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Akihiro DOI

  (土居 明広)

Profile Information

Affiliation
Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency
School of Physical Sciences Department of Space and Astronautical Science, The Graduate University for Advanced Studies
Degree
博士 (理学)(Mar, 2005, 東京大学)
Researcher number
90403641
ORCID ID
 https://orcid.org/0000-0003-4384-9568
J-GLOBAL ID
201101033666007265
researchmap Member ID
B000004312

Research Interests

 11

Research Areas

 3

Research History

 3

Papers

 118
  • Kazunori Akiyama, Kotaro Niinuma, Kazuhiro Hada, Akihiro Doi, Yoshiaki Hagiwara, Aya Higuchi, Mareki Honma, Tomohisa Kawashima, Dimitar Kolev, Shoko Koyama, Sho Masui, Ken Ohsuga, Hidetoshi Sano, Hideki Takami, Yuh Tsunetoe, Yoshinori Uzawa, Takuya Akahori, Yuto Akiyama, Peter Galison, Takayuki J. Hayashi, Tomoya Hirota, Makoto Inoue, Yuhei Iwata, Michael Johnson, Motoki Kino, Yutaro Kofuji, Yosuke Mizuno, Kotaro Moriyama, Hiroshi Nagai, Kenta Nakamura, Shota Notsu, Fumie Ono, Yoko Oya, Tomoaki Oyama, Hannah Rana, Hiromi Saida, Ryo Saito, Yoshihiko Saito, Mahito Sasada, Satoko Sawada-Satoh, Mikiya M. Takahashi, Mieko Takamura, Edward Tong, Hiroyuki Tsuji, Shogo Yoshioka, Yoshimasa Watanabe
    Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave, 91-91, Aug 23, 2024  
  • Kohji Tsumura, Hideo Matsuhara, Koji S. Kawabata, Hiroshi Akitaya, Shuji Matsuura, Haruki Fukui, Akihiro Miyasaka, Keisuke Shinozaki, Akihiro Doi, Daisuke Yonetoku
    Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave, 86-86, Aug 23, 2024  
  • Koji S. Kawabata, Kohji Tsumura, Daisuke Yonetoku, Hideo Matsuhara, Shuji Matsuura, Akihiro Doi, Hiroshi Akitaya, Tomoya Hori
    Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave, 203-203, Aug 23, 2024  
  • Daisuke Yonetoku, Akihiro Doi, Tatehiro Mihara, Hideo Matsuhara, Takanori Sakamoto, Kohji Tsumura, Kunihito Ioka, Makoto Arimoto, Teruaki Enoto, Kenjiro Fujimoto, Hatsune Goto, Shuichi Gunji, Junko S. Hiraga, Shintaro Ikunaga, Nobuyuki Kawai, Ryuji Kondo, Shunsuke Kurosawa, Junyi Li, Yoshitomo Maeda, Ikuyuki Mitsuishi, Toshio Murakami, Issin Nagataka, Yujin Nakagawa, Naoki Ogino, Taiki Owari, Ryuji Sato, Masataka Sato, Tomoya Sato, Tatsuya Sawano, Motoko Serino, Hsien-Chieh Shen, Satoshi Sugita, Shuta Takahashi, Toru Tamagawa, Keisuke Tamura, Takaaki Tanaka, Toru Tanimori, Makoto S. Tashiro, Takumi Togashi, Hiroshi Tomida, Keito Watanabe, Kazutaka Yamaoka, Makoto Yamauchi, Yoichi Yatsu, Atsumasa Yoshida, Hiroshi Akitaya, Akihiko Fukui, Haruki Fukui, Yoshifusa Ita, Koji Kawabata, Shuji Matsuura, Akihiro Miyasaka, Kentaro Motohara, Norio Narita, Hirofumi Noda, Hirofumi Okita, Kei Sano, Keisuke Shinozaki, Sou Tajima, Yuji Urata, Takehiko Wada, Kenshi Yanagisawa, Michitoshi Yoshida, Nobutaka Bando, Ichiro Jikuya, Kenji Minesugi, Yasuyuki Miyazaki, Yusuke Kono, Naoki Takase, Shunichi Nakatsubo, Tooru Kaga, Katsuaki Asano, Kohei Inayoshi, Susumu Inoue, Hirotaka Ito, Hideyuki Izumiura, Norita Kawanaka, Tomoya Kinugawa, Shota Kisaka, Kenta Kiuchi, Kotaro Kyutoku, Jin Matsumoto, Akira Mizuta, Kohta Murase, Hiroki Nagakura, Shigehiro Nagataki, Yoshikazu Nakada, Takashi Nakamura, Yuu Niino, Yudai Suwa, Keitaro Takahashi, Takahiro Tanaka, Kenji Toma, Tomonori Totani, Ryo Yamazaki, Jun'ichi Yokoyama, Yuichi Harikane, Masaomi Tanaka, Shigeo Kimura, Mariko Kimura
    Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray, 75-75, Aug 21, 2024  
  • Shuta Takahashi, Makoto Arimoto, Hatsune Goto, Ryuji Kondo, Daisuke Yonetoku, Robert Hartmann, Lothar Strueder, Peter Holl, Naoki Ogino, Tatsuya Sawano, Junko Hiraga, Masataka Sato, Takanori Sakamoto, Hsien-Chieh Shen, Satoshi Hatori, Ryoya Ishigami, Akihiro Doi, Hideo Matsuhara
    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, 1064, Jul, 2024  Peer-reviewed
More

Misc.

 87
  • 村田泰宏, 望月奈々子, 竹内央, 坪井昌人, 土居明広, 朝木義晴, 中島潔, 山本善一, 上原顕太, 山口健太郎, 河野裕介, 金口政弘, 川口則幸, 藤沢健太
    日本天文学会年会講演予稿集, 2014 246, Feb 20, 2014  
  • Satomi Nakahara, Kazuhiro Hada, Mareki Honma, Hiroyuki Nakanishi, Akihiro Doi
    Proceedings of Science, 2014  
  • 土居明広, 河野裕介, 小山友明, 木村公洋, 岡田望, 佐藤泰貴, 松本尚子, 本間希樹, 鈴木駿策, 金口政弘, 秋山和徳, 上原顕太, 中原聡美
    日本天文学会年会講演予稿集, 2014, 2014  
  • 岡田望, 木村公洋, 大西利和, 小川英夫, 河野裕介, 小山友明, 松本尚子, 山下一芳, 鈴木駿策, 金口政弘, 本間希樹, 秋山和徳, 上原顕太, 中原聡美, 土居明広, 佐藤泰貴
    日本天文学会年会講演予稿集, 2014, 2014  
  • Kazuhiro Hada, Marcello Giroletti, Gabriele Giovannini, Akihiro Doi, Motoki Kino, Hiroshi Nagai, Mareki Honma, Noriyuki Kawaguchi
    Proceedings of the International Astronomical Union, 9(304) 106-107, 2014  
  • Keiichi Asada, Masanori Nakamura, Akihiro Doi, Hiroshi Nagai, Makoto Inoue
    ASTROPHYSICAL JOURNAL LETTERS, 781(1), Jan, 2014  
  • Kazuhiro Hada, Akihiro Doi, Hiroshi Nagai, Makoto Inoue, Mareki Honma, Marcello Giroletti, Gabriele Giovannini
    ASTROPHYSICAL JOURNAL, 779(1), Oct 2, 2013  
  • HAGIWARA Yoshiaki
    106(10) 660-665, Sep 20, 2013  
  • Kazuhiro Hada, Motoki Kino, Akihiro Doi, Hiroshi Nagai, Mareki Honma, Yoshiaki Hagiwara, Marcello Giroletti, Gabriele Giovannini, Noriyuki Kawaguchi
    ASTROPHYSICAL JOURNAL, 775(1), Aug 7, 2013  
  • Takayuki J. Hayashi, Akihiro Doi, Hiroshi Nagai
    May 15, 2013  
    We conducted the first multi-frequency polarimetric imaging of four broad<br /> absorption line (BAL) quasars using Very Long Baseline Array at milli-arcsecond<br /> resolutions to investigate the inclination of the non-thermal jet and test the<br /> hypothesis that radio sources in BAL quasars are still young. Among these four<br /> sources, J0928+446, J1018+0530, and J1405+4056 show one-sided structures in<br /> parsec scales, and polarized emission detected in the core. These<br /> characteristics are consistent with those of blazars. We set constraints on<br /> viewing angles to $&lt;$66 deg for these jets, in the framework of a Doppler<br /> beaming effect. J1159+0112 exhibits an unpolarized gigahertz peaked spectrum<br /> component and several discrete blobs with steep spectra on both sides of the<br /> central component across $\sim$1 kpc. These properties are consistent with<br /> those of young radio sources. We discuss the structures of jets and AGN wind.
  • Takahashi Hiroaki
    Meeting abstracts of the Physical Society of Japan, 68(1) 138-138, Mar 26, 2013  
  • KADOTA Akiko, FUJISAWA Kenta, SAWADA SATOH Satoko, WAJIMA Kiyoaki, DOI Akihiro
    Publications of the Astronomical Society of Japan, 64(5) "109-1"-"109-8", Oct 25, 2012  
  • Kazuhiro Hada, Motoki Kino, Hiroshi Nagai, Akihiro Doi, Yoshiaki Hagiwara, Mareki Honma, Marcello Giroletti, Gabriele Giovannini, Noriyuki Kawaguchi
    ASTROPHYSICAL JOURNAL, 760(1), Oct 18, 2012  
  • 土居明広, 柳楽央至, 川勝望, 紀基樹, 永井洋, 浅田圭一
    日本天文学会年会講演予稿集, 2012 204, Aug 20, 2012  
  • K. Fujisawa, K. Hachisuka, K. Sugiyama, A. Doi, M. Honma, Y. Yonekura, T. Hirota, S. Sawada-Satoh, Y. Murata, K. Motogi, H. Ogawa, X. Chen, K. T. Kim, Z. Q. Shen
    Proceedings of the International Astronomical Union, 8(287) 288-289, Jul, 2012  Peer-reviewed
  • Hiroshi Nagai, Monica Orienti, Motoki Kino, Kenta Suzuki, Gabriele Giovannini, Akihiro Doi, Keiichi Asada, Marcello Giroletti, Jun Kataoka, Filippo D'Ammando, Makoto Inoue, Anne Lahteenmaki, Merja Tornikoski, Jonathan Leon-Tavares, Seiji Kameno, Uwe Bach
    Monthly Notices of the Royal Astronomical Society: Letters, 423(1), Apr 6, 2012  
  • 土居明広, 柳楽央至, 川勝望, 紀基樹, 永井洋, 浅田圭一
    日本天文学会年会講演予稿集, 2012 221, Feb 20, 2012  
  • Kenta Suzuki, Hiroshi Nagai, Motoki Kino, Jun Kataoka, Keiichi Asada, Akihiro Doi, Makoto Inoue, Monica Orienti, Gabriele Giovannini, Marcello Giroletti, Anne Lähteenmäki, Merja Tornikoski, Jonathan León-Tavares, Uwe Bach, Seiji Kameno, Hideyuki Kobayashi
    Astrophysical Journal, 746(2), Dec 4, 2011  
  • Akihiro Doi, Kotaro Kohno, Kouichiro Nakanishi, Seiji Kameno, Makoto Inoue, Kazuhiro Hada, Kazuo Sorai
    Jun 15, 2011  
    The nearby low-luminosity active galactic nucleus (LLAGN) NGC 4258 has a weak<br /> radio continuum emission at the galactic center. Quasi-simultaneous<br /> multi-frequency observations using the Very Large Array (VLA) from 5 GHz (6 cm)<br /> to 22 GHz (1.3 cm) showed inverted spectra in all epochs, which were<br /> intra-month variable, as well as complicated spectral features that cannot be<br /> represented by a simple power law, indicating multiple blobs in nuclear jets.<br /> Using the Nobeyama Millimeter Array (NMA), we discovered a large amplitude<br /> variable emission at 100 GHz (3 mm), which had higher flux densities at most<br /> epochs than those of the VLA observations. A James Clerk Maxwell Telescope<br /> (JCMT) observation at 347 GHz (850 micron) served an upper limit of dust<br /> contamination. The inverted radio spectrum of the nucleus NGC 4258 is<br /> suggestive of an analogy to our Galactic center Sgr A*, but with three orders<br /> of magnitude higher radio luminosity. In addition to the LLAGN M 81, we discuss<br /> the nucleus of NGC 4258 as another up-scaled version of Sgr A*.
  • 村田泰宏, 紀伊恒男, 満田和久, 吉原圭介, 小松敬治, 後藤健, 石村康生, 齋藤宏文, 坂井真一郎, 坪井昌人, 岩田隆浩, 土居明広, 望月奈々子, 永井洋, 亀谷和久, 川原康介, 竹内央, 朝木義晴, 河野祐介, 鈴木駿作, 小林秀行, 梅本智文, 萩原喜昭, 紀基樹, 武士俣健, 川口則行, 小川英夫, 木村公洋, 樋口健, 岸本直子, 亀野誠二, 今井裕, 面高俊宏, 須藤広志
    日本天文学会年会講演予稿集, 2010 242, Aug 20, 2010  
  • 坪井昌人, 斉藤宏文, 村田泰宏, 満田和久, 紀伊恒男, 吉原圭介, 土居明広, 望月奈々子, 亀谷和久, 吉川真, 竹内央, 朝木義晴, 小松敬治, 樋口健, 橋本樹明, 後藤健, 佐藤英一, 石村康正, 坂井真一郎, 岸本直子, 太刀川純孝, 小林秀行, 梅本智文, 萩原喜昭, 河野祐介, 永井洋, 紀基樹, 氏原秀樹, 小川英夫, 木村公洋, 春日隆, 亀野誠二, 藤沢健太, 浅田圭一, 井上允
    日本天文学会年会講演予稿集, 2010 245, Feb 20, 2010  
  • 坪井昌人, 斉藤宏文, 村田泰宏, 川原康介, 吉原圭介, 亀谷和久, 紀伊恒男, 土居明広, 望月奈々子, 吉川真, 竹内央, 朝木義晴, 小松敬治, 樋口健, 橋本樹明, 坂井真一郎, 岸本直子, 太刀川純孝, 小林秀行, 川口則行, 萩原喜昭, 河野祐介, 氏原秀樹, 永井洋, 梅本智文, 紀基樹, 平林久, 小川英夫, 木村公洋, 阿部安宏, 春日隆, 亀野誠二, 西尾正則, 但木兼一, 佐藤麻美子, 藤沢健太, 輪島清昭, 楠野こず枝, 浅田圭一, 井上允
    日本天文学会年会講演予稿集, 2009 254, Aug 20, 2009  
  • 村田泰宏, 齋藤宏文, 坪井昌人, 土居明広, 望月奈々子, 亀谷和久, 紀伊恒男, 川原康介, 吉原圭介, 竹内央, 朝木義晴, 樋口健, 岸本直子, 坂井真一郎, 小松敬治, 太刀川純孝, 平林久, 小林秀行, 武士俣健, 鈴木駿作, 梅本智文, 萩原喜昭, 河野祐介, 氏原秀樹, 紀基樹, 永井洋, 川口則行, 浅田圭一, 井上允, 小川英夫, 木村公洋, 春日隆, 亀野誠二, 今井裕, 面高俊宏, 佐藤麻美子, 但木謙一, 藤沢健太, 輪島清昭, 須藤広志
    日本天文学会年会講演予稿集, 2009 254, Aug 20, 2009  
  • KUROIWA Koichi, KIMURA Kimihiro, OGAWA Hideo, CHIBA Masakatsu, UZIHARA Hideki, KASUGA Takashi, DOI Akihiro, MURATA Yasuhiro, TSUBOI Masato, MITANI Tomohiko
    IEICE technical report, 109(1) 1-5, Apr 2, 2009  
    We developed off-set Cassegrain antenna optical system and 8GHz band receiver for the ASTRO-G/VSOP-2 satellite. That is second generation satellite for the Space VLBI project, which is combing radio telescopes on the earth and the satellite. There are 43,22,8GHz band feed horns at Cassegrain focus. Feed horn of this satellite must have low cross polarization characteristic and small size. Multimode horn satisfies this conditions and have advantage in fabrication, which is short axial length and have simple wall. We introduce the Cassegrain antenna optical system with multimode horn and the 8GHz band receiver.
  • 坪井昌人, 斉藤宏文, 太刀川純孝, 村田泰宏, 紀伊恒男, 土居明広, 望月奈々子, 吉川真, 竹内央, 朝木義晴, 小松敬治, 樋口健, 橋本樹明, 坂井真一郎, 岸本直子, 浅田圭一, 川原康介, 吉原圭介, 亀谷和久, 井上允, 小林秀行, 川口則行, 萩原喜昭, 河野祐介, 氏原秀樹, 永井洋, 梅本智文, 紀基樹, 平林久, 小川英夫, 木村公洋, 阿部安宏, 春日隆, 亀野誠二, 西尾正則, 但木兼一, 佐藤麻美子, 藤沢健太, 輪島清昭
    日本天文学会年会講演予稿集, 2009 249, Feb 20, 2009  
  • 村田泰宏, 齋藤宏文, 坪井昌人, 土居明広, 望月奈々子, 浅田圭一, 亀谷和久, 紀伊恒男, 川原康介, 吉原圭介, 吉川真, 竹内央, 朝木義晴, 樋口健, 岸本直子, 坂井真一郎, 小松敬治, 太刀川純孝, 平林久, 井上允, 武士俣健, 鈴木駿作, 梅本智文, 萩原喜昭, 河野祐介, 氏原秀樹, 紀基樹, 永井洋, 小林秀行, 川口則行, 小川英夫, 木村公洋, 春日隆, 亀野誠二, 今井裕, 面高俊宏, 佐藤麻美子, 但木謙一, 藤沢健太, 輪島清昭
    日本天文学会年会講演予稿集, 2009 247, Feb 20, 2009  
  • 坪井昌人, 齋藤宏文, 太刀川純孝, 村田泰宏, 紀伊恒男, 土居明広, 望月奈々子, 紀基樹, 吉川真, 竹内央, 朝木義晴, 小松敬治, 樋口健, 橋本樹明, 坂井真一郎, 岸本直子, 浅田圭一, 川原康介, 吉原圭介, 井上允, 小林秀行, 川口則行, 萩原喜昭, 河野祐介, 氏原秀樹, 永井洋, 梅本智文, 平林久, 小川英夫, 木村公洋, 阿部安宏, 春日隆, 亀野誠二, 西尾正則, 佐藤麻美子, 藤沢健太, 輪島清昭
    日本天文学会年会講演予稿集, 2008 258, Aug 20, 2008  
  • 村田泰宏, 齋藤宏文, 坪井昌人, 土居明広, 望月奈々子, 紀基樹, 紀伊恒男, 吉川真, 竹内央, 朝木義晴, 小松敬治, 樋口健, 橋本樹明, 坂井真一郎, 岸本直子, 太刀川純孝, 浅田圭一, 川原康介, 平林久, 井上允, 小林秀行, 川口則幸, 萩原喜昭, 河野祐介, 氏原秀樹, 永井洋, 梅本智文, 武士俣健, 亀野誠二, 面高俊宏, 西尾正則, 今井裕, 小川英夫, 木村公洋, 阿部安宏, 春日隆, 藤沢健太, 輪島清昭
    日本天文学会年会講演予稿集, 2008 258, Aug 20, 2008  
  • SUGIYAMA Koichiro, FUJISAWA Kenta, DOI Akihiro, HONMA Mareki, KOBAYASHI Hideyuki, BUSHIMATA Takeshi, MOCHIZUKI Nanako, MURATA Yasuhiro
    Publications of the Astronomical Society of Japan, 60(1) 23-35, Feb 25, 2008  
  • 村田泰宏, 斉藤宏文, 坪井昌人, 太刀川純孝, 土居明広, 望月奈々子, 紀基樹, 吉川真, 竹内央, 朝木義晴, 小松敬治, 樋口健, 橋本樹明, 坂井真一郎, 岸本直子, 浅田圭一, 川原康介, 平林久, 井上允, 小林秀行, 川口則幸, 萩原喜昭, 河野祐介, 氏原秀樹, 永井洋, 梅本智文, 亀野誠二, 面高俊宏, 小川英夫, 木村公洋, 阿部安宏, 春日隆, 藤沢健太, 輪島清昭
    日本天文学会年会講演予稿集, 2008 264, Feb 20, 2008  
  • 坪井昌人, 斉藤宏文, 太刀川純孝, 村田泰宏, 土居明広, 望月奈々子, 紀基樹, 吉川真, 竹内央, 朝木義晴, 小松敬治, 樋口健, 橋本樹明, 坂井真一郎, 岸本直子, 浅田圭一, 川原康介, 井上允, 小林秀行, 川口則幸, 萩原喜昭, 河野祐介, 氏原秀樹, 永井洋, 梅本智文, 平林久, 小川英夫, 木村公洋, 阿部安宏, 春日隆, 亀野誠二, 西尾正則, 佐藤麻美子, 藤沢健太, 輪島清昭
    日本天文学会年会講演予稿集, 2008 262, Feb 20, 2008  
  • 坪井昌人, 斉藤宏文, 太刀川純孝, 村田泰宏, 土居明広, 望月奈々子, 紀基樹, 吉川真, 朝木義晴, 竹内央, 樋口健, 橋本樹明, 坂井真一郎, 岸本直子, 浅田圭一, 川原康介, 井上允, 小林秀行, 萩原喜昭, 河野祐介, 氏原秀樹, 永井洋, 梅本智文, 平林久, 小川英夫, 木村公洋, 阿部安宏, 春日隆, 亀野誠二, 西尾正則, 佐藤麻美子, 藤沢健太, 輪島清昭
    日本天文学会年会講演予稿集, 2007 281, Aug 20, 2007  
  • 竹内央, 吉川真, 加藤隆二, 朝木義晴, 齋藤宏文, 坪井昌人, 村田泰宏, 土居明広, 川原康介, 中村信一, 中村涼, 工藤信夫, 石島義之, 近藤義典, 山元透, 國森裕生, 久保岡俊宏, 後藤忠広, 大坪俊通
    日本天文学会年会講演予稿集, 2007 281, Aug 20, 2007  
  • Koichiro Sugiyama, Kenta Fujisawa, Mareki Honma, Akihiro Doi, Nanako Mochizuki, Yasuhiro Murata, Yasuko Isono
    Proceedings of the International Astronomical Union, 3(242) 176-177, Mar, 2007  Peer-reviewed
  • Akihiro Doi, Kenta Fujisawa, Mareki Honma, Koichiro Sugiyama, Yasuhiro Murata, Nanako Mochizuki, Yasuko Isono
    Proceedings of the International Astronomical Union, 3(242) 148-149, Mar, 2007  Peer-reviewedLead author
  • Hiroshi Nagai, Makoto Inoue, Keiichi Asada, Seiji Kameno, Akihiro Doi
    Astrophys.J.648:148-157,2006, May 12, 2006  
    We present a study of the kinematic and spectral ages of the Gigahertz-Peaked<br /> Spectrum (GPS) source CTD~93. Measurements of the hot spot separation over 8.5<br /> yr show evidence of an increase. The separation rate along the source axis is<br /> 0.34$\pm0.11c$ (H$_{0}$=72 km s$^{-1}$ Mpc$^{-1}$), which results in a<br /> kinematic age of 2200$\pm$700 yr. Assuming that two hot spots are moving apart<br /> at equal speeds, we derive an advance speed of 0.17$\pm0.06c$. The radio lobe<br /> spectra show a high frequency steepening, as expected if energetic electrons<br /> lose energy by synchrotron radiation. The spectral break decreases with the<br /> distance from the hot spot in the northern component of CTD~93. This tendency<br /> is expected from the basic scenario of radio lobe evolution involving particle<br /> acceleration at the hot spots, with the radio lobes populated by high energy<br /> electrons which have leaked from the hot spots. Although a core-jet morphology<br /> for CTD~93 has previously been proposed, these results indicate that the<br /> morphology is similar to that of Compact Symmetric Object (CSO). From the<br /> spectral fits in the northern component we found a break frequency of 3.7 GHz<br /> at the edge of the lobe. The resultant spectral age is $\sim$300 yr assuming<br /> the equipartition magnetic field. This requires the advance speed of 0.26$c$,<br /> which shows a good agreement of the hot spot motion of 0.17$\pm0.06c$. Our<br /> results strongly support the hypothesis that CSOs are young radio sources.
  • Takumi Nagayama, Koji Takeda, Toshihiro Omodaka, Hiroshi Imai, Seiji Kameno, Yoshiaki Sofue, Akihiro Doi, Kenta Fujisawa, Asao Habe, Mareki Honma, Mareki Honma, Noriyuki Kawaguchi, Noriyuki Kawaguchi, Eiji Kawai, Hideyuki Kobayashi, Hideyuki Kobayashi, Yasuhiro Koyama, Yasuhiro Murata, Yasuhiro Murata, Kazuo Sorai, Hiroshi Sudou, Hiroshi Takaba, Sayaka Tamura, Sayaka Tamura, Ken Ichi Wakamatsu
    Publications of the Astronomical Society of Japan, 60 1069-1075  
    We present the proper motions of H2O masers in NML Cygni, observed with the Japanese VLBI Network at three epochs spanning 455 d. We detected about 15 maser features at each epoch. Overall, 13 features that were detected at least twice were tracked by their radial velocities and proper motions. The three-dimensional kinematics of the maser features indicate the presence of an expanding outflow. The major axis of the outflow is estimated to be at a position angle of ∼ 108°, and an inclination angle of ∼ 8° with respect to the line of sight. The H2O masers are located between an apparent minimum radius of ∼ 9.6 × 1012 m (64 AU) and a maximum radius of ∼ 3.0 × 1013 m (202AU), where the expansion velocity increases from 12 to 27 km s-1. A comparison with the distributions of SiO, H2O, and OH masers suggests that the outflow of NML Cygni is expanding outside a radius of ∼ 1.5 × 10 13 m (100 AU). This radius corresponds to 6 stellar radii, and is consistent with the radius of the inner boundary for the dust shell. © 2008. Astronomical Society of Japan.

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