1. VLBI Astrometry of AGB Variables with VERA -- A Semiregular Variable S Crateris --
- Author
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Nakagawa, Akiharu, Tsushima, Miyuki, Ando, Kazuma, Bushimata, Takeshi, Choi, Yoon Kyung, Hirota, Tomoya, Honma, Mareki, Imai, Hiroshi, Iwadate, Kenzaburo, Jike, Takaaki, Kameno, Seiji, Kameya, Osamu, Kamohara, Ryuichi, Kan-Ya, Yukitoshi, Kawaguchi, Noriyuki, Kijima, Masachika, Kim, Mi Kyoung, Kobayashi, Hideyuki, Kuji, Seisuke, Kurayama, Tomoharu, Maeda, Toshihisa, Manabe, Seiji, Maruyama, Kenta, Matsui, Makoto, Matsumoto, Naoko, Miyaji, Takeshi, Nagayama, Takumi, Nakamura, Kayoko, Nyu, Daisuke, Oh, Chung Sik, Omodaka, Toshihiro, Oyama, Tomoaki, Pradel, Nicolas, Sakai, Satoshi, Sasao, Tetsuo, Sato, Katsuhisa, Sato, Mayumi, Shibata, Katsunori M., Suda, Hiroshi, Tamura, Yoshiaki, Ueda, Kousuke, Ueno, Yuji, and Yamashita, Kazuyoshi
- Subjects
Astrophysics - Abstract
We present a distance measurement for the semiregular variable S Crateris (S Crt) based on its annual parallax. With the unique dual beam system of the VLBI Exploration for Radio Astrometry (VERA) telescopes, we measured the absolute proper motion of a water maser spot associated with S Crt, referred to the quasar J1147-0724 located at an angular separation of 1.23$^{\circ}$. In observations spanning nearly two years, we have detected the maser spot at the LSR velocity of 34.7 km s$^{-1}$, for which we measured the annual parallax of 2.33$\pm$0.13 mas corresponding to a distance of 430$^{+25}_{-23}$ pc. This measurement has an accuracy one order of magnitude better than the parallax measurements of HIPPARCOS. The angular distribution and three-dimensional velocity field of maser spots indicate a bipolar outflow with the flow axis along northeast-southwest direction. Using the distance and photospheric temperature, we estimate the stellar radius of S Crt and compare it with those of Mira variables., Comment: 9 pages, 4 figures, accepted for publication in PASJ (Vol.60, No.5, October 25, VERA special issue)
- Published
- 2008
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