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1Nobeyama Radio Observatory,
National Astronomical Observatory,
Minamimaki, Minamisaku, Nagano 384-1305, Japan
2Okayama Astrophysical Observatory,
National Astronomical Observatory,
Kamogata, Asakuchi, Okayama 719-0232, Japan
3Department of Astronomy,
Faculty of Science, the University of Tokyo,
Bunkyo-ku, Tokyo 113-0032, Japan
4Kiso Observatory, Institute of Astronomy,
Faculty of Science, the University of Tokyo
Mitaka, Tokyo 181-8588, Japan
5Mizusawa Astrogeodynamic Observatory,
National Astronomical Observatory,
Mizusawa, Iwate 023-0861, Japan
6Astronomical Institute,
Osaka Kyoiku University,
Asahigaoka, Kashiwara, Osaka 582-8582
概要:
A survey has been made in the SiO J=1-0, v=1 and 2 transitions
(
GHz) for the color-selected IRAS sources
in the galactic disk area of -10 <l<35
and |b| < 3 with the Nobeyama 45-m telescope.
At present, we have detected about 300 out of 500 observed
sources in SiO masers.
Distances to the sources are deduced by the JHK, IRAS 12, and 25
flux densities and range approximately from 2 kpc to 12 kpc.
The lines of sight of this region cross the location
of the near end of the bar in the Galaxy.
Radial velocities of the detected sources spread
between -200 and 300 . The range slightly exceeds the
possible limits expected from the galactic rotation.
The SiO velocity-longitude (v-l) diagram exhibits several
concentrations of sources in narrow ranges in longitude and velocity
and also exhibits empty regions.
A comparison with the CO and HI v-l diagrams
reveals that the overall distribution of the SiO maser sources
on the v-l diagram resembles to the molecular ring feature.
A group of stars at l
shows
an odd velocity of
85 ,
at which no corresponding CO cloud is found.
The stars with a large deviation of motion from the galactic rotation
are found to fall at a distance of
5.5 kpc from the Sun.
This fact might indicate that the stellar motion deviates strongly from
smooth galactic rotation near to the tip of the bar.
Next: 1 Introduction
Jun Makino
Wed Mar 17 17:53:42 JST 1999