ACCRETION PROCESSES IN COSMIC SOURCES: The Atmospheres of Accreting White Dwarfs

A comparison is presented between the physical processes operative in single white dwarfs and the physical processes operative in white dwarfs with donor star companions. The physical properties and accretion physics of the hot accreting components in close interacting binaries is presented. The N/C abundance anomaly seen is ∼10% of cataclysmic variables and the presence of absorption lines due to heavy elements in suprasolar abundance are discussed. A synthetic spectral analysis of the FUSE spectrum of the old nova RR Pic reveals reveals an accretion disk with i = 60°, M(wd) = 1.0M(⊙) and a high accretion rate of 10(−8)M(⊙)/yr. New evidence from the FUSE and IUE spectra of the symbiotic system CQ Dra suggest it is a triple system consisting of a red giant and a cataclysmic variable companion. The hot component in the symbiotic system, RW Hya, consists of a white dwarf with a surface temperature of 160,000 K with log(g) = 6.5 and no evidence of an accretion disk.