The chemical composition of R CrB and XX Cam.
Abstract
The R Coronae Borealis stars R CrB and XX Cam are examined using extensive high-resolution Reticon data. Effective temperatures, values of log g, microturbulent velocities, and C/He values are determined, along with elemental abundances and abundance ratios for a wide range of species, including the light and heavy s-process elements. Helium- and carbon-rich models are employed, as is an appropriate model atmosphere code. The evolutionary history of R CrB stars is discussed in detail. It is concluded that both CNO cycle and 3-alpha processed material must have been mixed into the observable layers. The He core and He shell flashes are suggested as possible triggers for the mixing and for the extensive mass loss required to expose the heavily processed layers.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1982
- DOI:
- 10.1086/160370
- Bibcode:
- 1982ApJ...261..595C
- Keywords:
-
- Abundance;
- Cosmochemistry;
- Nuclear Fusion;
- R Coronae Borealis Stars;
- Stellar Mass Ejection;
- Variable Stars;
- Spectral Line Width;
- Stellar Atmospheres;
- Stellar Evolution;
- Supergiant Stars;
- Astrophysics