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Session 6 - HII Regions & Massive Star Formation.
Display session, Wednesday, January 07
Exhibit Hall,
As part of a program to study the early stages of formation of high mass stars, we are studying ultra-compact HII regions (UC HIIs), their associated hot cores, and possible precursors. We have begun a multi-wavelength study of these regions to determine the relative distributions of the dust, molecules, and ionized gas, and the evolution of the gas distribution during the formation of high mass stars. We use molecular tracers, such as ^13CO, C^18O, and CH_3CN, to determine the properties of these star forming regions before, during, and after the central star heats the surrounding material.
This work presents observations from the BIMA interferometer at \nu = 28.5 and 34.3 GHz and \nu = 109 GHz of three UC HIIs, G34.26+0.15, G33.92+0.11, G11.94-0.62, and one possible precursor, IRAS 18511+0146. G34.26+0.15 is known to have an associated hot core. We have observed all four sources in continuum emission at \nu = 28.5 and 34.3 GHz to determine the spectral index of the free-free emission, and at \nu = 109 GHz to study dust continuum emission. The spectral index for both the free-free and dust emission for the three ultra-compact HII regions will be presented, as well as the properties of the molecular emission seen toward the four sources.
