Extended thermal radio emission from the Galactic plane.
Abstract
A six square degree sample of the MOST southern Galactic plane radio survey at 1=3120, b =00 is presented. In addition to discrete radio sources such as classical H ii regions, supernova remnants and extragalactic background sources, the survey has revealed an abundance of low-surface-brightness extended structure, mostly too faint to have been recognized in earlier radio observations. Comparison between our 0.843-GHz data and IRAS observations suggests that these faint structures are likely to be thermal. The structures may be linked to the extended H ii envelopes that have been postulated to explain both low-frequency spectral turnovers of Galactic supernova remnants and low-frequency radio recombination lines from apparently blank regions of the Galactic plane. They may also represent an intermediate state between classical H ii regions and the warm ionized medium. Key words: ISM: general - H ii regions - ISM: structure - supernova remnants - infrared: ISM: continuum - radio continuum: ISM.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- July 1994
- DOI:
- 10.1093/mnras/269.2.294
- Bibcode:
- 1994MNRAS.269..294W