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Astron. Astrophys. 320, 237-248 (1997)

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Implication of light metals (Li-Ca) on NLTE model atmospheres of compact hot stars

T. and Rauch

Institut für Astronomie und Astrophysik der Universität, D-24098 Kiel, Germany (rauch@astrophysik.uni-kiel.de) Lehrstuhl Astrophysik der Universität, Am Neuen Palais 10, D-14469 Potsdam, Germany

Received 7 August 1996 / Accepted 10 September 1996


We present an investigation about the influence of "light metals", i.e. lithium through calcium (elements 3 - 20), on structure and emergent fluxes of NLTE model atmospheres for hot compact stars (spectral type O with [FORMULA]).

In contrast to models which are composed only of H, He, C, N, and O, the models which include light metals have a strongly reduced EUV and X-ray flux. Thus, for the calculation of realistic fluxes in these wavelength bands, the inclusion of light metal opacities is indispensable.

The H I and He II line profiles in the optical wavelength range, which are commonly used for the determination of photospheric parameters like effective temperature, surface gravity, and He/H abundance ratio, are affected only marginally and only within their line cores. However, in the case of high resolution, high S/N spectra, these effects are detectable and thus, the light metals can not be neglected.

Key words: stars: atmospheres – stars: early-type – stars: general stars: fundamental parameters

Send offprint requests to: T. Rauch

© European Southern Observatory (ESO) 1997

Online publication: July 3, 1998