Atomic Carbon Observations of Southern Hemisphere H II Regions

May 1999 • 1999ApJ...517..282H

Authors • Huang, Maohai • Bania, T. M. • Bolatto, Alberto • Chamberlin, Richard A. • Ingalls, James G. • Jackson, James M. • Lane, Adair P. • Stark, Antony A. • Wilson, Robert W. • Wright, Gregory A.

Abstract • We report observations of atomic carbon (C I [3P1-->3P0]) for a sample of 49 southern hemisphere H II regions using the Antarctic Submillimeter Telescope and Remote Observatory. The sources are compact and isolated members of the Wilson et al. H109α radio recombination line (RRL) catalog. The fourth Galactic quadrant is well covered by the sample. Atomic carbon emission is detected toward all of the regions, with multiple C I emission components found toward most sources. The RRL velocity is used to identify the C I emission associated with the H II region. We measure the mean velocity difference between the C I and RRL emission to be 0.8+/-2.8 km s-1. Within the measurement errors this is exact agreement in velocity; we conclude that all H II regions have associated C I emission. The mean C I line temperature of these components is 2.4+/-1.8 K, compared with 0.7+/-0.7 K for the C I emission components not associated with the H II region. This suggests that C I intensity is dominated by local heating. The FWHM line width of C I gas associated with H II regions also is marginally greater than that found for unassociated gas (6.7+/-3.0, compared with 4.8+/-2.4 km s-1).


IPAC Authors

Jim Ingalls

Associate Scientist