B and A type stars with unexpectedly large colour excesses at IRAS wavelengths. (original) (raw)
NASA/ADS
Abstract
The authors present IRAS observations at 12, 25, 60 and 100 μm of 18 bright stars of spectral type A, 6 of spectral type B, with strongly deviating IR fluxes at those wavelengths. Eight of these stars were already discussed in previous studies. Tables with the IRAS magnitudes, the derived colour excesses and some stellar parameters are presented. For each star the reliability of the observations is discussed. The excess IR fluxes are interpreted either in terms of thermal radiation from circumstellar dust, or in terms of free-free radiation from hot, ionized, circumstellar gas. Dust temperatures are typically in the range between 60 and 130K. Three B-type stars, HR 2501, φ Sgr and HR 7739, were found to be candidates for Be stars.
Publication:
Astronomy and Astrophysics
Pub Date:
July 1987
Bibcode:
Keywords:
- A Stars;
- B Stars;
- Infrared Photometry;
- Infrared Stars;
- Stellar Envelopes;
- Cosmic Dust;
- Cosmic Gases;
- Infrared Astronomy Satellite;
- Stellar Temperature;
- Astrophysics