Extremely metal-deficient stars. I - Evolution of 10 solar-mass stars to C-ignition
Abstract
The evolution of 10-solar-mass star models with helium abundance 0.20 and metallicities (Z) of 10 to the minus 8th, 10 to the minus 6th, 10 to the minus 5th, and 0.0004, has been followed from the main sequence phase to carbon ignition. A previous evolution of a Z = 0, 10-solar-mass model has been also extended to C-ignition. In a very metal-poor stellar population, the upper mass limit for degenerate carbon ignition is greater than in more metal-rich stars. This upper mass limit increases by about two solar masses (up to about 9.5 solar masses) if Z decreases from 0.0004 to 10 to the minus 8th by mass. The upper mass limit for C-shell ignition has been found larger than in previous works. All along the studied phases of Z = 0, 10 to the minus 8th, and 10 to the minus 6th, star models never become red giants. The layers surrounding the He cores in stars with Z less than 10 to the minus 6th are sensitively He-enriched, and, as a consequence, an additional amount of He has to be added to the yields derived by bare He-core evolutions.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- February 1984
- DOI:
- 10.1093/mnras/206.4.867
- Bibcode:
- 1984MNRAS.206..867T
- Keywords:
-
- Main Sequence Stars;
- Metallicity;
- Nuclear Reactions;
- Stellar Evolution;
- Stellar Mass;
- Stellar Models;
- Carbon;
- Heavy Elements;
- Helium;
- Hertzsprung-Russell Diagram;
- Hydrogen;
- Ignition;
- Iron;
- Supernovae;
- Astrophysics