X-ray observations of a large sample of cataclysmic variable stars using the Einstein Observatory
Open Access
- 1 February 1984
- journal article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 206 (4) , 879-897
- https://doi.org/10.1093/mnras/206.4.879
Abstract
This paper presents the results of an X-ray survey of 31 known or suspected cataclysmic variables. Eighteen of these close binary systems are detected with inferred luminosities in the 0.1–4.0 keV band of between 1030 and 1032 erg s−1. The majority have relatively hard X-ray spectra (kT > 2keV) irrespective of luminosity state. Of seven dwarf novae observed during optical outbursts only U Gem exhibited enhanced ultrasoft X-ray emission (kT ∼ 10 eV) in addition to weak, hard X-ray emission. Variability of the X-ray flux is observed in many of these stars, on time-scales ranging from tens of seconds to hours. The contribution to the flux from extended X-ray emission is investigated for SU UMa and GK Per. Several possibilities for the origin of the hard X-rays are considered.Keywords
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