NEAR-INFRARED AND MILLIMETER-WAVELENGTH OBSERVATIONS OF Mol 160: A MASSIVE YOUNG PROTOSTELLAR CORE

摘要

We have discovered two compact sources of shocked H2 2.12?μm emission coincident with Mol?160 (IRAS 23385+6053), a massive star-forming core thought to be a precursor to an ultracompact H?II region. The 2.12?μm sources lie within 2'' (0.05?pc) of a millimeter-wavelength continuum peak where the column density is ≥1024?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 the Combined Array for Research in Millimeter-wave Astronomy (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 that 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.