Ultracompact H II Regions in OB Associations

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Session 62 -- Very Young Stars
Display presentation, Thursday, 9:20-4:00, Pauley Room

[62.08] Ultracompact H II Regions in OB Associations

C. D. Garmany (U. Colorado)

Ultracompact H II regions were suggested to be recently formed O-type stars by Mezger over 25 years ago. They represent some of the most luminous objects in the galaxy, and some of the strongest IRAS point sources. Recently, Wood and Churchwell (1989) have demonstrated that the spectral energy distribution from VLA and IRAS data is consistent with these objects being small nebulae produced by O and B stars that are still embedded in their placental clouds and radiating most of their energy in the far IR. A large scale survey of ultracompact H II regions has also been carried out by Wood and Churchwell who showed that these objects can be isolated in an IRAS color-color plot. The galactic distribution of these objects is consistent with their identification as embedded O stars, but no detailed comparisons have been done. I have examined the distribution of these IRAS point sources and compared them with OB associations studied by Garmany and Stencel (1992). The correlation supports the idea of contemporaneous star formation in OB associations.

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