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Wolf Rayet stars in galaxies and the role of binaries and hydrodynamics

Published online by Cambridge University Press:  07 August 2017

André Maeder
André Maeder*
Affiliation:
Geneva Observatory, CH-1290 Sauverny, Switzerland

Abstract

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WR stars obey M-L-·-Teff-R-chemistry relations, which are in general model independent (with the exception of chemistry). The processes of WR formation (stellar winds, hydrodynamical mixing, binary mass transfer etc.) influence, however, the domain of parameters occupied by WR stars. We specifically examine the distribution of luminosities and H-contents of WN stars, which both support heavy mass loss rates, or possibly mixing, in the main sequence and WNL phases. Detailed studies of the number ratios WR/O, WC/WN, WC/WR, etc. are made for galaxies at various metallicities Z which exhibit extremely different WR populations. Good agreement of models and observations is found. It is also shown that the data are better explained if a certain fraction Φ (less than 10%) of the O-stars become WR stars, preferentially of type WNE as a result of Roche lobe overflow (RLOF) in binaries. This result necessarily implies that the fraction of WR stars, owing their existence to RLOF, is variable with Z, being nearly 100% at low Z and much smaller at high Z. We also identify several hydrodynamical developments physically required in stellar models. Among them, we collect the available observational and theoretical arguments supporting an important role of mixing in massive star evolution.

Keywords

stars: Wolf-Rayetclose binariesmass-lossevolutionhydrodynamics
Type
Session V - Stellar winds and massive binary evolution
Information
Symposium - International Astronomical Union , Volume 163: Wolf-Rayet Stars: Binaries, Colliding Winds, Evolution , 1995 , pp. 280 - 290
Copyright
Copyright © Kluwer 1995 

References

Armandoff, T.E., Massey, Ph. 1991, A3 102, 927 Google Scholar
Beech, M., Mitalas, R. 1992, A&A 262, 483 Google Scholar
Conti, P.S., Massey, P. 1989, ApJ 337, 251 Google Scholar
Conti, P.S., Vacca, W.D. 1990, AJ 100, 431 Google Scholar
de Greve, J.P. 1991, in: van der Hucht, K.A. & Hidayat, B. (eds.), Wolf-Rayet Stars and Interrelations with Other Massive Stars in Galaxies, Proc. IAU Symp. No. 143 (Dordrecht: Kluwer), p. 213 Google Scholar
de Greve, J.P., Hellings, P., van den Heuvel, E.P.J. 1988, A&A 189, 74 Google Scholar
de Loore, C. 1982, in: de Loore, C.W.H. & Willis, A.J. (eds.), Wolf-Rayet Stars: Observations, Physics, Evolution, Proc. IAU Symp. No. 99 (Dordrecht: Reidel), p. 343 Google Scholar
de Loore, C., Vanbeveren, D. 1994, A&A in press Google Scholar
Fransson, C., Cassatella, A., Gilmozzi, R., Kirshner, R.P., Panagia, N., Sonneborn, G., Wamsteker, W. 1989, ApJ 336, 429 CrossRefGoogle Scholar
Gies, D.R., Lambert, D.L. 1992, ApJ 387, 673 Google Scholar
Glatzel, W., Kiriakidis, M., Fricke, K.J. 1993, MNRAS 262, L7 Google Scholar
Hamann, W.-R., Koesterke, L, Wessolowski, U. 1993, A&A 274, 397 Google Scholar
Herrero, A., Kudritzki, R.P., Vilchez, J.M., Kunze, D., Butler, K., Haser, S. 1992, A&A 261, 209 Google Scholar
Kiriakidis, M., Fricke, K. J., Glatzel, W. 1993, MNRAS 264, 50 Google Scholar
Langer, N. 1989a, A&A 210, 93 Google Scholar
Langer, N. 1989b, A&A 220, 135 Google Scholar
Langer, N. 1991, A&A 248, 531 Google Scholar
Langer, N., El Eid, M.F., Fricke, K.J. 1985, A&A 145, 179 Google Scholar
Langer, N., Hamann, W.-R., Lennon, M., Najarro, F., Pauldrach, A.W.A, Puls, J. 1994, A&A in press Google Scholar
Maeder, A. 1983, A&A 120, 113 Google Scholar
Maeder, A. 1987, A&A 178, 159 Google Scholar
Maeder, A. 1991, A&A 242, 93 Google Scholar
Maeder, A., Conti, P.S. 1994, Ann. Rev. A&A in press Google Scholar
Maeder, A., Meynet, G. 1994, A&A 287, 803 Google Scholar
Massey, Ph. 1981, ApJ 246, 153 Google Scholar
Meynet, G. 1991, in: de Jager, C. & Nieuwenhuijzen, H. (eds.), Instabilities in Evolved Super- and Hypergiants (Amsterdam: North Holland), p. 173 Google Scholar
Meynet, G., Maeder, A., Schaller, G., Schaerer, D., Charbonnel, C. 1994, A&A Suppl. 103, 97 Google Scholar
Penny, L.R., Gies, D.R., Hartkopf, W.I., Mason, B.D., Turner, N.H. 1993, PASP 105, 588 CrossRefGoogle Scholar
Schaerer, D., Maeder, A. 1992, A&A 263, 129 Google Scholar
Schaller, G. 1992, PhD thesis, University of Geneva Google Scholar
Smith, L.F., Maeder, A. 1989, A&A 211, 71 Google Scholar
Smith, L.F., Maeder, A. 1991, A&A 241, 77 Google Scholar
Smith, L.F., Meynet, G., Mermilliod, J.-C. 1994, A&A bf 287, 835 Google Scholar
Vanbeveren, D. 1991, Space Sci. Rev. 54, 249 Google Scholar
Vanbeveren, D. 1994, Space Sci. Rev. 66, 327 Google Scholar
Vanbeveren, D., de Loore, C. 1993, in: Cassinelli, J.P. & Churchwell, E.B. (eds.), Massive Stars: Their Lives in the Interstellar Medium, ASP. Conf. Ser. 35, 257 Google Scholar
van der Hucht, K.A., Hidayat, B., Admiranto, A.G., Supelli, K.R., Doom, C. 1988, A&A 199, 217 Google Scholar
Venn, K.A. 1993, ApJ 414, 316 Google Scholar
Walborn, N. 1988, in: Nomoto, K. (ed.), Atmospheric Diagnostics of Stellar Evolution, Proc. IAU Coll. No. 108 (Berlin: Springer), p. 70 Google Scholar
Willis, A.J. 1991, in: Michaud, G. & Tutukov, A. (eds.), Evolution of Stars: The Photospheric Abundance Connection, Proc. IAU Symp. No. 145 (Dordrecht: Kluwer), p. 195 Google Scholar
Zahn, J.P. 1992, A&A 265, 115 Google Scholar