The Asymptotic Giant Branch Evolution of 1.0--3.0 Msun Stars as a Function of Mass and Composition
Abstract
Evolutionary calculations are presented for 1.0-3.0 solar mass stellar models covering the abundances Z = 0.001, 0.01, and 0.02 with Y = 0.20 and 0.30. Calculations are begun on either the zero-age main sequence or the zero-age horizontal branch, as appropriate, and include semiconvection in a simple but effective manner. The existence of convective pulses for larger masses is verified. The evolution is continued through to the thermally pulsing Asymptotic Giant Branch star. The core masses at the first pulse are found to be larger than previously estimated for masses of no more than two solar masses and smaller than estimated for masses between 2-3 solar masses. It is predicted that many stars in this mass range, especially those of lower metallicity, should begin dredging carbon to their surfaces from the first pulse. Some models have had their evolution continued until the thermal pulses reach full amplitude, enabling the derivation of a core mass-luminosity relation for this mass and abundance range. None of these models experience the third dredge-up, but this is entirely due to using alpha = 1.0. Comparison with some individual C stars shows that the models presented agree quite well with the observations, provided alpha is about 1.5.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 1986
- DOI:
- 10.1086/164810
- Bibcode:
- 1986ApJ...311..708L
- Keywords:
-
- Asymptotic Giant Branch Stars;
- Giant Stars;
- Horizontal Branch Stars;
- Stellar Composition;
- Stellar Evolution;
- Stellar Mass;
- Stellar Models;
- Carbon Stars;
- Main Sequence Stars;
- Mass To Light Ratios;
- Stellar Cores;
- Stellar Interiors;
- Astrophysics;
- CLUSTERS: GLOBULAR;
- CONVECTION;
- STARS: EVOLUTION;
- STARS: INTERIORS