Near-infrared and millimeter-wavelength observations of mol 160: A massive young protostellar core

We have discovered two compact sources of shocked H₂ 2.12μm emission coincident with Mol160 (IRAS 23385+6053), a massive star-forming core thought to be a precursor to an ultracompact HII region. The 2.12μm sources lie within 2″ (0.05pc) of a millimeter-wavelength continuum peak where the column density is ≥10²⁴cm^-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 the Combined Array for Research in Millimeter-wave Astronomy (CARMA) indicate that the protostellar molecular core has a peculiar velocity of 2kms^-1 with respect to its parent molecular cloud. We also observed 95GHz CH₃OH J = 8→7 ClassI maser emission from several locations within the core. Comparison with previous observations of 44GHz CH₃OH maser emission shows that the maser sources have a high mean ratio of 95GHz to 44GHz intensity. Our observations strengthen the case that Mol160 (IRAS 23385+6053) is a rapidly accreting massive protostellar system in a very early phase of its evolution.