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Massive Star Formation and Evolution in Local Group Galaxies: Successes and Difficulties

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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Local Group galaxies allow us to test some properties of massive star evolution which are inaccessible in our Galaxy, in particular the effects of different metallicities. Thus, after showing that we still do not know the exact process by which massive stars are formed, we examine the differences in the distributions of O-stars, blue and red supergiants and WR stars in the Local Group. The number ratios WR/O and WN/WC are well accounted for by stellar models in which the mass-loss rates depend on the metallicity, Z, as predicted by stellar wind theories. The number ratio of red supergiants to WR stars is growing for decreasing Z. Although this behaviour is qualitatively well explained, the models need some extra mixing to fit the observational data. The same is true for the explanation of the He- and N-excesses in O, B and A supergiants. Rotation and related mixing processes certainly play a major role in massive star evolution. The relative number of Be-stars is higher at lower Z, which suggests that rotation is faster, also with more mixing, in small, irregular low-metallicity galaxies.

Type
Part 3: Star Formation Processes and Chemical Evolution
Information
Symposium - International Astronomical Union , Volume 192: The Stellar Content of Local Group Galaxies , 1999 , pp. 291 - 303
Copyright
Copyright © Astronomical Society of the Pacific 1999 

References

Arnault, P., Kunth, D., Schild, H. 1989, A&A, 224, 73 Google Scholar
Barbuy, B., de Medeiros, J.R., Maeder, A. 1996, A&A, 305, 911 Google Scholar
Bernasconi, P.A., Maeder, A. 1996, A&A, 307, 829 Google Scholar
Bonnell, LA., Bate, M.R., Zinnecker, H. 1998, MNRAS, 298, 93 Google Scholar
Chiosi, C., Maeder, A. 1986, ARA&A, 24, 329 Google Scholar
Churchwell, E. 1998, in: Unsolved Problems of Stellar Evolution , (ed.) Livio, M., Cambridge Univ. Press, in press Google Scholar
Fitzpatrick, E.L., Bohannan, B. 1993, ApJ, 404, 734 Google Scholar
Fitzpatrick, E.L., Garmany, C.D. 1990, ApJ, 363, 119 Google Scholar
Fliegner, J., Langer, N., Venn, K.A. 1996, A&A, 308, L13 Google Scholar
Gies, D.R., Lambert, D.L. 1992, ApJ, 387, 673 Google Scholar
Grebel, E.K. 1997, A&A, 317, 448 Google Scholar
Grebel, E., Roberts, W.J., Will, J.M., de Boer, K.S. 1994, Space Sci. Rev., 66, 65 Google Scholar
Grebel, E.K., Roberts, W.J., Brandner, W. 1996, A&A, 311, 470 Google Scholar
Hamann, F., Ferland, G. 1993, ApJ, 418, 11 Google Scholar
Herrero, A., Villamariz, M.R., Martin, E.L. 1998, in: Boulder-Munich II: Properties of Hot, Luminous Stars , ASP Conf. Ser., 131, 159 Google Scholar
Humphreys, R. 1983, ApJ, 265, 170 Google Scholar
Iben, I. 1965, ApJ, 141, 993 Google Scholar
Langer, N., Maeder, A., 1995, A&A, 295, 685 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, ARA&A, 32, 227 Google Scholar
Maeder, A., Grebel, E., Azzopardi, M. 1999, A&A, in prep. Google Scholar
Maeder, A., Lequeux, J., Azzopardi, M. 1980, A&A, 90, L17 Google Scholar
Maeder, A., Meynet, G. 1994, A&A, 287, 803 Google Scholar
Maeder, A., Zahn, J.P. 1998, A&A, 334, 1000 (paper III) Google Scholar
Massey, P., Johnson, O. 1998, ApJ, 505, 793 Google Scholar
Meylan, G., Maeder, A. 1982, A&A, 108, 148 Google Scholar
Meylan, G., Maeder, A. 1983, A&A, 124, 84 Google Scholar
Meynet, G. 1992, in: The Feedback of Chemical Evolution on the Stellar Content of Galaxies , (eds.) Alloin, D. & Stasinska, G., Obs. de Paris, p. 40 Google Scholar
Meynet, G. 1995, A&A, 298, 767 Google Scholar
Meynet, G. 1998, in: Boulder-Munich II: Properties of Hot, Luminous Stars , ASP Conf. Ser., 131, 96 Google Scholar
Meynet, G., Maeder, A. 1997, A&A, 321, 465 (paper I) Google Scholar
Meynet, G., Mermilliod, J.C., Maeder, A. 1993, A&AS, 98, 477 Google Scholar
Norberg, P., Maeder, A., Meynet, G. 1999, A&A, in prep. Google Scholar
Palla, F., Stahler, S.W. 1993, ApJ, 418, 414 Google Scholar
Schaerer, D. 1996, ApJ, 467, L17 Google Scholar
Schaller, G., Schaerer, D., Meynet, G., Maeder, A. 1992, A&AS, 96, 269 Google Scholar
Smith, K.C., Howarth, I.D. 1994, A&A, 290, 868 Google Scholar
Stahler, S.W. 1998, in: Unsolved Problems of Stellar Evolution , (ed.) Livio, M., Cambridge Univ. Press, in press Google Scholar
Vacca, W., Conti, P.S. 1992, ApJ, 401, 543 Google Scholar
van der Hucht, K., Hidayat, B., Admiranto, A.G., Supelli, K.R., Doom, C. 1988, A&A, 199, 217 Google Scholar
Venn, K.A. 1995, ApJ, 449, 839 Google Scholar
Venn, K.A., Lambert, D.L., Lemke, M. 1996, A&A, 307, 849 Google Scholar
Venn, K.A., McCarthy, J.K., Lennon, D.J., Kudritzki, R.P. 1998, ASP Conf. Ser., 131, 177 Google Scholar
Walborn, N. 1988, in: Atmospheric Diagnostics of Stellar Evolution , IAU Coll. 108, (ed.) Nomoto, K., Springer-Verlag, Berlin, p. 70 Google Scholar
Watson, A.M., Hanson, M.M. 1997, ApJ, 490, L165 Google Scholar
Wolfire, M.G., Cassinelli, J.P. 1987, ApJ, 315, 315 Google Scholar
Zahn, J.P. 1992, A&A, 265, 115 Google Scholar