Heavy element abundances in DA white dwarfs
Abstract
We present a series of systematic abundance measurements for a group of hot DA white dwarfs in the temperature range 20,000-75,000K, based on far-UV spectroscopy with STIS on HST, IUE and FUSE. Using our latest heavy element blanketed non-LTE stellar atmosphere calculations we have addressed the heavy element abundance patterns for the hottest stars for the first time, showing that they are similar to objects like G191-B2B. The abundances observed in the cooler (<50,000K) white dwarfs are something of a mystery. Some of the patterns (e.g. REJ1032) can be explained by self-consistent levitation-diffusion calculations but there is then a serious difficulty in understanding the appearance of the apparently pure H atmospheres. We also report the detection of photospheric HeII in the atmosphere of WD2218+706.
Keywords
Cite
@article{arxiv.astro-ph/0010448,
title = {Heavy element abundances in DA white dwarfs},
author = {M. A. Barstow and M. R. Burleigh and N. P. Bannister and J. B. Holberg and I. Hubeny and F. C. Bruhweiler and R. Napiwotzki},
journal= {arXiv preprint arXiv:astro-ph/0010448},
year = {2007}
}
Comments
6 Pages, to be published in the Proceedings of the 12th European White Dwarf Workshop, Eds. H.L. Shipman and J.L. Provencal, ASP Conference series