Sio maser survey of the galactic disk IRAS sources. III. -10° <l<15° and | b | ≤3°, a central part of the Galaxy

Abstract

A survey has been made in the SiO J = 1-0, v = 1 and 2 transitions (∼43 GHz) for the color-selected IRAS sources in the central region of the Galaxy, -10° <l<15° (except |l| ≤ 3°) and |b| ≤ 3°, with the Nobeyama 45 m telescope. We have detected 124 out of 200 observed sources in SiO masers. Distances to the sources range approximately from 2 to 11 kpc, if estimated from the IRAS 12 and 25 μm flux densities. Radial velocities of the detected sources spread between ± 260 km s-1. The distribution of SiO sources in the longitude-velocity diagram is compared with the H I contours. A number of sources are out of the H I limiting velocities; a group of negative-velocity (∼ -200 to -80 km s-1) sources is found at l = 3°-12° region. The subsamples of sources exhibit negative and positive shifts of the average radial velocity depending on distance, suggesting evidence of a streaming motion of stars in the bulge bar.