Astrometry of Galactic Star-Forming Region ON2N with VERA: Estimation of the Galactic Constants
Astrometry of Galactic Star-Forming Region ON2N with VERA: Estimation of the Galactic Constants
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DOI：
10.1093/pasj/63.1.45
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发表时间：
2010-12
影响因子：
2.3
通讯作者：
K. Ando;T. Nagayama;T. Omodaká;T. Handa;H. Imai;A. Nakagawa;H. Nakanishi;M. Honma;H. Kobayashi;T. Miyaji
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文献类型：
--
作者：
K. Ando;T. Nagayama;T. Omodaká;T. Handa;H. Imai;A. Nakagawa;H. Nakanishi;M. Honma;H. Kobayashi;T. Miyaji
We performed the astrometry of H2O masers in the Galactic star-forming region Onsala 2 North (ON 2 N) with the VLBI Exploration of Radio Astrometry (VERA). We obtained a trigonometric parallax of 0.261 ˙ 0.009 mas, corresponding to a heliocentric distance of 3.83 ˙ 0.13 kpc. ON 2 N is expected to be on the solar circle, because its radial velocity with respect to the local standard of rest (LSR) is nearly zero. By using the present parallax and proper motions of the masers, the galactocentric distance of the Sun and the Galactic rotation velocity at the Sun are found to be R0 = 7.80 ˙ 0.26 kpc and Θ0 = 213 ˙ 5k m s � 1 , respectively. The ratio of Galactic constants, namely the angular rotation velocity of the LSR, can be determined more precisely, and is found to be Ω0 =Θ 0=R0 = 27.3 ˙ 0.8 km s � 1 kpc � 1 , which is consistent with recent estimations, but different from 25.9 km s � 1 kpc � 1 derived from the recommended values of Θ0 and R0 by the International Astronomical Union (1985).
