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New models of massive and Wolf-Rayet stars with mass loss and rotation

Published online by Cambridge University Press:  25 May 2016

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

Abstract

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We give results of models of massive stars which have a detailed physical treatment of rotation, including structural equations for shellular rotation, new treatments of shears in differentially rotating stars and of meridional circulation, together with mass loss rates depending on rotation. For a 20 M⊙ star, He- and N-enrichments at the stellar surface already occur during the MS phase for moderately low rotational velocities, thus most supergiants are enriched in helium and nitrogen. A long B- and A-supergiant phase results from rotational mixing, with some primary nitrogen formed at this stage. For the most massive stars, rotation makes the star to enter the WR stage during the MS phase thus avoiding the LBV and red supergiant stage.

The WR life-times are considerably increased by rotation and the minimum mass for forming WR stars is lowered. Interestingly enough, the increase of the WN life-time is larger than for WC stars, so that rotation leads to a decrease of the WC/WN number ratio. Also, the fraction of transition WN/WC stars is much larger at higher rotation.

Finally, on the basis of clusters in the SMC, in the LMC and towards the galactic interior and exterior, we show that for clusters with ages between about 1 and 3 x 107 yr the fraction of Be stars with respect to normal B stars is larger at lower metallicities. This may suggest a higher rotation at lower metallicities for massive stars, due to a different history of star formation.

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. 177 - 186
Copyright
Copyright © Astronomical Society of the Pacific 1999 

References

Conti, P.S., Massey, P. 1989, ApJ 337, 251 CrossRefGoogle Scholar
Feast, M.W. 1972, MNRAS 159,113 Google Scholar
Fliegner, J., Langer, N. 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. 326 Google Scholar
Friend, D., Abbott, D. 1986, ApJ 311, 701 Google Scholar
Grebel, E.K. 1997, A&A 317, 448 Google Scholar
Grebel, E.K., Roberts, W.J., Will, J.M., de Boer, K.S. 1994, SSR 66, 65 Google Scholar
Grebel, E.K., Roberts, W.J., Brandner, W. 1996, A&A 311, 470 Google Scholar
Herrero, A., Villmariz, M.R., Martin, E.L. 1998, in: Howarth, I.D. (ed.), Boulder-Münich II: Properties of Hot Luminous Stars, ASP-CS 131, 159 Google Scholar
Humphreys, R.M., Kudritzki, R.P., Groth, H.W. 1991, A&A 245, 593 Google Scholar
Langer, N., Fricke, K.J., Sugimoto, D. 1983, A&A 126, 207 Google Scholar
Langer, N., Maeder, A. 1995, A&A 295, 685 Google Scholar
Legrand, F., Kunth, D., Roy, J.R., Mas-Hesse, J.M., Walsh, J.R. 1997, A&A 326, L17 Google Scholar
Maeder, A. 1982, A&A 105, 149 Google Scholar
Maeder, A. 1997, A&A 321, 134 (paper II) Google Scholar
Maeder, A. 1999, A&A in press Google Scholar
Maeder, A., Conti, P.S. 1994, ARAA 32, 227 Google Scholar
Maeder, A., Zahn, J.P. 1998, A&A 334, 1000 (paper III) Google Scholar
Mazzali, P.A., Lennon, D.J., Pasian, F., Marconi, G., Baade, D., Castellani, V. 1996, A&A 316, 173 Google Scholar
Mermilliod, J.-C. 1982, A&A 109, 48 Google Scholar
Mermilliod, J.-C., Maeder, A. 1986, A&A 158, 45 Google Scholar
Meynet, G., Maeder, A. 1997, A&A 321, 465 Google Scholar
Meynet, G., Maeder, A. 1999, A&A in preparation Google Scholar
Meynet, G., Maeder, A., Schaller, G., Schaerer, D., Charbonnel, C. 1994, A&AS 103, 97 Google Scholar
Meynet, G., Mermilliod, J.-C., Maeder, A. 1993, A&A 98, 477 Google Scholar
Schaller, G., Schaerer, D., Meynet, G., Maeder, A. 1992, A&AS 96, 269 Google Scholar
Schaerer, D., Maeder, A. 1992, A&A 263, 129 Google Scholar
Smith, L.F., Maeder, A. 1991, A&A 241, 77 Google Scholar
Smith, L.F., Maeder, A. 1998, A&A 334, 845 Google Scholar
Venn, K.A., McCarthy, J.K., Lennon, D.J., Kudritzki, R.P. 1998, PASP 131, 177 Google Scholar
Zahn, J.P. 1992, A&A 265, 115 Google Scholar