Candidate Molecular Outflows from UC HII Regions

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Session 30 -- Star Formation, Molecular Clouds and HII Regions
Display presentation, Tuesday, 31, 1994, 9:20-6:30

[30.11] Candidate Molecular Outflows from UC HII Regions

D.S. Shepherd, E.B. Churchwell (U. Wisc., Madison)

Ultracompact (UC) HII regions surrounding deeply embedded O and B stars represent the earliest stages of massive star formation and evolution. Although much has been learned about the global properties of these active objects, we are far from understanding how massive stars form and how they impact their environments. A key to the early stages of massive star formation during the accretion/outflow phase has been the discovery that several UC HII regions (i.e. G5.89-0.39, DR 21, and W49) are at the center of massive, luminous molecular outflows. To further our understanding of the global properties of massive star evolution during this phase we must identify additional sources that are undergoing bipolar outflow.

To address this issue we have performed a survey of UC HII regions to search for high velocity $^{12}$CO(J = 1 - 0) line wings with the NRAO 12m telescope. Our results are presented here. Most of the sources observed show evidence for some high velocity gas in the wing profiles indicating that these sources are candidates for massive stars with bipolar molecular outflows. Nearly 25$\%$ of the observed sources show extreme high velocity (EHV) wings with full width zero intensity (FWZI) $>$ 100 km~s$^{-1}$ at the 50 mK level.

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