Oxygen-enhanced Models for Globular Cluster Stars. III. Horizontal-Branch Sequences
Abstract
A large grid of horizontal-branch (HB) evolutionary sequences which have been calculated with core expansion and semiconvection and with enhanced oxygen composition are presented and described. Tracks for 10 different metallicities are computed; they range from (Fe/H) = -0.47 to -2.26 and comprise a total of 115 sequences. The evolution is traced from the zero-age horizontal-branch (ZAHB) to the lower AGB at a point where log L/solar luminosity = 2.25. All of the sequences are illustrated on both the theoretical H-R diagram and on the B, V color-magnitude diagram. A complete set of tables for the ZAHB models and a representative sample of tabulations of the track parameters are provided. The phenomena which control HB evolution morphology, and existing certainties in theoretical HB models are discussed.
- Publication:
-
The Astrophysical Journal Supplement Series
- Pub Date:
- July 1992
- DOI:
- 10.1086/191691
- Bibcode:
- 1992ApJS...81..221D
- Keywords:
-
- Globular Clusters;
- Oxygen;
- Stellar Evolution;
- Stellar Models;
- Asymptotic Giant Branch Stars;
- Color-Magnitude Diagram;
- Stellar Composition;
- Stellar Cores;
- Stellar Luminosity;
- Astrophysics;
- GALAXY: GLOBULAR CLUSTERS: GENERAL;
- STARS: HORIZONTAL-BRANCH;
- STARS: INTERIORS