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arXiv 1208.5380astro-ph.GA
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UCHII区域G045中的流出活性.47+0.05

Outflowing activity in the UCHII region G045.47+0.05

M. E. Ortega, S. Paron, S. Cichowolski, M. Rubio, G. Dubner

摘要:

目标。本工作旨在研究超致密HII区G045.47+0.05周围的分子气体,寻找分子外流的证据。方法.我们对一个2弧分× 2弧分的区域进行了观测,中心位置为RA= 19h14m25.6s,dec.= 11度09米27.6秒(J2000),使用阿塔卡马亚毫米望远镜实验(ASTE;智利),在12 CO J = 3 -2,13 CO J=3-2,HCO+ J=4-3和CS J=7-6线,角分辨率为22角秒。我们用公共红外数据补充了这些观测结果。结果我们表征了G045.47+0.0嵌入的分子团簇的物理参数。在该区域中的CS J=7-6线发射的检测表明,超紧凑的HII区域G045.47+0.0还没有完全破坏它出生的致密气体。在G045.47+0.0方向观察到的HCO+丰度表明该区域存在分子流出活性。从12 CO J=3-2过渡的分析,我们报告的双极分子外流的存在下,总质量约300太阳质量。我们推导出外流气体的动力学时间(流的年龄)约为10^5年,与超致密HII区的存在相一致。我们确定源2 MASS 19142564+1109283作为驱动分子外流的大质量原恒星候选者。根据对它的光谱能量分布的分析,我们推断它是一颗大约15个太阳质量的早期B型星。这项工作的结果支持了这样的假设,即大质量恒星的形成,至少在早期的B型恒星中,与低质量恒星的形成相似。

英文摘要:

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 arcmin x 2 arcmin centered at RA=19h 14m 25.6s, dec.= 11deg 09m 27.6s (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 arcsec. 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 solar masses . 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 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 solar masses. 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.

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