White Dwarf Colors in Low Accretion Rate Binaries

Our recent theoretical work (Townsley and Bildsten 2002) on the thermal state of white dwarfs (WDs) in low mass transfer rate binaries allows us to predict the broadband colors of the binary from those of the WD and companion when the disk is dim. The results based on standard CV evolution are presented h ere. These will aid the discovery of such objects in field surveys and proper-motion selected globular cluster surveys with HST; especially for the largely unexplored post period minim um Cataclysmic Variables (CVs) with the lowest accretion rates and degenerate companions. We have also calculated the fraction of time that the WD resides in the ZZ Ceti instability strip thus clarifying that we expect many accreting WDs to exhibit non-radial oscillations. The study of these will provide new insights into the rotational and thermal structure of an actively accreting WD.