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Astron. Astrophys. 348, 189-197 (1999)


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Analysis of ultraviolet and extreme-ultraviolet spectra of the DA white dwarf G 191-B2B using self-consistent diffusion models *

S. Dreizler 1 and B. Wolff 2

1 Institut für Astronomie und Astrophysik, Universität Tübingen, D-72076 Tübingen, Germany (dreizler@astro.uni-tuebingen.de)
2 Institut für Theoretische Physik und Astrophysik, Universität Kiel, D-24098 Kiel, Germany (wolff@astrophysik.uni-kiel.de)

Received 2 February 1999 / Accepted 21 May 1999

Abstract

We present a multi-wavelength spectral analysis of the DA white dwarf G 191-B2B. The employed atmospheric models account for gravitational settling and radiative levitation, which are, for the first time, calculated self-consistently with the atmospheric structure. The resulting spectra can reproduce the complete EUVE spectrum and the ultraviolet lines of iron. Some restrictions regarding the UV lines of other elements (C, N, O, Ni), however, still remain. In contrast to homogeneous models, it is not necessary to introduce additional photospheric or interstellar absorbers to account for the high opacity at [FORMULA] Å. Abundance profile changing mechanisms, like mass-loss or accretion, are also not needed.

Key words: stars: abundances – stars: atmospheres – stars: evolution – stars: individual: G 191-B2B – stars: white dwarfs – ultraviolet: stars

* Based on observations made with the EUVE Sattelite and with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555.

Send offprint requests to: S. Dreizler

© European Southern Observatory (ESO) 1999

Online publication: July 16, 1999

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