Outer atmospheres of cool stars. V. IUE observations of Capella: the rotation-activity connection.
Abstract
UV spectra of Capella (G6 III + F9 III) obtained with the IUE are analyzed. High-resolution emission-line profiles taken near the elongation at phase 78 days suggest that virtually all of the emission in transition-region lines and most of the emission in chromospheric lines comes from the late-F secondary of the system. It is suggested that the origin of the extraordinary activity levels on these otherwise very similar stars can be traced to the one property that is obviously different, i.e., rotation. The Capella primary is a normal sharp-line slow rotating giant, whereas the secondary has broader lines and is a rapid rotator for a late-type giant.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1980
- DOI:
- 10.1086/158341
- Bibcode:
- 1980ApJ...241..279A
- Keywords:
-
- Cool Stars;
- Late Stars;
- Stellar Atmospheres;
- Stellar Rotation;
- Stellar Spectra;
- Stellar Temperature;
- Ultraviolet Astronomy;
- Chromosphere;
- Iue;
- Stellar Magnetic Fields;
- Stellar Spectrophotometry;
- Stellar Winds;
- Ultraviolet Spectra;
- X Ray Astronomy;
- Astrophysics;
- Atmospheres:Cool Stars;
- Late-Type Stars:Rotation;
- Spectroscopic Binaries:UV Spectra