Fine analysis of three R Coronae Borealis stars.
Abstract
Coarse analyses of the R Coronae Borealis stars R CrB, RY Sgr, and XX Cham are rechecked with model-atmosphere techniques in order to obtain reliable values of effective temperatures and gravities. The analyses have been performed with a grid of constant-flux-continuum model atmospheres with varying effective temperature, log g, and helium and carbon abundances. The abundances appear to be the same as for (extreme) helium stars; the hydrogen content is 0.0001 or less, carbon is the most abundant element after helium, the metals have approximately solar abundances. The positions in the (gravity, temperature)-plane of three analyzed objects match computed tracks of (extreme) helium stars. From this, the masses and luminosities of R CrB stars can be inferred. The conclusion is drawn that the R CrB stars are cool members of the class of (extreme) helium stars. Their evolution is discussed.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- November 1975
- Bibcode:
- 1975A&A....44..383S
- Keywords:
-
- R Coronae Borealis Stars;
- Solar Corona;
- Stellar Atmospheres;
- Stellar Evolution;
- Abundance;
- Atmospheric Models;
- Atmospheric Temperature;
- Stellar Gravitation;
- Stellar Luminosity;
- Stellar Mass;
- Astrophysics