Outflow activity in the UCHII region G045.47+0.05

Abstract

Aims. This work aims at investigating the molecular gas in the surroundings of the ultra-compact HII region G045.47+0.05 looking for evidence of molecular outflows.Methods. We carried out observations towards a region of 20×20 centered at RA=19h14m25.6s, dec.=+1109027.600(J2000) using the Atacama Submillimeter Telescope Experiment (ASTE; Chile) in the 12CO J=3?2, 13CO J=3?2, HCO+ J=4?3 and CS J=7?6 lines with an angular resolution of 2200. We complement these observations with public infrared data.Results. We characterize the physical parameters of the molecular clump where G045.47+0.0 is embedded. The detection of the CS J=7?6 line emission in the region reveals that the ultra-compact HII region G045.47+0.0 has not completely disrupted the dense gas where it was born. The HCO+ abundance observed towards G045.47+0.0 suggests the presence of molecular outflow activity in the region. From the analysis of the 12CO J=3?2 transition we report the presence of bipolar molecular outflows with a total mass of about 300 M. We derive a dynamical time (flow?s age) of about 10^5 yr for the outflow gas, in agreement with the presence of an ultra- compact HII region. We identify the source 2MASS 19142564+1109283 asthe massive protostar candidate to drive the molecular outflows. Based on the analysis of its spectral energy distribution we infer that it is an early B-type star of about 15 M. The results of this work support the scenario where the formation of massive stars, at least up to early B-type stars, is similar to that of low mass stars.