SiO maser survey of IRAS sources in the inner galactic disk

Shuji Deguchi, Takahiro Fujii, Ian S. Glass, Hiroshi Imai, Yoshifusa Ita, Hideyuki Izumiura, Osamu Kameya, Atsushi Miyazaki, Yoshikazu Nakada, Jun Ichi Nakashima

Research output: Contribution to journalReview articlepeer-review

49 Citations (Scopus)


We surveyed 401 color-selected IRAS sources in the galactic disk in the SiO J = 1-0, v = 1 and 2 maser lines at 43 GHz, resulting in 254 (239 new) detections. The observed sources lie mostly in a strip of the inner galactic disk with boundaries -10° < l < 40° and |b < 3°. This survey provides radial velocities of inner-disk stars for which optical measurements cannot be made due to interstellar extinction. The SiO l-v diagram in the area -10° < l < 40° exhibits fewer objects coincident with the molecular ring feature than does the OH 1612MHz source l-v map, indicating a slight difference of stellar type between SiO and OH emitting stars. After identifying all of the SiO detected sources in the 2MASS near-infrared catalog, we computed their luminosity distances based on the infrared fluxes. We then mapped these objects onto the first quadrant of the galactic plane. Combining the distances with the SiO radial velocities, we obtained a pattern speed for SiO maser sources, ΩP = 21(±13) km s-1 kpc-1, between the distances 1 and 5.5kpc, without the use of any dynamical models. The increase of the pattern speed toward the galactic center (up to 60km s-1 kpc-1 between the distances, 5.5 and 7kpc) suggests the presence of two pattern speeds in the Galaxy.

Original languageEnglish
Pages (from-to)765-802
Number of pages38
JournalPublication of the Astronomical Society of Japan
Issue number5
Publication statusPublished - 2004


  • Galaxy: disk, kinematics and dynamics
  • Masers
  • Stars: AGB and post-AGB


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