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

  • W. Schmutz (a1), W.-R. Hamann (a1) and U. Wessolowski (a1)

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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.

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References

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

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

  • W. Schmutz (a1), W.-R. Hamann (a1) and U. Wessolowski (a1)

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