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NLTE Analysis of the Wolf-Rayet Star HD193077 (WN5+abs)

Published online by Cambridge University Press:  12 April 2016

W. Schmutz ,
W.-R. Hamann  and
U. Wessolowski
W. Schmutz
Affiliation:
Institut für Theoretische Physikund Sternwarte derUniversität KielOlshausenstrasse, D-2300 Kiel l, Federal Republic of Germany
W.-R. Hamann
Affiliation:
Institut für Theoretische Physikund Sternwarte derUniversität KielOlshausenstrasse, D-2300 Kiel l, Federal Republic of Germany
U. Wessolowski
Affiliation:
Institut für Theoretische Physikund Sternwarte derUniversität KielOlshausenstrasse, D-2300 Kiel l, Federal Republic of Germany

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A model atmosphere code that accounts for the special physical conditions in Wolf-Rayet atmospheres (Hamann and Schmutz, 1986; Wessolowski et al., 1987) is used to analyse the spectrum of the Wolf-Rayet star HD193077 (WN5+abs). The stellar parameters are determined such that the profiles of the helium lines He I λλ4471, 5876, He II λ5412, and the absolute visual magnitude are reproduced.

In order to estimate the systematic errors introduced by the model assumptions, we perform some test calculations. Instead of the velocity-law exponent of ß=1, another fit is obtained with ß=0.5 (Fig. 1). This fit yields an effective temperature of about 3000K higher than with ß=1. In order to simulate the effect of the suspected hydrogen content, a further fit (Fig. 2) is made when one free electron per helium atom is added artificially. This has only marginal influence on the derived temperature (+100K). Thus, we conclude that our model assumptions may introduce a systematic error of the order of 5000K.

Type
Part II. Mass-Losing Stars in Different Stages of Evolution
Information
International Astronomical Union Colloquium , Volume 108: Atmospherics Diagnostics of Stellar Evolution: Chemical Peculiarity, Mass Loss, and Explosion , 1988 , pp. 143 - 144
Copyright
Copyright © Springer-Verlag 1988

References

Maeder, A.: 1987, Astron. Astrophys. 178, 159 Google Scholar
Hamann, W.-R., Schmutz, W.: 1986, Astron. Astrophys. 174, 173 Google Scholar
Wessolowski, U., Schmutz, W., Hamann, W.-R.: 1987, Astron. Astrophys. (in press)Google Scholar