1997/01/15 by R. D. McClure, Robert D. McClure · 2 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/133882
11 Latex pages plus 4 ps figures, (accepted by PASP) Also available at http://www.hia.nrc.ca/eprint.html
arxiv created 1997/01/15 · openalex publication_date 1997/03/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30
After ∼16 years of radial-velocity observations of a sample of 22 R-type carbon stars, no evidence for binary motion has been detected in any of them. This is surprising considering that approximately 20% of normal late-type giants are spectroscopic binaries, and the fraction is close to 100% in barium, CH, and subgiant/dwarf CH and barium stars. It is suggested, therefore, that a process that has caused the mixing of carbon to the surface of these stars cannot act in a wide binary system. Possibly, the R stars were once all binaries, but with separations that would not allow them to evolve completely up the giant and asymptotic giant branchs without coalescing. This coalescence may be the agent which causes carbon produced in the helium-core flash to be mixed outwards to a region where convection zones can bring it to the surface of the star.