X-Ray Spectra of Cataclysmic Variables from the Einstein Observatory
Abstract
X-ray spectral parameters of 32 cataclysmic variables observed with the Einstein imaging proportional counter are determined by fitting an optically thin thermal bremsstrahlung spectrum to the final reprocessed version of the raw data. Most of the stars show temperatures in the range 1-5 keV, while a few exhibit harder spectra with temperatures in excess of 10 keV. Estimated 0.1-3.5 keV luminosities are generally in the range 10 exp 30-32 ergs/s. The results are consistent with the X-rays originating in a disk/white dwarf boundary layer of nonmagnetic systems, or in a hot, postshock region in the accretion column of DQ Her stars. The contribution of the companion to the X-ray luminosity from the companion's corona is negligible, as the luminosities found are well above the upper limits recently determined for the X-ray luminosities of late-type main-sequence stars. From the unusually high column densities found in a few objects, it is inferred that the absorption occurs in the system itself, and very likely within the Roche lobe of the primary.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 1991
- DOI:
- 10.1086/170716
- Bibcode:
- 1991ApJ...382..290E
- Keywords:
-
- Astronomical Observatories;
- Bremsstrahlung;
- Cataclysmic Variables;
- Proportional Counters;
- X Ray Spectra;
- Energy Spectra;
- Late Stars;
- Stellar Coronas;
- Stellar Luminosity;
- Stellar Temperature;
- Astrophysics;
- STARS: ACCRETION;
- STARS: BINARIES;
- STARS: DWARF NOVAE;
- STARS: X-RAYS