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arXiv 0808.0641astro-ph
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使用VERA与VY大犬座的距离

Distance to VY Canis Majoris with VERA

Yoon Kyung Choi, Tomoya Hirota, Mareki Honma, Hideyuki Kobayashi, Takeshi Bushimata, Hiroshi Imai, Kenzaburo Iwadate, Takaaki Jike, Seiji Kameno, Osamu Kameya, … 展开作者

Yoon Kyung Choi, Tomoya Hirota, Mareki Honma, Hideyuki Kobayashi, Takeshi Bushimata, Hiroshi Imai, Kenzaburo Iwadate, Takaaki Jike, Seiji Kameno, Osamu Kameya, Ryuichi Kamohara, Yukitoshi Kan-ya, Noriyuki Kawaguchi, Masachika Kijima, Mi Kyoung Kim, Seisuke Kuji, Tomoharu Kurayama, Seiji Manabe, Kenta Maruyama, Makoto Matsui, Naoko Matsumoto, Takeshi Miyaji, Takumi Nagayama, Akiharu Nakagawa, Kayoko Nakamura, Chung Sik Oh, Toshihiro Omodaka, Tomoaki Oyama, Satoshi Sakai, Tetsuo Sasao, Katsuhisa Sato, Mayumi Sato, Katsunori M. Shibata, Yoshiaki Tamura, Miyuki Thushima, Kazuyoshi Yamashita

备注：
7 pages, 4 figures, accepted for publication in PASJ, VERA special issue
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摘要：

本文报道了利用VLBI射电天体测量探测（VERA）对红巨星大犬座VY（VY CMa）周围的H2O脉泽进行的天体测量观测。基于13个月的天体测量监测，我们成功地测量了0.88 +/- 0.08 mas的三角视差，对应于1.14 + 0.11/-0.09 kpc的距离。这是到VY CMa的最精确距离，也是第一个基于年度视差测量的距离。VY CMa的光度由于先前接受的距离而被高估。根据我们的结果，我们重新估计VY CMa的光度为（3 +/- 0.5）x 10^5 L_sun，使用光学和红外波长上的热通量积分。这一改进的光度值使得VY CMa在赫兹-罗素（HR）图上的位置比以前的位置更接近理论上允许的区域（即Hayashi轨迹的左侧），尽管恒星表面有效温度的不确定性仍然不允许我们做出最终结论。

英文摘要：

We report astrometric observations of H2O masers around the red supergiant VY Canis Majoris (VY CMa) carried out with VLBI Exploration of Radio Astrometry (VERA). Based on astrometric monitoring for 13 months, we successfully measured a trigonometric parallax of 0.88 +/- 0.08 mas, corresponding to a distance of 1.14 +0.11/-0.09 kpc. This is the most accurate distance to VY CMa and the first one based on an annual parallax measurement. The luminosity of VY CMa has been overestimated due to a previously accepted distance. With our result, we re-estimate the luminosity of VY CMa to be (3 +/- 0.5) x 10^5 L_sun using the bolometric flux integrated over optical and IR wavelengths. This improved luminosity value makes location of VY CMa on the Hertzsprung-Russel (HR) diagram much closer to the theoretically allowable zone (i.e. the left side of the Hayashi track) than previous ones, though uncertainty in the effective temperature of the stellar surface still does not permit us to make a final conclusion.

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