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

TL;DR

This study presents near-infrared and millimeter observations of Mol 160, revealing it as a rapidly accreting massive protostellar core with shock emission, masers, and high mechanical luminosity, indicating an early stage of massive star formation.

Contribution

It provides new multi-wavelength observational evidence supporting Mol 160 as a young, rapidly accreting massive protostellar core, highlighting shock activity and maser emissions.

Findings

Detection of shocked H2 emission near Mol 160

High ratio of mechanical to radiative luminosity

Presence of 95 GHz and 44 GHz methanol masers

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.