Volume 546, October 2012
|Number of page(s)||12|
|Section||Interstellar and circumstellar matter|
|Published online||11 October 2012|
Outflow activity in the UCHII region G045.47+0.05
Instituto de Astronomía y Física del Espacio (IAFE),
CC 67, Suc. 28,
2 FADU – Universidad de Buenos Aires, Argentina
3 Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
Received: 17 April 2012
Accepted: 2 August 2012
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 M⊙. 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 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.
Key words: stars: formation / ISM: jets and outflows / ISM: molecules
© ESO, 2012
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