HEAO-1 observations of X-ray emission from RS CVn systems
Abstract
The HEAO 1 low-energy detectors have observed soft X-ray emission from nine sources which are classified as RS CVn systems. Spectra in the energy range 0.15-2.8 keV have been obtained of two of these, Alpha Aur (Capella) and UX Ari (HD 21242). The spectrum of Capella indicates intense line emission at 0.85 keV which is interpreted as emission from an isothermal solar-abundance plasma at a temperature of (10.5 + or - 2.8) million K. The feature is a blend of principally Fe XVII lines at this energy. However, UX Ari does not display emission at 0.85 keV and, interpreted isothermally, indicates an iron abundance at least a factor 10 below the cosmic value. The continuum temperature is again near 10 million K. The other 7 sources, HR 1099, RS CVn, AR Lac, HK Lac, RW UMa, LX Per, and Sigma Gem, have broadband counting rates consistent with this temperature, and all luminosities are in the range 4 x 10 to the 30th - 10 to the 32nd power erg/s. A common X-ray emission mechanism is developed for these systems which involves a hot corona maintained by extensive flaring activity. Thus RS CVn systems form a new class of low-luminosity soft X-ray sources.
- Publication:
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COSPAR, 21st Plenary Meeting
- Pub Date:
- May 1978
- Bibcode:
- 1978cosp.meetT....C
- Keywords:
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- Astronomical Spectroscopy;
- Binary Stars;
- X Ray Sources;
- X Ray Spectra;
- Chromosphere;
- Emission Spectra;
- Spectral Energy Distribution;
- Stellar Atmospheres;
- Stellar Models;
- Astronomy