Annual parallax and a dimming event of a Mira variable star, FV Bootis

作者：Kamezaki Tatsuya; Nakagawa Akiharu; Omodaka Toshihiro; Inoue Kan ichiro; Chibueze James O^*; Nagayama Takumi; Ueno Yuji; Matsunaga Noriyuki

来源：Publications of the Astronomical Society of Japan, 2016, 68(5): 75.

DOI：10.1093/pasj/psw068

• astrometry
• stars: individual (FV Bootis)
• stars: AGB and post-AGB
• techniques: interferometric

We present the first measurement of the trigonometric parallax of water masers associated with a Mira star, FV Bootis (FV Boo) using VLBI Exploration of Radio Astrometry (VERA). Based on our multi-epoch VERA observations, we derived the parallax to be 0.97 +/- 0.06 mas, which corresponds to a distance of 1.03(-0.06)(+0.07) kpc. The water masers around FV Boo were spatially distributed over an area of 41 au x 41 au, and their internal motions indicate the presence of an outflow. Using the Kagoshima University 1 m optical/infrared telescope, we determined the period to be 305.6 d and the mean apparent magnitude to be +2.91 mag in the K-7-band. On the period-luminosity plane, the obtained period and K-7-band magnitude puts FV Boo slightly below the sequence of Miras, possibly due to circumstellar reddening. Combining our photometric data with COBE and 2MASS datasets spanning over 20 years, we found in the near infrared that FV Boo was significantly fainter in 2005 compared with preceding and later phases. Its color, however, did not show a large variation through this change. We infer that the dimming could be caused by an eclipse due to a cloud in a binary system.

• 出版日期2016-10
• 单位中国科学院国家天文台