The thick helium-burning shell phase and the second blue loop
Abstract
The evolutionary behavior of 18 models undergoing the thick helium-burning shell phase is explored in detail with a full quasi-static evolutionary code, where the ranges spanned are: mass = 3-11 solar masses, Y = 0.20-0.36, and Z = 0.001-0.03. The appearance of the second blue loop is found to be sensitive to the initial mass and composition, as well as to mixing length, the inclusion of semiconvection and convective overshoot, and the treatment of opacity and rotation. Despite this input parameter sensitivity, only three patterns are distinguished for the second blue loop, whose lifetime is about 3-14% that of the first loop.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 1981
- DOI:
- 10.1086/159154
- Bibcode:
- 1981ApJ...248..298B
- Keywords:
-
- Cepheid Variables;
- Helium;
- Late Stars;
- Nuclear Fusion;
- Stellar Evolution;
- Stellar Structure;
- Convective Flow;
- Hertzsprung-Russell Diagram;
- Stellar Atmospheres;
- Stellar Mass;
- Stellar Models;
- Surface Temperature;
- Astrophysics