Early-type stars in OB associations in the infrared. I. Extinction lawand IR excesses.
Abstract
Observations have been made of 82 early-type stars of OB associations in the infrared (JHKLM). The law of interstellar extinction is investigated. The empirical reddening curve (with R = 3.13) is found to be in close agreement with van de Hulst's (1949) theoretical curve No. 15. This law is generally valid for the OB associations considered. The measured infrared magnitudes were dereddened with this extinction law, and compared with the prediction of model atmospheres. Significant infrared excesses due to circumstellar free-free radiation are found for a large number of stars. The strongest IR excess (about 0.5 mag in M) is found for the Of-type stars HD 108, HD 151804, and HD 152408. In late B supergiants no significant excess radiation is detectable. However, the very luminous hypergiants HD 168607 and HD 168625 do show excess radiation of about 0.2 mag in M.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- March 1984
- Bibcode:
- 1984A&A...132..151L
- Keywords:
-
- B Stars;
- Early Stars;
- Infrared Stars;
- Interstellar Extinction;
- O Stars;
- Stellar Color;
- Infrared Astronomy;
- Southern Hemisphere;
- Stellar Luminosity;
- Supergiant Stars;
- Astrophysics