부산대학교 도서관

We report a trigonometric parallax of 12 GHz methanol masers associated with the massive star forming region G9.62+0.20, corresponding to a distance of 5.2+-0.6 kpc. With a local standard of rest velocity of about 2 km/s, the region's kinematic distances of 0.5 and 16 kpc differ greatly from the distance derived here. Our measurement of the peculiar motion of the star forming region shows a very large deviation from a circular Galactic orbit: 41 km/s radially outward from the Galactic center and 60 km/s counter to Galactic rotation. The combination of its radial velocity and distance places G9.62+0.20 in the inner region of the Galaxy close to the Expanding Near 3 kpc-Arm, where the bulge/bar potential has strong gravitational influence. We also map the distribution of 12 GHz methanol masers, locate them with respect to a hypercompact H II region, and compare our data with the periodic flare phenomenon reported previously for this source.
Comment: 16 pages, 4 figures, 2 tables, accepted by The Astrophysical Journal