Massive star formation and feedback in W49A: The source of our Galaxy's most luminous water maser outflow - Astrophysics > Solar and Stellar AstrophysicsReport as inadecuate




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Abstract: We present high spatial resolution mid-IR images of the ring of UCHII regionsin W49A obtained at Gemini North, allowing us to identify the driving source ofits powerful H2O maser outflow. These data also confirm our previous reportthat several radio sources in the ring are undetected in the mid-IR becausethey are embedded deep inside the cloud core. We locate the source of the watermaser outflow at the position of the compact mid-IR peak of source G sourceG:IRS1. This IR source is not coincident with any identified compact radiocontinuum source, but is coincident with a hot molecular core, so we proposethat G:IRS1 is a hot core driving an outflow analogous to the wide-anglebipolar outflow in OMC-1. G:IRS1 is at the origin of a larger bipolar cavityand CO outflow. The water maser outflow is orthogonal to the bipolar CO cavity,so the masers probably reside near its waist in the cavity walls. Models of theIR emission require a massive protostar of 45Msun, 3e5Lsun, and an effectiveenvelope accretion rate of 1e-3Msun-yr. Feedback from the central star couldpotentially drive the H2O maser outflow, but it has insufficient radiativemomentum to have driven the large-scale CO outflow, requiring that this massivestar had an active accretion disk over the past 10^4 yr. Combined with thespatialy resolved morphology in IR images, G:IRS1 in W49 provides compellingevidence for a massive protostar that formed by accreting from a disk,accompanied by a bipolar outflow.



Author: Nathan Smith, Barbara A. Whitney, Peter S. Conti, Chris G. De Pree, James M. Jackson

Source: https://arxiv.org/







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