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| Paper: |
Stellar Ages Using the Chromospheric Activity of Field Binary Stars |
| Volume: |
154, Cool Stars, Stellar Systems and the Sun: Tenth Cambridge Workshop |
| Page: |
1235 |
| Authors: |
Donahue, Robert A. |
| Abstract: |
Ages for the components of binary stars are calculated from measurements of their chromospheric activity using the HK spectrophotometer at Mount Wilson Observatory. Binaries are useful for age calibration because bright open clusters spanning the entire solar Main Sequence lifetime are not readily available, and also because age determinations using moving groups are comparatively uncertain owing to the problem of accurately establishing moving group membership. On the other hand, hundreds of double stars where both components are lower main-sequence stars are reachable with modest-aperture telescopes. Observed age discrepancies within a binary system are interpreted as arising from variability in each star's chromospheric activity, typically due to rotation, activity cycles, or longer-term (extra-cyclic) variability. Relying upon the assumption that the stars in each binary are truly co-eval, the measured age discrepancy sets an estimate for the expected uncertainties in age similarly determined from the chromospheric activity for single field stars. For a sample containing both young and old stars, age discrepancies between two binary components is usually under ~0.5 Gyr. For binaries older than 2 Gyr, the age discrepancy is typically under 1.0 Gyr. Large age discrepancies may indicate that the less-active component is in a Maunder minimum state. |
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