The Principal Investigators (PIs) propose to continue with their current NSF funded study of white dwarf stars and the post-hydrogen burning evolution preceding the white dwarf stage. White dwarfs are highly evolved and very dense stars, with masses similar to that of the sun but with radii more like that of the earth. The specific goals of the proposed study are to better understand 1. the structure and chemical abundances of white dwarfs; 2. changes of their abundances with evolution; 3. mass loss and gain, especially for white dwarfs in binary systems (cataclysmic variables); 4. number density of white dwarfs in and mass contribution to the Galactic disk; and 5. origin of these stars as low-mass main sequence stars. Topics such as classical and dwarf novae, accretion disks of white dwarfs, the "hibernation" scenario of the nova outburst, pre- cataclysmic evolution, binary white dwarfs, and a search for halo white dwarfs are part of this investigation. The research will be done through photometry and spectroscopy, with telescopes in both the Northern and Southern Hemispheres.
