X-Ray Activity as Statistical Age Indicator: The Disk G--K Giants
Abstract
For a sample of late-type disk giant stars, the dependence of coronal emission on age as defined by metallicity and kinematics indicators has been studied. It is found that the mean level of X-ray emission for stars with strong metallic lines and/or small peculiar velocities is larger by about one order of magnitude than the mean level of emission for stars with weak lines and/or high peculiar velocities. Hence, it is suggested that the X-ray activity can be used as a statistical age indicator for late-type giants, as well as the classical metallicity or kinematics indicators. It is found that the spread in metallicity typical of the Galactic disk accounts for less than 50 percent of the observed difference in X-ray emission. To explain the observations it is argued that other effects should be invoked, such as changes in the efficiency of the stellar magnetic dynamo or the influence of metallicity itself on the coronal heating processes.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1992
- DOI:
- 10.1086/171139
- Bibcode:
- 1992ApJ...388..171M
- Keywords:
-
- G Stars;
- Giant Stars;
- K Stars;
- Stellar Activity;
- Stellar Evolution;
- X Ray Stars;
- Color-Magnitude Diagram;
- Emission Spectra;
- Hertzsprung-Russell Diagram;
- Metallicity;
- Stellar Coronas;
- Astrophysics;
- STARS: CORONAE;
- STARS: EVOLUTION;
- STARS: LATE-TYPE;
- X-RAYS: STARS