The Planck submillimeter properties of Galactic high-mass star forming regions: dust temperatures, luminosities, masses and Star Formation Efficiency

Abstract

Massive star formation occurs in the interior of giant molecular clouds (GMC) and proceeds through many stages. In this work, we focus on massive young stellar objects (MYSOs) and Ultra-Compact HII regions (UCHII), where the former are enshrouded in dense envelopes of dust and gas, which the latter have begun dispersing. By selecting a complete sample of MYSOs and UCHII from the Red MSX Source (RMS) survey data base, we combine Planck and IRAS data and build their Spectral Energy Distributions (SEDs). With these, we estimate the physical properties (dust temperatures, mass, luminosity) of the sample. Because the RMS database provides unique solar distances, it also allows investigating the instantaneous Star Formation Efficiency (SFE) as a function of Galactocentric radius. We find that the SFE increase between 2 and 4.5 kpc, where it reaches a peak, likely in correspondence of the accumulation of molecular material at the end of the Galactic bar. It then stays approximately constant up to 9 kpc, after which it linearly declines, in agreement with predictions from extragalactic studies. This behavior suggests the presence of a significant amount of undetected molecular gas at R${}_G$ $>$ 8 kpc. Finally we present diagnostic colors that can be used to identify sites of massive star formation.

Accepted for publication to ApJ

References in corpus (14)

• Trigonometric Parallaxes of Massive Star Forming Regions: VI. Galactic Structure, Fundamental Parameters and Non-Circular Motions
• The UKIDSS Galactic Plane Survey
• Physical properties of molecular clouds for the entire Milky Way disk
• ATLASGAL --- properties of a complete sample of Galactic clumps
• ATLASGAL --- towards a complete sample of massive star forming clumps
• The formation of molecular clouds in spiral galaxies
• The RMS Survey: Radio observations of candidate massive YSOs in the southern hemisphere
• ATLASGAL-selected massive clumps in the inner Galaxy III. Dust Continuum Characterization of an Evolutionary Sample
• Massive 70 micron quiet clumps II: non-thermal motions driven by gravity in massive star formation?
• Star formation scales and efficiency in Galactic spiral arms
• Multi-scale dynamics in star-forming regions: the interplay between gravity and turbulence
• SEDIGISM-ATLASGAL: Dense Gas Fraction and Star Formation Efficiency Across the Galactic Disk
• The Effect of Noise in Dust Emission Maps on the Derivation of Column Density, Temperature and Emissivity Spectral Index
• Galactic Edge Clouds I: Molecular Line Observations and Chemical Modelling of Edge Cloud 2