EUVE Phase-Resolved Spectroscopy of V834 Centauri
Abstract
Description
(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 N_H ~ 7.4x10^{19} cm^{-2}, fractional emitting area f ~ 10^{-3}, and luminosity L_soft ~ 7.2x10^{32} (d/100 pc)^2 erg s^{-1}. The ratio of the EUV to X-ray luminosities is L_soft/L_hard ~ 40, signaling that some mechanism other than irradiation (e.g., blob heating) dominates energy input into the accretion spot.
23 pages including 1 table and 9 encapsulated postscript figures; LaTeX format, uses aastex.cls; accepted on 2002 June 17 for publication in The Astrophysical Journal
23 pages including 1 table and 9 encapsulated postscript figures; LaTeX format, uses aastex.cls; accepted on 2002 June 17 for publication in The Astrophysical Journal