Hostname: page-component-cd9895bd7-mkpzs Total loading time: 0 Render date: 2024-12-29T02:05:46.534Z Has data issue: false hasContentIssue false
  • English
  • Français

The basic role of magnetic fields in stellar evolution

Published online by Cambridge University Press:  01 November 2008

André Maeder ,
Georges Meynet ,
Cyril Georgy  and
Sylvia Ekström
André Maeder
Affiliation:
Geneva Observatory, CH-1290 Sauverny, Switzerland
Georges Meynet
Affiliation:
Geneva Observatory, CH-1290 Sauverny, Switzerland
Cyril Georgy
Affiliation:
Geneva Observatory, CH-1290 Sauverny, Switzerland
Sylvia Ekström
Affiliation:
Geneva Observatory, CH-1290 Sauverny, Switzerland
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Magnetic field is playing an important role at all stages of star evolution from star formation to the endpoints. The main effects are briefly reviewed. We also show that O–type stars have large convective envelopes, where convective dynamo could work. There, fields in magnetostatic balance have intensities of the order of 100 G.

A few OB stars with strong polar fields (Henrichs et al. 2003a) show large N–enhancements indicating a strong internal mixing. We suggest that the meridional circulation enhanced by an internal rotation law close to uniform in these magnetic stars is responsible for the observed mixing. Thus, it is not the magnetic field itself which makes the mixing, but the strong thermal instability associated to solid body rotation.

A critical question for evolution is whether a dynamo is at work in radiative zones of rotating stars. The Tayler-Spruit (TS) dynamo is the best candidate. We derive some basic relations for dynamos in radiative layers. Evolutionary models with TS dynamo show important effects: internal rotation coupling and enhanced mixing, all model outputs being affected.

Keywords

Stars – magnetic fields – stars: evolution
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 4 , Symposium S259: Cosmic Magnetic Fields: From Planets, to Stars and Galaxies , November 2008 , pp. 311 - 322
Copyright
Copyright © International Astronomical Union 2009

References

Braithwaite, J. 2006, A&A 449, 451Google Scholar
Churchwell, E. 1998, in the Origin of Stars and Planetary Systems, Ed. Lada, C. and Kylafis, N., NATO Science Ser. 540, Kluwer, p. 515Google Scholar
Eggenberger, P. 2005, A&A 440, L9Google Scholar
Hartmann, L. 1998, Accretion Processes in Star Formation, Cambridge Univ. Press.Google Scholar
Henning, Th.Schreyer, K, & Launhardt, R. et al. 2000, A&A 353, 211Google Scholar
Henrichs, H. F., Neiner, C., & Geers, V. C. 2003a, Intl. Conf. on magnetic fields in O, B and A stars, Eds. van der Hucht, K. A. et al. , IAU Symp. 212, 202Google Scholar
Henrichs, H. F., Neiner, C., & Geers, V. C. 2003b, A Massive Star Odysses, from Main Sequence to Supernova, ASP Conf. Ser. 305, 301Google Scholar
Hubrig, S., Schöller, M., & Schnerr, R. S. et al. 2008, A&A 490, 793Google Scholar
Kawaler, S. D. 1988, ApJ 333, 236Google Scholar
Krishnamurti, A., Pinsonneault, M. H., & Barnes, S. et al. 1997, ApJ 480, 303CrossRefGoogle Scholar
Maeder, A., Georgy, C., & Meynet, G. 2008, A&A 479, L37Google Scholar
Maeder, A. & Meynet, G. 2004, A&A 422, 225Google Scholar
Maeder, A. & Meynet, G. 2005, A&A 440, 1041Google Scholar
Mathys, G. 2004, Stellar Rotation, IAU Symp 215, Eds. Maeder, A., Eeneens, P., p. 270CrossRefGoogle Scholar
Meynet, G. & Maeder, A. 2000, A&A 361, 101Google Scholar
Mouschovias, T. Ch. & Spitzer, L. 1976, ApJ 210, 326Google Scholar
Safier, P. N. 1999 ApJ 510, L127CrossRefGoogle Scholar
Spruit, H. C. 2002 A&A 381, 923Google Scholar
Zahn, J.-P., Brun, A. S., & Mathis, S. 2007, A&A 474, 145Google Scholar