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Preprint 18/02

Stratified NLTE model atmospheres for hot stars

Stefan Dreizler (1) and Sonja L. Schuh (1)

(1) Institut für Astronomie und Astrophysik, Astronomie, Universität Tübingen, Sand 1, D-72076 Tübingen, Germany

To appear in: Modelling of Stellar Atmospheres, IAU Symposium, Vol. xxx, N. E. Piskunov, W. W. Weiss, D. F. Gray, eds.

Abstract. In most stellar atmosphere models, a homogeneous chemical composition is assumed, which is a good approximation for many stars. With the absence of convection and mass loss, however, gravitational settling can produce a chemical stratification gradient. Typical examples are white dwarfs. In hot stars this diffusion process is modified by the radiative acceleration, resulting in levitation of ions with large radiative cross sections. The status of our program for self-consistent stratified non-LTE model atmospheres is presented.

Key words: -

Paper (114k gzip'ed Postscript including figures)

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