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Modelling and quantitative analyses of Wolf-Rayet spectra: recent progress and results

Published online by Cambridge University Press:  25 May 2016

Wolf-Rainer Hamann ,
Lars Koesterke  and
Götz Gräfener
Wolf-Rainer Hamann
Affiliation:
Universität Potsdam, Germany
Lars Koesterke
Affiliation:
Universität Potsdam, Germany
Götz Gräfener
Affiliation:
Universität Potsdam, Germany

Abstract

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The quantitative analysis of Wolf-Rayet type spectra requires non-LTE models for expanding atmospheres which have been developed in the last decade. Idealizing assumptions of the so-called standard model are spherical symmetry, homogeneity and stationarity. While the first generations of models were restricted to simple atoms (helium, hydrogen), we now apply more advanced calculations which account for complex model atoms (nitrogen, carbon, oxygen). The re-analysis of the Galactic WN sample from the nitrogen lines led to a substantial revision of the stellar parameters, as far as the WNE-w subclass is concerned. Wind inhomogeneity ('clumping') has been accounted for in a first-order approximation. The degree of clumping is derived from the electron-scattering wings of strong lines. With clumped models, considerably lower mass-loss rates (by a factor two or more) are obtained, while other empirical parameters are not affected significantly. An overview is given about the fundamental parameters of Wolf-Rayet stars as obtained from spectral analyses, including new results on WN stars in the LMC.

Type
Part 2. Models for single star evolution of massive stars: wind + atmosphere + interior
Information
Symposium - International Astronomical Union , Volume 193: Wolf-Rayet Phenomena in Massive Stars and Starburst Galaxies , 1999 , pp. 138 - 146
Copyright
Copyright © Astronomical Society of the Pacific 1999 

References

Crowther, P.A., Smith, L.J. 1997, A&A 320, 500 Google Scholar
Gräfener, G., Hamann, W.-R., Hillier, D.J., Koesterke, L. 1998, A&A 329, 190 Google Scholar
Hamann, W.-R., Koesterke, L. 1998a, A&A 333, 251 Google Scholar
Hamann, W.-R., Koesterke, L. 1998b, A&A 335, 1003 Google Scholar
Herrero, A., Kudritzki, R.P., Víilchez, J.M., Kunze, D., Butler, K., Haser, S. 1992, A&A 261, 209 Google Scholar
Hillier, D.J. 1984, ApJ 280, 744 Google Scholar
Hummer, D.G. 1962, MNRAS 125, 21 Google Scholar
Langer, N., Hamann, W.-R., Lennon, M., Najarro, F., Pauldrach, A.W.A., Puls, J. 1994, A&A 290, 819 Google Scholar
Lucy, L.B., Abbott, D.C. 1993, ApJ 405, 738 Google Scholar
Schaller, G., Schaerer, D., Meynet, G., Maeder, A. 1992, A&AS 96, 269 Google Scholar
Schmutz, W. 1995, in: van der Hucht, K.A. & Williams, P.M. (eds.), Wolf-Rayet Stars: Binaries, Colliding Winds, Evolution Proc. IAU Symp. No. 163 (Dordrecht: Kluwer), p. 127 Google Scholar
Schmutz, W. 1997, A&A 321, 268 Google Scholar
Schmutz, W., Hamann, W.-R., Wessolowski, U. 1989, A&A 210, 236 Google Scholar