Metal-Poor Stars. I. Evolution from the Main Sequence to the Giant Branch
Abstract
The evolution of metal-poor stars during early hydrogen-burning phases is described as a function of all composition variables. New Cox-Stewart opacity tables have been used for the pertinent models. Particular attention is paid to (1) the dependence on age and composftion of the turnoff characteristics of derived time-constant loci and (2) the dependence on time and on the metal-abundance parameter Z of interior-structure variables. Turnoff surface temperature is found to be a strong function of Z. It is shown that, on the basis of a comparison with observed turnoff colors alone, the relative ages of stars in I13, M3, M15, and M92 cannot be determined to better than several billion years.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 1970
- DOI:
- 10.1086/150335
- Bibcode:
- 1970ApJ...159..605I