Near-infrared and Millimeter-wavelength Observations of Mol 160: A Massive Young Protostellar Core

Abstract

We have discovered two compact sources of shocked H2 2.12-micron emission coincident with Mol 160 (IRAS 23385+6053), a massive star-forming core thought to be a precursor to an ultracompact HII region. The 2.12-micron sources lie within 2" (0.05 pc) of a millimeter-wavelength continuum peak where the column density is >= 10e24 cm${}^{-2}$. We estimate that the ratio of molecular hydrogen luminosity to bolometric luminosity is > 0.2%, indicating a high ratio of mechanical to radiant luminosity. CS J=2-1 and HCO${}^{+}$ J=1-0 observations with CARMA indicate that the protostellar molecular core has a peculiar velocity of ~ 2 km s${}^{-1}$ with respect to its parent molecular cloud. We also observed 95 GHz CH3OH J=8$-7 Class I maser emission from several locations within the core. Comparison with previous observations of 44-GHz CH3OH maser emission shows the maser sources have a high mean ratio of 95-GHz to 44-GHz intensity. Our observations strengthen the case that Mol 160 (IRAS 23385+6053) is a rapidly accreting massive protostellar system in a very early phase of its evolution.

47 pages, 8 figures, 2 tables, accepted for publication in ApJ, 7 Dec 2011

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• The SOFIA Massive (SOMA) Star Formation Survey. IV. Isolated Protostars
• The Milky Way Project: What are Yellowballs?
• Investigation of Molecular Cloud Structure around Infrared Bubbles: CARMA Observations of N14, N22, and N74
• MHOs toward HMOs: A Search for Molecular Hydrogen emission-line Objects toward High-Mass Outflows
• Massive Star Formation, Outflows, and Anomalous H2 Emission in Mol 121 (IRAS 20188+3928)
• Possibilities for methanogenic and acetogenic life in molecular cloud