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Session 58 - Future of Antarctic Astrophysics.
Display session, Wednesday, June 10
Atlas Ballroom,

[58.10] AST/RO Observations of [CI] in Galactic H\thinspace II Regions

We present the results of a study of atomic carbon ( ^3P_1\to^3P_0) emission from Southern Hemisphere H \ \scriptstyle II regions using the Antarctic Submillimeter Telescope and Remote Observatory (AST/RO).

One part of our H \ \scriptstyle II region sample consists of 49 compact, relatively isolated members of the Wilson et al. (1970) hydrogen radio recombination line (RRL) emission catalogue. Most [C \ \scriptstyle I \,] spectra of the sample show multiple emission components, and every H \ \scriptstyle II region has associated [C \ \scriptstyle I \,] emission near the RRL velocity. The mean linewidth of these [ C \ \scriptstyle I \,] components is 6.8 \pm 3.0 \, km s^-1; this cannot be explained by thermal broadening and indicates that turbulent broadening is important. RRL-associated [C \ \scriptstyle I \,] emission components are brighter than those not associated with H \ \scriptstyle II regions, which suggests that the [C \ \scriptstyle I \,] intensities are dominated by local heating.

The second part of our sample consists of 11 H \ \scriptstyle II regions from the Caswell and Haynes (1987) radio recombination line catalogue. We have observed fine-structure C^+ (157 \mum) emission using the Long Wavelength Spectrometer (LWS) on board the ISO satellite. We have also observed both CO J=4-3 and [C \ \scriptstyle I \,] emission using AST/RO, and H_91\alpha, H_92\alpha RRLs using the 140-foot radiotelescope at NRAO Greenbank. We discuss the physical properties of the H \ \scriptstyle II regions based on the different tracers of ionized, neutral, and molecular gas in the sample.

This research was supported by the National Science Foundation under a cooperative agreement with the Center for Astrophysical Research in Antarctica (CARA), grant number NSF OPP 89-20223. CARA is a National Science Foundation Science and Technology Center.

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