A New Catalog of Radio Compact H II Regions in the Milky Way
We utilize new VLA Galactic plane catalogs at 5 and 1.4 GHz covering the first Galactic quadrant (350{sup o} {le} l {le} 42{sup o}, |b| {le} 0.4{sup o}) in conjunction with the MSX6C Galactic plane catalog to construct a large sample of ultra-compact H II regions. A radio catalog of this region was first published by Becker et al. (1994), but we have added new observations and re-reduced the data with significantly improved calibration and mosaicing procedures, resulting in a tripling of the number of 5 GHz sources detected. Comparison of the new 5 GHz catalog and the MSX6C Galactic plane catalog resulted in a sample of 687 matches, out of which we estimate only 15 to be chance coincidences. Most of the matches show red MSX colors and a thermal radio spectrum. The scale height of their Galactic latitude distribution is very small (FWHM of 16' or {approx} 40 pc). These properties suggest that the sample is dominated by young ultra-compact H II regions, most of which are previously uncataloged.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15011570
- Report Number(s):
- UCRL-JRNL-207741; TRN: US200507%%553
- Journal Information:
- Astronomical Journal, Vol. 129
- Country of Publication:
- United States
- Language:
- English
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