Stellar surface phenomena: a spectroscopic study of the RS Canum Venaticorum binaries
High resolution observations are reported of the Ca II H and K and H..cap alpha.. regions in a selection of twenty-five RS CVn and related Ca II emission objects. The RS CVn stars were found to have Ca II H and K and H..cap alpha.. line surface fluxes and chromospheric loss rates over an order of magnitude larger than standard stars for their respective spectral types and luminosity classes. In the short-period systems, these line surface fluxes and chromospheric loss rates were found to be well correlated with the fraction of the Roche lobe filled by the active star in the system and the separation between the stars. The H..cap alpha.. profiles of all of the RS CVn systems were found to be filled in by the presence of an overlying emission at all epochs; the profiles of several systems were found to be variable. Combining results of the Ca II and H..cap alpha.. observations, the chromospheric temperature structure in the lower chromosphere was mapped. The RS CVn stars were found to have steeper than normal chromospheric temperature gradients, in agreement with the predictions of the chromospheric models of Linksy and his collaborators. Several systems were also found which showed Ca II H and K emission but not H..cap alpha.. emission.
- Research Organization:
- Toledo Univ., OH (USA)
- OSTI ID:
- 5740405
- Country of Publication:
- United States
- Language:
- English
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