A study of the microturbulence in giants in terms of stellar evolution.
Abstract
Results are reported for model-atmosphere analyses of eight Hyades giants and nine field giants performed by the curve-of-growth technique to determine whether microturbulent velocity is correlated with effective temperature, surface gravity, or metal abundance. Differences in microturbulent velocity are found among the program stars, the significance of the scatter in microturbulent velocity is evaluated, and it is shown that microturbulent velocity is not uniform among either the Hyades or the field samples and is not correlated with any atmospheric parameter. An attempt is made to correlate microturbulent velocity with the evolutionary state of the sample stars. The results suggest that stars in the helium core burning phase have low microturbulent velocities relative to red giant-branch stars and that the velocity field in the line-formation region of G-K giants is induced by turbulent motions in the underlying convection zone, presumably by means of overshoot.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- July 1978
- Bibcode:
- 1978A&A....67..311F
- Keywords:
-
- Atmospheric Turbulence;
- Giant Stars;
- Stellar Atmospheres;
- Stellar Evolution;
- G Stars;
- Helium;
- K Stars;
- Photosphere;
- Stellar Spectra;
- Thermodynamic Equilibrium;
- Velocity Distribution;
- Astrophysics;
- Atmospheres:Giants;
- Giants:Turbulence