猶木皓太, 河合広樹, 岩切渉, 他 MAXI チーム

    日本天文学会2023年春季年会  2023年3月 

     詳細を見る

    開催年月日: 2023年3月    

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • M29a おひつじ座 UX 星で起こった巨大フレアのせいめい及び MAXI による同時観測

    那波咲良, 坪井陽子, 岩切渉, 浦部蒼太, 根本登, 甲原潤也, 前原裕之, 行方宏介, 野津湧太, 他 MAXI チーム

    日本天文学会2022年秋季年会  2022年9月 

     詳細を見る

    開催年月日: 2022年9月    

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • 恒星フレア自動観測のための中央大学 40cm 可視光望遠鏡

    甲原潤也, 坪井陽子, 岩切渉, 河合広樹, 浦部蒼太, 那波咲良, 根本登

    日本天文学会2022年春季年会  2022年3月 

     詳細を見る

    開催年月日: 2022年3月    

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • 湾曲 Si 結晶を用いたブラッグ反射型偏光計の分光性能評価 (2)

    井上諒大, 坪井陽子, 岩切渉, 中島七海, 前田良知

    日本天文学会2022年春季年会  2022年3月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • 多波長同時観測で迫るおひつじ座UX星で生じた巨大フレアの特徴 (2)

    北古賀智紀, 坪井陽子, 岩切渉, 河合広樹, 佐々木亮, 米倉覚則, 岳藤一宏, 新沼浩太郎, 元木業人, 藤 沢健太, 青木貴弘, 下条圭美, 梅本智文

    日本天文学会2022年春季年会  2022年3月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • 巨大フレア同時観測で得た軟X線とHα線のフレア減衰時間の相関

    河合広樹, 坪井陽子, 岩切渉, 佐々木亮, 前田良知, 菅原泰晴, AXA, ISAS, 勝田哲, 他 MAXI チーム

    日本天文学会2021年秋季年会  2021年9月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • TESSで観測したけんびきょう座AT星のフレア検出方法およびフレア発生頻度分布について

    岡本豊, 坪井陽子, 岩切渉, 佐々木亮, 河合広樹, 行方宏介, 野津湧太, 河合 誠之, 河原創, 他 MAXI チーム

    日本天文学会2021年秋季年会  2021年9月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • X-Rays from Class 0/I Protostars

    Y.Tsuboi

    Abstract of the Star Formation at High Angular Resolution, International Astronomical Union. Symposium no.221/IAU  2003年7月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • Chandra/ACIS Observations of the 30 Doradus Star-Forming Complex

    L.Townsley

    Abstract of the American Physical Society, April Meeting,アメリカ天文学会  2002年4月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • XMM-Newton EPIC Observations of OMC-2/3 region

    Y.Tsuboi, E.D.Feigelson, K.Koyama, M.Tsujimoto, J.Bally, B.Reipurth

    Bulletin of the American Astronomical Society,アメリカ天文学会  2001年12月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • Magnetic flaring in the young Sun and implications for solar nebula solids

    E.Feigelson, G.Garmire, Y.Tsuboi, S.Pravdp

    Abstract of the Two Years of Science with Chandra/CXC  2001年9月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • X-rays from the Brown Dwarf BD TWA-5B

    Y.Tsuboi, G.Chartas, E.Feigelson, G.Garmire, Y.Maeda, K.Mori, L.Townsley

    Abstract of the Two Years of Science with Chandra/CXC  2001年9月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • X-rays From A Protostellar Outflow: HH 2

    Pravdo.S

    Bulletin of the American Astronomical Society,アメリカ天文学会  2001年5月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • Chandra/ACIS Observations of Protostars

    Tsuboi.Y

    Bulletin of the American Astronomical Society,アメリカ天文学会  2000年12月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • Chandra/ACIS Spectra of the 30 Doradus Star Forming Region

    Townsley.L, ABC

    Bulletin of the American Astronomical Society,アメリカ天文学会  2000年12月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • Chandra衛星によるRhoOph星形成領域のX線観測

    今西健介, 濱口健二, 小山勝二, 坪井陽子

    2000年度秋季天文学会予稿集,日本天文学会  2000年10月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • Discovery of Hard X-rays from Class 0 candidates in the Orion Molecular Cloud 2/3 region with Chandra

    Tsuboi.Y, ABC

    Bulletin of the American Astronomical Society,アメリカ天文学会  2000年10月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • Some Data Analysis Technique for Chandra ACIS

    Feigelson, E.D

    Bulletin of the American Astronomical Society,アメリカ天文学会  2000年10月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • Chandra Deep Observation of the rho Ophiuchi Dark Cloud

    Tsuboi.Y, Hamaguchi.K, Imanishi.K, Koyama.K

    Bulletin of the American Astronomical Society,アメリカ天文学会  2000年10月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • X-ray Emitting Class 0 Sources の近赤外詳細観測

    辻本匡弘

    2001年度春季天文学会予稿集,日本天文学会  2000年10月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • Chandra衛星によるRhoOph星形成領域のX線観測II-X線フレアの詳細解析

    今西健介, 小山勝二, 坪井陽子

    2001年度春季天文学会予稿集,日本天文学会  2000年10月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • X-ray spectral study of the most massive HII region NGC3603

    Y.Tsuboi, Y.Maeda

    Abstract of the High-mass Star Formation: An Origin in Clusters?/Arcetri Observastory  2000年5月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • X-ray emission from high-mass pre-main-sequence stars

    K.Hamaguchi, H.Terada, A.Bamba, Y.Tsuboi, K.Koyama

    Abstract of the High-mass Star Formation: An Origin in Clusters?/Arcetri Observastory  2000年5月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • チャンドラ衛星によるOMC 2-3領域のX線観測

    Y.Tsuboi, ABC

    2000年度春季天文学会予稿集,日本天文学会  2000年4月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • オリオン ネビュラ クラスターのチャンドラX線観

    Y.Tsuboi, ABC

    2000年度春季天文学会予稿集,日本天文学会  2000年4月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • Chandra ACIS observation of the Orion Nebula Cluster

    Feigelson, E.D

    Bulletin of the American Astronomical Society,アメリカ天文学会  1999年12月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • Chandra/ACIS Observations of 30 Doradus

    Townsley, L

    Bulletin of the American Astronomical Society,アメリカ天文学会  1999年12月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • X-ray activities in a Young Open Cluster: Chandra Observations of NGC2516

    Tsuboi.Y, Feigelson, E.D, Maeda.Y

    Bulletin of the American Astronomical Society,アメリカ天文学会  1999年12月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • X-Ray Study of the Bright W-R Star HD 93162 with Chandra

    Maeda.Y, Tsuboi.Y

    Bulletin of the American Astronomical Society,アメリカ天文学会  1999年12月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • ASCA Spectra of the Central Star of the Orion Nebula: a Magnetic O Star

    Gagne, M

    Bulletin of the American Astronomical Society,アメリカ天文学会  1999年4月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • X-ray Spectral Variability of Eta Carinae

    Corcoran, M.F

    Bulletin of the American Astronomical Society,アメリカ天文学会  1997年12月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • rho-Oph分子雲のX線描像

    坪井陽子

    LMSA Science Workshop『LMSA計画と高エネルギー天文学』収録,野辺山電波観測所  1997年9月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • 衛星搭載用X線CCDの評価システムの開発

    前田良知

    1997年春季物理学会予稿集,日本物理学会  1997年3月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • 原始星からのX線~rho Oph分子雲~

    坪井陽子, 鎌田祐一, 小山勝二, 関本裕太郎

    ラインX線・ガンマ線による天体物理(V)収録,宇宙科学研究所  1997年1月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • CCD Cal装置の開発装置(I)

    前田良知

    ラインX線・ガンマ線による天体物理(V)収録,宇宙科学研究所  1997年1月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • 原始星のX線と双極分子流構造

    坪井陽子, 小山勝二, 鎌田祐一, 関本裕太郎

    重点領域高エネルギー天体”葉山研究会収録,宇宙線研究所  1996年12月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • 前主系列星巨大フレアのプラズマ診断~V773 TauのX線フレア~

    坪井陽子, 上野史郎, 小山勝二

    1996年度秋季天文学会予稿集,日本天文学会  1996年10月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • ASCAによる星生成領域の観測

    坪井陽子

    1996年科学衛星・宇宙観測シンポジウム収録,宇宙科学研究所  1996年7月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • V773 TauからのX線フレア観測

    坪井陽子, 上野史郎, 小山勝二

    1996年度日本天文学会春季年会予稿集,日本天文学会  1996年3月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • 星生成領域からのX線放射~V773 Tauからの巨大X線フレア観測~

    坪井陽子, 上野史郎, 小山勝二

    ラインX線・ガンマ線による天体物理(IV)収録,宇宙科学研究所  1995年11月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • 硬X線による星生成領域の観測

    坪井陽子, 小山勝二

    1995年日本天文学会秋季年会予稿集,日本天文学会  1995年10月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • X線で探る恒星の生成過程~Herbig Ae/Be starの観測~

    坪井陽子, 小山勝二, 冨田和学

    重点領域研究「星間物質とその進化」大研究会収録,宇宙科学研究所  1995年8月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • Spatial and Spectral structure of eta Car

    坪井陽子, 小山勝二

    1995年度日本天文学会春季年会予稿集,日本天文学会  1995年3月 

     詳細を見る

    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • Carina Nebulaに拡がるX線起源の考察

    坪井陽子

    原始惑星系円盤ワークショップ収録,国立天文台  1995年3月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • eta Carの空間及びスペクトル構造

    坪井陽子, 小山勝二

    太陽および恒星の超高温、高エネルギー現象研究会収録,国立天文台  1995年2月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • X線放射と原始星の進化2;大質量星

    坪井陽子

    重点領域研究「星間物質とその進化」大研究会収録,宇宙科学研究所  1994年12月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

  • eta Carの空間及びスペクトル構造

    坪井陽子, 小山勝二

    ラインX線・ガンマ線による天体物理(III)収録,宇宙科学研究所  1994年11月 

     詳細を見る

    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

    researchmap

▼全件表示

Works(作品等)

  • 硬X線撮像分光による原始星の構造と進化の研究

    2005年 - 2006年

     詳細を見る

  • 硬X線撮像分光による原始星の高空間分解能探査

    2003年 - 2005年

     詳細を見る

共同研究・競争的資金等の研究課題

  • 大型国際X線天文衛星計画Athenaの科学成果最大化

    2020年4月 - 2022年3月

    文部科学省  科学研究費補助金(日本学術振興会・文部科学省)-基盤研究(B) 

      詳細を見る

    資金種別:競争的資金

    researchmap

  • 分光・偏光・撮像の3大観測能力を高いレベルで備えた新しいX線望遠鏡の開発

    2019年4月 - 2021年3月

    文部科学省  科学研究費補助金(日本学術振興会・文部科学省)-基盤研究(B) 

      詳細を見る

    資金種別:競争的資金

    researchmap

  • 恒星ハイパーフレアの発生環境の解明

    2017年4月 - 2020年3月

    文部科学省  科学研究費補助金(日本学術振興会・文部科学省)-基盤研究(C) 

    坪井陽子

      詳細を見る

    資金種別:競争的資金

    近年、太陽フレアのさらに10-10000 倍ものエネルギーを放出するフレア(スーパーフレアと呼ばれる)が恒星の可視光観測で発見されている(例えば Maehara et al. 2012 Nature など)。このスーパーフレアが太陽でもし起これば、地球規模の大停電やオゾン層破壊など、我々の社会に多大な打撃が加わると考えられている。本研究では、発生頻度の少ない巨大フレアをキャッチする能力の高い全天X 線監視装置MAXI を用いて、(1)全天方向に対してスーパーフレアサーチをX 線帯域で行い、(2)星の若さや生成環境と、スーパーフレアの頻度との関係を明らかにする。また(3)フレアループの幾何、位置に新たな情報を与える偏光に高い感度を持つ光学系の開発を行う。

    researchmap

  • X線長期モニターを用いた原始星の統計的研究

    研究課題/領域番号:23540269  2012年4月 - 2014年3月

    文部科学省  科学研究費助成事業 平成24年度 基盤研究(C)  基盤研究(C)  中央大学

    坪井 陽子

      詳細を見る

    資金種別:競争的資金

    配分額:4940000円 ( 直接経費:3800000円 、 間接経費:1140000円 )

    (1)未だ星を形成しつつある初期の原始星(Class 0)がX線を放出していることを確認した。(2) MAXI/GSCで、巨大フレアの発生頻度が太陽フレアと同じ冪でエネルギーとともに落ちること、10桁に渡って黒点の面積がフレア規模と相関していること、HR1099の最大フレアエネルギー、を明らかにした。(3)II Peg を多波長同時観測し、Hα輝線で長期青方変移を、X線帯域で再加熱を観測し、超大規模ツーリボンフレアの証拠を得た。(4)Diamond Like Carbon の成膜により結晶を曲げる技術を確立し、Bragg 反射を用いたX線偏光計として使えること、X線を集光できることを確認した。

    researchmap

  • X線長期モニターを用いた原始星の統計的研究

    研究課題/領域番号:23540269  2011年4月 - 2014年3月

    文部科学省  科学研究費補助金 基盤研究(C)  基盤研究(C)  中央大学

    坪井 陽子

      詳細を見る

    資金種別:競争的資金

    配分額:4940000円 ( 直接経費:3800000円 、 間接経費:1140000円 )

    (1)未だ星を形成しつつある初期の原始星(Class 0)がX線を放出していることを確認した。(2) MAXI/GSCで、巨大フレアの発生頻度が太陽フレアと同じ冪でエネルギーとともに落ちること、10桁に渡って黒点の面積がフレア規模と相関していること、HR1099の最大フレアエネルギー、を明らかにした。(3)II Peg を多波長同時観測し、Hα輝線で長期青方変移を、X線帯域で再加熱を観測し、超大規模ツーリボンフレアの証拠を得た。(4)Diamond Like Carbon の成膜により結晶を曲げる技術を確立し、Bragg 反射を用いたX線偏光計として使えること、X線を集光できることを確認した。

    researchmap

  • 硬X線撮像分光による星生成過程の研究

    研究課題/領域番号:20540237  2008年4月 - 2011年3月

    文部科学省  科学研究費補助金 基盤研究(C)  基盤研究(C)  中央大学

    坪井 陽子

      詳細を見る

    資金種別:競争的資金

    配分額:4420000円 ( 直接経費:3400000円 、 間接経費:1020000円 )

    星誕生の動乱期である原始星本体を透過力の強い硬X線帯域を利用して初検出し、諸物理量(明るさ、時間変動、プラズマの温度など)を明らかにした。またそれらの天体の若さを赤外線観測により確認した。これらと比較すべき他の段階の星からのX線を観測し、X線の放射機構や星風の加速についてスタディした。さらに全天X線監視装置MAXIを用いて星における最も大きなフレアのサンプルを得、フレア頻度や発生するプラズマの諸物理量を明らかにした。X線偏光に感度を持つ光学系を開発した。

    researchmap

  • 科学衛星観測データベースの宇宙科学教育への活用

    2007年4月 - 2009年3月

    文部科学省  科学研究費補助金(日本学術振興会・文部科学省)-基盤研究(B) 

      詳細を見る

    資金種別:競争的資金

    researchmap

  • 硬X線撮像分光による原始星の構造と進化の研究

    研究課題/領域番号:17740109  2005年4月 - 2008年3月

    文部科学省  科学研究費補助金 若手研究(B)  若手研究(B)  中央大学

    坪井 陽子

      詳細を見る

    資金種別:競争的資金

    配分額:2900000円 ( 直接経費:2900000円 )

    1.Chandra衛星でM17 HII領域を観測し、886ものYoung Stellar Objectsを検出した(Broos, et. al. 2007 ApJS)。その40%はAvが10等以上の減光を受けた若い天体であり、IRS5/UC1領域、Kleinmann-Wright天体、M17-Northといった有名な星生成領域や、新たに発見した、2pcの長さの孤状領域、0.1pcスケールの領域にある程度が付随していた。残りの減光を受けた天体は、集団で生まれている星よりも多く、分子雲全体に大きく拡散していた。M17には何百かのClass I原始星候補が存在するとされているが、結局そのうち64個からX線が検出された。
    2.すざく衛星による銀河中心方向のサーベイで、早期A型星から大きなフレアが受かった(Miura, et. al.2008 PASJ)。強い磁場が存在しないとされるA型星から、原始星と共通する大きなフレアが受かったことは驚きに値する。フレアループの磁場の強さは、50gauss、ループの長さは0.05AUと導けた。最も考えられうる放射機構は、そのA型星は他の星と近接連星系をなしており、相互作用を及ぼしあうことによって磁場が増幅されているという説である。
    3.すざく衛星を用いてM17 HII領域の拡がったX線成分を検出した。高電離状態の元素からの輝線を複数検出し、この拡がったプラズマは、300万度程度の単一温度の太陽コロナモデルでフィッティングできること、水素に対する元素の組成比は太陽組成比の0.1-0.3倍であること、元素同士の組成比はNeを除いて大体太陽組成と同等で、Neのみが太陽組成の2倍あることを明らかにした。これらの結果は我々の観測した5pc程度の拡がりのどこでも同じ結果であった。
    4.すざく衛星を用いて、超新星残骸の研究(Bamba, et. al.2008 AdSpR、Takahashi, et. al.2008 PASJ)、および超新星残骸の集合体と考えられているNorth Polar Spur (Miller, et. al. 2008 PASJ)の研究を行った。

    researchmap

  • 硬X線撮像分光による原始星の研究

    研究課題/領域番号:17740109  2004年4月 - 2005年3月

    中央大学  中央大学特定課題研究費  若手研究(B)  中央大学

    坪井 陽子

      詳細を見る

    資金種別:競争的資金

    配分額:2600000円 ( 直接経費:2900000円 )

    1.Chandra衛星でM17 HII領域を観測し、886ものYoung Stellar Objectsを検出した(Broos, et. al. 2007 ApJS)。その40%はAvが10等以上の減光を受けた若い天体であり、IRS5/UC1領域、Kleinmann-Wright天体、M17-Northといった有名な星生成領域や、新たに発見した、2pcの長さの孤状領域、0.1pcスケールの領域にある程度が付随していた。残りの減光を受けた天体は、集団で生まれている星よりも多く、分子雲全体に大きく拡散していた。M17には何百かのClass I原始星候補が存在するとされているが、結局そのうち64個からX線が検出された。
    2.すざく衛星による銀河中心方向のサーベイで、早期A型星から大きなフレアが受かった(Miura, et. al.2008 PASJ)。強い磁場が存在しないとされるA型星から、原始星と共通する大きなフレアが受かったことは驚きに値する。フレアループの磁場の強さは、50gauss、ループの長さは0.05AUと導けた。最も考えられうる放射機構は、そのA型星は他の星と近接連星系をなしており、相互作用を及ぼしあうことによって磁場が増幅されているという説である。
    3.すざく衛星を用いてM17 HII領域の拡がったX線成分を検出した。高電離状態の元素からの輝線を複数検出し、この拡がったプラズマは、300万度程度の単一温度の太陽コロナモデルでフィッティングできること、水素に対する元素の組成比は太陽組成比の0.1-0.3倍であること、元素同士の組成比はNeを除いて大体太陽組成と同等で、Neのみが太陽組成の2倍あることを明らかにした。これらの結果は我々の観測した5pc程度の拡がりのどこでも同じ結果であった。
    4.すざく衛星を用いて、超新星残骸の研究(Bamba, et. al.2008 AdSpR、Takahashi, et. al.2008 PASJ)、および超新星残骸の集合体と考えられているNorth Polar Spur (Miller, et. al. 2008 PASJ)の研究を行った。

    researchmap

  • 硬X線撮像分光による原始星の高空間分解能探査

    2003年4月 - 2005年3月

    文部科学省  科学研究費補助金(若手研究B) 

      詳細を見る

    資金種別:競争的資金

    researchmap

▼全件表示

知的財産権

  • X線分光偏光計

    飯塚 亮

     詳細を見る

    出願番号:特願2016-048851  出願日:2016年3月11日

    公開番号:特開2017-161480  公開日:2017年9月14日

    登録番号:特許第6650301号  登録日:2020年1月22日 

    出願人(機関):学校法人中央大学、国立研究開発法人宇宙航空研究開発機構

  • 湾曲結晶の製造方法および湾曲結晶

    飯塚 亮

     詳細を見る

    出願番号:特願2012-147355  出願日:2012年6月29日

    公開番号:特開2014-009131  公開日:2014年1月20日

    出願人(機関):学校法人中央大学

委員歴

  • 2003年 - 2005年

    日本天文学会   天文教育委員会