SiO maser survey of the galactic disk IRAS sources. II. vertical bar l vertical bar <= 3 degrees and vertical bar b vertical bar <= 3 degrees, the Galactic center area
S. Deguchi et al., SiO maser survey of the galactic disk IRAS sources. II. vertical bar l vertical bar <= 3 degrees and vertical bar b vertical bar <= 3 degrees, the Galactic center area, ASTROPH J S, 128(2), 2000, pp. 571-595
A survey has been made in the SiO J = 1-0, upsilon = 1 and 2 transitions (s
imilar to 43 GHz) for color-selected IRAS sources in the Galactic-center re
gion of \l\ less than or equal to 3 degrees and \b\ less than or equal to 3
degrees using the Nobeyama 45 m telescope. We have detected 86 of 176 obse
rved sources in the SiO masers. Distances to the sources are deduced from I
RAS 12 and 25 mu m flux densities and range approximately from 5 to 12 kpc.
Radial velocities of the detected sources spread between -300 and 310 km s
(-1). The longitude-velocity (I-v) diagram exhibits an empty region of sour
ces at I = -0.degrees 4-1.degrees 0 and V-lsr = 20-150 km s(-1), which is i
nterpreted as an undersampling effect of sources in the IRAS catalog at the
Galactic central disk. The rotation rate, velocity dispersion, tilt angle
of the rotation axis, and velocity shift at I = 0 degrees are derived by fi
tting the velocities of the sources with a straight line as a function of G
alactic longitude. These quantities are compatible with those obtained from
previous observations of bulge stars with \b\ > 3 degrees. The average rad
ial velocity of subsamples of stars tends to increase with distance, sugges
ting the presence streaming motion of stars in a barlike bulge. We conclude
that most of the IRAS sources in the sample belong to the bulge.