Rotational modulation and flares on RS CVn and BY DRA stars. III. IUEobserations of V711 Tau = (HR 1099), II Peg and AR Lac.
Abstract
The authors present observations of three RS CVn stars, which were obtained over the stellar rotation cycles with the IUE satellite. Emission lines from high-temperature transition regions and chromospheres analogous to those observed in the solar spectrum were observed. However, the stellar line surface fluxes are hundreds of times the solar values. The only visible component of II Peg and both components of V711 Tau and AR Lac appear to be chromospherically active. The emission line fluxes for II Peg and, marginally, for the other two systems were observed to vary in anti-phase with the optical varations at the time of the authors' IUE observations. By comparing the results of two-spot models from Paper I with the variation of UV line flux, the authors find evidence of a close spatial correlation between spot and plage-like features. They interpret these correlations in terms of large spot areas in the stellar photospheres with overlying magnetic loops, which form plages in the outer atmosphere.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- April 1987
- Bibcode:
- 1987A&A...176..267R
- Keywords:
-
- Binary Stars;
- Starspots;
- Stellar Atmospheres;
- Stellar Flares;
- Stellar Rotation;
- Ultraviolet Spectra;
- G Stars;
- Iue;
- K Lines;
- Line Spectra;
- Magnesium;
- Radial Velocity;
- Stellar Activity;
- Astrophysics