A Trigonometric Parallax of Sgr B2

M. J. Reid(1), K. M. Menten(2), X. W. Zheng(3), A. Brunthaler(2), Y. Xu(4)

(1) Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
(2) Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
(3) Department of Astronomy, Nanjing University Nanjing 210093, China
(4) Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, China

Paper: submitted to ApJ

EPrint Server: 0908.3637


We have measured the positions of H2O masers in Sgr B, a massive star forming region in the Galactic center, relative to an extragalactic radio source with the Very Long Baseline Array. The positions measured at 12 epochs over a time span of one year yield the trigonometric parallax of Sgr B and hence a distance to the Galactic center of Ro=7.9+0.8_-0.7 kpc. The proper motion of Sgr B relative to Sgr A suggests that Sgr B is 0.13 kpc nearer than the Galactic center, assuming a low-eccentricity Galactic orbit.

Preprints available from the authors at reid@cfa.harvard.edu , or the raw TeX (no figures) if you click here.

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