X-ray observations of selected cataclysmic variable stars using the Einstein observatory

Journal Article · Wed Apr 15 04:00:00 EST 1981 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/158836· OSTI ID:6295970

Cordova, F A; Mason, K O; Nelson, J E

X-ray observations of twelve cataclysmic variable stars using the Einstein Observatory are reported. Nine of these stars, representing all subclasses of cataclysmic variables, were detected. Their fluxes range from 2 x 10/sup -13/ to 1 x 10/sup -11/ ergs cm/sup -2/ s/sup -1/ in the energy interval 0.16--4.5 keV. The 2 sigma upper limits for the remaining stars, which include the so-called magnetic rotators DQ Her and V533 Her, are approx.1 x 10/sup -13/ ergs cm/sup -2/ s/sup -1/. The spectra of all the sources detected are relatively hard (kT> or approx. =5 keV). There is no evidence for an ultrasoft emission component (kTapprox.50 eV) such as has been observed from the dwarf novae SS Cyg and U Gem during optical outburst, even though two of the dwarf novae in the sample were in outburst when they were observed. The X-ray and optical fluxes of the objects observed can be understood in terms of differences in mass accretion rate if the accreting stars in these close binary systems possess a weak magnetic field. The X-ray data are also consistent with models of dwarf novae in which only a small portion of the matter transferred from the red star is accreted onto the degenerate dwarf during optical quiescence.

• Research Organization: California Institute of Technology
• OSTI ID: 6295970
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 245:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BINARY STARS
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
ELECTROMAGNETIC RADIATION
EMISSION
ERUPTIVE VARIABLE STARS
IONIZING RADIATIONS
MAGNETIC FIELDS
NOVAE
RADIATION FLUX
RADIATIONS
SPECTRA
STAR ACCRETION
STAR EVOLUTION
STARS
VARIABLE STARS
VISIBLE RADIATION
X RADIATION
X-RAY SPECTRA