Outflow activity in the UCHII region G045.47+0.05

M. E. ORTEGA; S. PARON; S. CICHOWOLSKI; M. RUBIO; G. DUBNER

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2012 vol. 546 p. 96 - 107

0004-6361

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 2´ × 2´ centered at RA = 19h14m25.6s, Dec = +11°09´27.6´´(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 22´´. 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 there is molecular outflow activity in the region. From the analysis of the 12CO J = 3-2 transition we report bipolar molecular outflows with a total mass of about 300 Msun. We derive a dynamical time (flow´s age) of about 105 yr for the outflow gas, in agreement with the presence of an ultra-compact HII region. We identify the source 2MASS 19142564+1109283 as the 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 Msun. 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.