A Possible case of Protostellar Collapse Triggered by a Small HII region

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Date/Time:Friday, 28 Sep 2012 from 4:10 pm to 5:00 pm
Location:Room 3
Contact:Massimo Marengo
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Seminar by Sung-ju Kang, ISU Astronomy Graduate Student

In this talk, I will present an analysis of HCO+(J=3-2) and H13CO+(J=3-2) observations of the massive (M ~ 20Msun) submm/IR source IRAS 01202+6133 located on the periphery of the HII region KR 120 (SH 2-187). The HCO+ line profile has a classical blue-asymmetric shape with the optically thin H13CO+ line peaking at the position expected HCO+ line arises from a combination of self-absorption and infall motion. We have modified existing analytic radiative transfer models to allow for the fitting of submm/mm line profiles that have both self-absorption features and optically thin wings and applied these models to out HCO+ spectrum of IRAS 01202+6133. We conclude that it is a young Class I YSO with a substantial envelop undergoing slow infall and having some outflow motions. The young age og the HII region rules out a "Collect and Collapse" scenario. While we cannot eliminate the possibility that IRAS 01202+6133 formed spontaneously at its current location, considering its early evolutionary state and its proximity to the HII region we think that the formation of IRAS 01202+6133 was triggered by the expansion of KR 120 (SH 2-187).