A study of the radio continuum emission of the giant H II region S 132.
Abstract
Summary. The radio emission of the H ii region St32 is studied using new high resolution data at 0.6 tO GHz and 4.995 GHz obtained with the WSRT and published t.4 GHz and 0.408 GHz lower resolution data. The results indicate that 2/3 of the radio emission originates in features larger than to' in diameter. The total mass and the low electron density of the source indicate that St32 belongs to the class of evolved giant Hii regions. No traces of recent star formation are found in the radio continuum data, even close to a clearly detected ionization front. Several small diameter sources are also found- in the field. Most are probably background non-thermal objects, but one, source t4, is situated just behind an obscuring dust lane. Two shells of radio emission are detected in the nebula, one of which is associated with a WR star and/or an 08.5 star. The ionization balance in the region is discussed and a lack of ionizing stellar flux in the bright part of the nebula is found. The largest discrepancy occurs in explaining the source of ionization for the more extended component. The evolutionary sequence for the observed structures in consistent with the idea that star formation occurs in sequential sub-groups. Key words: H ii region - radio observations high resolution WR stars
- Publication:
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Astronomy and Astrophysics
- Pub Date:
- November 1978
- Bibcode:
- 1978A&A....70..205H
- Keywords:
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- H II Regions:Radio Radiation;
- H II Regions:Star Formation