The Distant Future of Solar Activity: A Case Study of beta Hydri. I. Stellar Evolution, Lithium Abundance, and Photospheric Structure
Abstract
A detailed comparison of the current sun (G2 V) with the very old solar-type star Beta Hyi (G2 IV) is presented in order to study the postmain-sequence evolution of stellar activity and of nonthermal processes in solar-type atmospheres. Special attention is given to general stellar properties and the deeper atmosphere of Beta Hyi. A critical review of data from various sources is presented, and the age of Beta Hyi is determined from evolutionary models to 9.5 +/- 0.8 Gyr. The relatively high lithium abundance may be a signature of the early subgiant stage, when lithium that once diffused to beneath the main-sequence convection zone is dredged up to the surface as the convection zone deepens. Numerical simulations of the 3D photospheric hydrodynamics show typical granules to be significantly larger (a factor of about 5) than solar ones.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 1993
- DOI:
- 10.1086/172210
- Bibcode:
- 1993ApJ...403..385D
- Keywords:
-
- Abundance;
- Late Stars;
- Lithium;
- Photosphere;
- Solar Activity;
- Stellar Evolution;
- Metallicity;
- Stellar Atmospheres;
- Stellar Envelopes;
- Stellar Magnetic Fields;
- Stellar Models;
- Stellar Oscillations;
- Astrophysics;
- STARS: ABUNDANCES;
- STARS: ATMOSPHERES;
- STARS: EVOLUTION;
- STARS: INDIVIDUAL CONSTELLATION NAME: BETA HYDRI;
- SUN: ACTIVITY