Institut für Astronomie und Astrophysik

Abteilung Astronomie

Preprint 03b/98

Improved NLTE Model Atmospheres for the Analysis of Hot Compact Stars

Thomas Rauch

Institut für Astronomie und Astrophysik, Astronomie, Universität Tübingen, Waldhäuser Str. 64, D-72076 Tübingen, Germany

Contribution to the 2nd Oak Ridge Symposium on Atomic & Nuclear Astrophysics, Oak Ridge, TN, USA, 2.-6.12.97

Abstract. Recent developments in observational techniques, NLTE spectral analysis, numerical methods, and the availability of reliable atomic data facilitate to perform precise analyses of hot compact stars. Depending on their high effective temperatures (T_eff), these stars have their flux maxima in the UV - X-ray range and hence, the consideration of metal opacities is of extreme importance for the structure of the whole model atmosphere: Simultaneous fitting of the emergent spectra from the infrared to the (soft) X-ray wavelength range is a general test for the reliability of the investigation on photospheric properties like T_eff, surface gravity g, and chemical composition: Their accurate determination is essential in order to compare with evolutionary, pulsation, and diffusion theory which improves our picture of post-Asymptotic Giant Branch (post-AGB) stellar evolution and provides stringent constraints for these theories.

Paper (229k gzip'ed Postscript including figures)

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Jürgen Barnstedt (barnstedt AT astro.uni-tuebingen.de) Last updated 19-Feb-1998