Variable dust emission from Wolf-Rayet stars.
Abstract
An infrared photometric survey of late type Wolf-Rayet stars shows little evidence for secular variation in mass loss or dust formation rates apart from the three known variables: WR 48a, WR 137 (HD 192641) and WR 140 (HD 193793, the prototype). In 1985, WR 140 again brightened sharply in the infrared owing to the formation of circumstellar dust. The relation of this to the previous dust condensation episode strongly supported suggestions that these episodes were periodic (P = 7.9 yr). This leads to confirmation that the system is a binary, and provides a framework for the interpretation of the radio and X-ray variations. Observations of WR 48a and WR 137 show steady fading since their recent dust condensation events, and comparison with earlier photometry suggests a period of about 12 yr for WR 137.
- Publication:
-
Quarterly Journal of the Royal Astronomical Society
- Pub Date:
- September 1987
- Bibcode:
- 1987QJRAS..28..248W
- Keywords:
-
- Cosmic Dust;
- Infrared Spectra;
- Stellar Mass Ejection;
- Variable Stars;
- Wolf-Rayet Stars;
- Exosat Satellite;
- Radio Spectra;
- Secular Variations;
- Spaceborne Astronomy;
- Stellar Luminosity;
- X Ray Spectra;
- Astrophysics