The Binary Nature of the Barium and CH Stars. III. Orbital Parameters
Abstract
Results are presented from a 10-year program to monitor the velocity variations of Ba II and CH stars, showing that all Ba II and CH stars are binaries. Radial-velocity observations for Ba II and CH binaries are given. Also, the results of orbit calculations and orbital element determinations are analyzed. It is shown that the eccentricities of Ba II star orbits are significantly lower than the eccentricities for a sample of normal G and K giants. In addition, the eccentricities of CH star orbits are significantly lower than those of Ba II stars, suggesting dissipation due to mass exchange, probably from a previous AGB star. The mass functions for Ba II and CH stars indicate that the stars come from samples of binary systems with a small dispersion in mass ratios. If the Ba II and CH stars are assumed to have masses of 1.5 and 0.8 solar mass, respectively, then their companions would have masses near 0.6 solar mass, similar to the values expected for white dwarfs.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 1990
- DOI:
- 10.1086/168573
- Bibcode:
- 1990ApJ...352..709M
- Keywords:
-
- Binary Stars;
- Orbital Elements;
- Red Giant Stars;
- Stellar Composition;
- Stellar Evolution;
- Stellar Orbits;
- Asymptotic Giant Branch Stars;
- Barium;
- Hydrocarbons;
- Astrophysics;
- STARS: BA II;
- STARS: BINARIES;
- STARS: EVOLUTION;
- STARS: LATE-TYPE