Compact H II regions in the Ophiuchus and R Coronae Austrinae dark clouds
The identification is reported of six compact H ii regions in the Ophiuchus dark clouds and two H ii regions in the R CrA dark cloud that were detected using the NRAO interferometer at 2695 MHz. The observed sizes (thetaapprox. =5''-10'') and fluxes (approx.10 mJy) of these sources require that their excitation be supplied by early B stars embedded within the clouds. Three of the H ii regions in Ophiuchus appear to be excited by highly obscured stars that have been detected in recent 2 $mu$ surveys of this cloud; using the radio and infrared results, the ratio of total to selective extinction R=4.1 in the dense regions of the cloud is inferred. Further observations suggest that the density contrast between inner and outer parts of the cloud is at least a factor of 100 and that the total visual extinction through the most dense parts of the cloud A/subv/>100 mag. The implications of these results with regard to the interpretation of infrared, radio recombination line and molecular line observations is discussed. (AIP)
- Research Organization:
- National Radio Astronomy Observatory, Edgemont Road, Charlottesville, VA 22901
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-33-024134
- OSTI ID:
- 4043040
- Journal Information:
- Astrophys. J., Lett., v. 202, no. 3, pp. L125-L128, Journal Name: Astrophys. J., Lett., v. 202, no. 3, pp. L125-L128; ISSN AJLEA
- Country of Publication:
- United States
- Language:
- English
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