A major star formation region in the receding tip of the stellar Galactic bar

Abstract

We present an analysis of the optical spectroscopy of 58 stars in the Galactic plane at $l=27$\arcdeg, where a prominent excess in the flux distribution and star counts have been observed in several spectral regions, in particular in the Two Micron Galactic Survey (TMGS) catalog. The sources were selected from the TMGS, to have a $K$ magnitude brighter than +5 mag and be within 2 degrees of the Galactic plane. More than 60% of the spectra correspond to stars of luminosity class I, and a significant proportion of the remainder are very late giants which would also be fast evolving. This very high concentration of young sources points to the existence of a major star formation region in the Galactic plane, located just inside the assumed origin of the Scutum spiral arm. Such regions can form due to the concentrations of shocked gas where a galactic bar meets a spiral arm, as is observed at the ends of the bars of face-on external galaxies. Thus, the presence of a massive star formation region is very strong supporting evidence for the presence of a bar in our Galaxy.

13 pages (latex) + 4 figures (eps), accepted in ApJ Lett

Cited by in corpus (26)

• Empirical calibration of the near-IR Ca II triplet - I. The stellar library and index definition
• Detection of the old stellar component of the major Galactic bar
• Tracing the long bar with red-clump giants
• The Long Bar in the Milky Way. Corroboration of an old hypothesis
• The Slope of the Near Infrared Extinction Law
• A third red supergiant rich cluster in the Scutum-Crux Arm
• Strong Evidence that the Galactic Bulge is Shining in Gamma Rays
• A massive association around the obscured open cluster RSGC3
• Another cluster of red supergiants close to RSGC1
• A newly-discovered young massive star cluster at the end of the Galactic Bar
• Major structures of the inner Galaxy delineated by 6.7-GHz methanol masers
• Searching for the in-plane Galactic bar and ring in DENIS
• Inversion of stellar statistics equation for the Galactic Bulge
• Red supergiants around the obscured open cluster Stephenson 2
• A major star formation region in the receding tip of the stellar Galactic bar. II. Supplementary information and evidence that the bar is not the same structure as the triaxial bulge previouly reported
• Initial phases of massive star formation in high infrared extinction clouds. I. Physical parameters
• Stellar density distribution in the NIR on the Galactic plane at longitudes 15-27 deg. Clues for the Galactic bar ?
• Structure in the First Quadrant of the Galaxy: an Analysis of "TMGS" Star Counts using the "SKY" Model
• VdBH 222: a starburst cluster in the inner Milky Way
• On the shape of the mass-function of dense clumps in the Hi-GAL fields. I. SED determination and global properties of the mass-functions
• Cherenkov Telescope Array sensitivity to the putative millisecond pulsar population responsible for the Galactic center excess
• Infrared dark clouds on the far side of the Galaxy
• WR 120bb and WR 120bc: a pair of WN9h stars with possibly interacting circumstellar shells
• An obscured cluster associated with the HII region RCW173
• H-alpha as a Luminosity Class Diagnostic for K- and M-type Stars
• Dynamical evolution of two associated galactic bars