Modelling Alkali Line Absorption and Molecular Bands in Cool DAZs

Details Modelling Alkali Line Absorption and Molecular Bands in Cool DAZs Modelling Alkali Line Absorption and Molecular Bands in Cool DAZs

2005-01-05

arxiv.org/abs/astro-ph/0501077v1

Astronomy and Astrophysics

Astrophysics

to appear in: Proceedings of the 14th European Workshop on White Dwarfs, http://www.astrophysik.uni-kiel.de/~eurowd/ -- ASP Co

Scientific paper

Two peculiar stars showing an apparent extremely broadened and strong NaI D absorption have been discovered in surveys for cool white dwarfs by Oppenheimer et al. (2001) and Harris et al. (SDSS, 2003). We discuss the nature of these objects using PHOENIX atmosphere models for metal-poor brown dwarfs/very low mass stars, and new white dwarf LTE and NLTE models for hydrogen- and helium-dominated atmospheres with metals. These include complete molecular formation in chemical equilibrium and a model for the alkali resonance line broadening based on the damping profiles of Allard et al. (2003), as well as new molecular line opacities for metal hydrides. First results of our calculations indicate good agreement with a hydrogen-dominated WD atmosphere with a Na abundance roughly consistent with a state of high accretion. We analyse deviations of the abundances of Na, K, Mg and Ca from the cosmic pattern and comment on implications of these results for standard accretion scenarios.

Affiliated with

Also associated with

No associations

Rating

Modelling Alkali Line Absorption and Molecular Bands in Cool DAZs does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Modelling Alkali Line Absorption and Molecular Bands in Cool DAZs, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Modelling Alkali Line Absorption and Molecular Bands in Cool DAZs will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-531642