OH/IR stars within 50 parsecs of the Galactic center

Abstract

A search for OH/IR stars close to the Galactic center has been initiated using the VLA at 18 cm. Thirty-three stars were found in a 34 x 34 arcmin field centered on Sgr A West. The strong concentration toward the galactic plane and the bulk rotation around the nucleus reported by Habing et al. in 1983 in a 2 deg field around the Galactic center are confirmed, but the random motion with a dispersion of 60 km/s in the radial direction is less than half the value found by them. The circumstellar shell expansion velocities are higher than found at larger distances from the Galactic center, suggesting a relatively more massive population of stars near the nucleus or a more efficient conversion of radiation pressure to bulk motion of the circumstellar gas. The OH/IR stars are strongly concentrated toward the continuum source Sgr A West, suggesting a pronounced increase in the density of stars toward the Galactic center.