Ultraviolet Studies of DA White Dwarfs with FUSE
Abstract
Over the course of the Far Ultraviolet Spectroscopic Explorer (FUSE) mission, many DA white dwarfs have been observed either as background sources for local interstellar medium studies or for detailed investigations of white dwarf atmospheres. The FUSE sample provides a rather complete snapshot of the population of DA's with stars as cool as ZZ Ceti stars or as hot as stars that have barely initiated their descent on the white dwarf cooling tracks. Based on this large sample of stars, we present a FUV spectroscopic analysis of DA white dwarfs. With the help of detailed model atmospheres, we determine the effective temperatures and surface gravities of DA white dwarfs by fitting their Lyman line profiles. We also measure or set abundances upper limits of ionic species that are predicted by the radiative levitation theory. We compare our atmospheric parameters to those obtained by fitting the Balmer lines, and critically review our abundances and upper limits in terms of the diffusion theory.
- Publication:
-
American Astronomical Society Meeting Abstracts #213
- Pub Date:
- December 2009
- Bibcode:
- 2009AAS...21360301D