Stellar model chromospheres. IX. Chromospheric activity in dwarf stars.
Abstract
High-resolution Ca II K line profiles are used to model the upper photospheres and lower chromospheres of eight main-sequence stars ranging in spectral type from F0 to M0 and exhibiting different degrees of chromospheric activity. The model chromospheres are studied as a function of spectral type and activity for stars of similar spectral type in order to obtain evidence of enhanced nonradiative heating in the upper-photospheric models and in the ratio of minimum temperature at the base of the chromosphere to effective temperature, a correlation between activity and temperature in the lower chromospheres, and a correlation of the width at the base of the K-line emission core and at the K2 features with activity. Chromospheric radiative losses are estimated for the modelled stars and other previously analyzed main-sequence stars. The results obtained strengthen the argument that dMe flare stars exhibit fundamentally solar-type activity but on an increased scale.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 1979
- DOI:
- 10.1086/157005
- Bibcode:
- 1979ApJ...229..700K
- Keywords:
-
- Chromosphere;
- Dwarf Stars;
- Emission Spectra;
- K Lines;
- Stellar Atmospheres;
- Stellar Models;
- Calcium;
- Data Correlation;
- Flare Stars;
- Late Stars;
- Line Shape;
- Main Sequence Stars;
- Photosphere;
- Ultraviolet Spectra;
- Astrophysics;
- Chromospheres:Dwarfs;
- Line Profiles:Stellar Chromospheres;
- Stellar Chromospheres:Models