EUVE Phase-Resolved Spectroscopy of V834 Centauri
Abstract
(abridged) The Extreme Ultraviolet Explorer (EUVE) satellite was employed in 1999 February to acquire phase-resolved EUV photometric and spectroscopic observations of the AM Her-type cataclysmic variable V834 Centauri. Although we do not understand the EUV light curves in detail, they are explained qualitatively by a simple model of accretion from a ballistic stream along the field lines of a tilted magnetic dipole centered on the white dwarf. The 75-140 Angstrom EUVE spectra are well described by either a blackbody or a pure-H stellar atmosphere absorbed by a neutral hydrogen column density, but constraints on the size of the EUV emission region and its UV brightness favor the blackbody interpretation with temperature kT ~ 17.6 eV, hydrogen column density NH ~ 7.4x1019 cm-2, fractional emitting area f ~ 10-3, and luminosity Lsoft ~ 7.2x1032 (d/100 pc)2 erg s-1. The ratio of the EUV to X-ray luminosities is Lsoft/Lhard ~ 40, signaling that some mechanism other than irradiation (e.g., blob heating) dominates energy input into the accretion spot.
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