Accurate parallax measurement toward the symbiotic star R Aquarii

作者：Min Cheulhong^*; Matsumoto Naoko; Kim Mi Kyoung; Hirota Tomoya; Shibata Katsunori M; Cho Se Hyung; Shizugami Makoto; Honma Mareki

来源：Publications of the Astronomical Society of Japan, 2014, 66(2): 38.

DOI：10.1093/pasj/psu003

• astrometry
• binaries: symbiotic
• instrumentation: interferometers
• masers (SiO)
• stars: individual (R Aquarii)

Multiepoch phase-referencing VLBI (Very Long Baseline Interferometry) observations with VERA (VLBI Exploration of Radio Astrometry) were performed for the symbiotic star R Aquarii (R Aqr) from 2005 September to 2006 October. Tracing one of the nu = 2, J = 1-0 SiO maser spots, we measured an annual parallax of pi = 4.59 +/- 0.24 mas, corresponding to a distance of 218(-11)(+12) pc. Our result is consistent with earlier distance measurements, but yields the highest accuracy of similar to 5% level. Applying our distance, we derived an absolute K-band magnitude of M-K = -7.71 +/- 0.11, which is consistent with the recent period-luminosity relation by VLBI parallax measurements for five OH-Mira variables. In addition, the expansion age of an inner nebula around R Aqr is found to be similar to 240 yr, corresponding to about the year 1773.

• 出版日期2014-4
• 单位中国科学院国家天文台