Wolf-Rayet stars and circumstellar matter.
Abstract
The paper discusses the masses of Wolf-Rayet (WR) stars, their frequency, their tendencies toward forming binary and multiple systems, and the role of WR stars in the chemical evolution of the interstellar medium. The relative importance of He(plus) in the atmosphere of WR stars is demonstrated on the basis of data on the fluxes of Pickering lines of He II as a function of the quantum number of the upper level of the transition. The high He abundance suggests that WR stars are probably pure helium stars with carbon or heavier element cores. The WR stars contribute to the chemical evolution of the interstellar medium, originating from massive stars which must return most of their material to the IS medium. Three kinds of mass losses from WR stars are characterized. In the WR phase, the high-speed mass ejection has the interesting effect of forming ring nebulae of a filamentary nature. Maintenance of the filaments is briefly discussed.
- Publication:
-
Memorie della Societa Astronomica Italiana
- Pub Date:
- May 1974
- Bibcode:
- 1974MmSAI..45..367S
- Keywords:
-
- Binary Stars;
- Hot Stars;
- Interstellar Matter;
- Stellar Evolution;
- Stellar Mass;
- Wolf-Rayet Stars;
- Chemical Composition;
- Galactic Radiation;
- Helium;
- Star Clusters;
- Stellar Mass Ejection;
- Astrophysics