Hostname: page-component-8448b6f56d-dnltx Total loading time: 0 Render date: 2024-04-19T08:42:12.626Z Has data issue: false hasContentIssue false
  • English
  • Français

MHD relaxation of fossil magnetic fields in stellar interiors

Published online by Cambridge University Press:  12 August 2011

Stéphane Mathis ,
Vincent Duez  and
Jonathan Braithwaite
Stéphane Mathis
Affiliation:
Laboratoire AIM, CEA/DSM-CNRS-Université Paris Diderot, IRFU/SAp Centre de Saclay, F-91191 Gif-sur-Yvette, France email: stephane.mathis@cea.fr Observatoire de Paris-LESIA 5, place Jules Janssen, F-92195 Meudon Cedex
Vincent Duez
Affiliation:
Argelander Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, D-53111 Bonn, Germany email: vduez@astro.uni-bonn.de; jonathan@astro.uni-bonn.de
Jonathan Braithwaite
Affiliation:
Argelander Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, D-53111 Bonn, Germany email: vduez@astro.uni-bonn.de; jonathan@astro.uni-bonn.de
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.

The understanding of fossil fields origin, topology, and stability is one of the corner stones of the stellar magnetism theory. On one hand, since they survive on secular time scales, they may modify the structure and the evolution of their host stars. On the other hand, they must have a complex stable structure since it has been demonstrated that the simplest purely poloidal or toroidal fields are unstable on dynamical time scales. In this context, the only stable stellar configurations found today are those resulting from numerical simulations by Braithwaite and collaborators who studied the evolution of an initial stochastic magnetic field, which relaxes with a selective decay of magnetic helicity and energy, on mixed stable configurations (poloidal and toroidal) that seem to be in equilibrium and then diffuse. In this talk, we report the semi-analytical investigation of such an equilibrium field in the axisymmetric case. We use variational methods, which describe selective decay of magnetic helicity and energy during MHD relaxation, and we identify a supplementary invariant due to the stable stratification of stellar radiation zones. This leads to states that generalize force-free Taylor's relaxation states studied in plasma laboratory experiments that become non force-free in the stellar case. Moreover, astrophysical applications are presented and the stability of obtained configurations is studied.

Keywords

magnetohydrodynamics (MHD)plasmasstars: magnetic field
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 6 , Symposium S271: Astrophysical Dynamics: From Stars to Galaxies , June 2010 , pp. 270 - 278
Copyright
Copyright © International Astronomical Union 2011

References

Alecian, E., et al. 2008, A&A, 481, L99Google Scholar
Aurière, M., et al. 2007, A&A, 475, 1053Google Scholar
Biskamp, D. 1997, Nonlinear Magnetohydrodynamics (Cambridge, UK: Cambridge University Press)Google Scholar
Bonanno, A. & Urpin, V. 2008a, A&A, 488, 1Google Scholar
Bonanno, A. & Urpin, V. 2008b, A&A, 477, 35Google Scholar
Braithwaite, J. 2006, A&A, 449, 451Google Scholar
Braithwaite, J. 2008, MNRAS, 386, 1947CrossRefGoogle Scholar
Braithwaite, J. 2009, MNRAS, 397, 763CrossRefGoogle Scholar
Braithwaite, J. & Spruit, H. C. 2004, Nature, 431, 819CrossRefGoogle Scholar
Braithwaite, J. & Nordlund, Å. 2006, A&A, 450, 1077Google Scholar
Brun, A. S. 2007, AN, 328, 1137Google Scholar
Brun, A. S. & Zahn, J.-P. 2006, A&A, 457, 665Google Scholar
Busse, F. H. 1981, Geophysical and Astrophysical Fluid Dynamics, 17, 215CrossRefGoogle Scholar
Commerçon, B., Hennebelle, P., Audit, E., Chabrier, G., & Teyssier, R. 2010, A&A, 510, L3Google Scholar
Decressin, T., Mathis, S., Palacios, A., Siess, L., Talon, S., Charbonnel, C., & Zahn, J.-P. 2009, A&A, 495, 271Google Scholar
Duez, V. & Mathis, S. 2010, A&A, 517, A58Google Scholar
Duez, V., Braithwaite, J., & Mathis, S. 2010, ApJ, acceptedGoogle Scholar
Duez, V., Mathis, S., & Turck-Chièze, S. 2010, MNRAS, 402, 271CrossRefGoogle Scholar
Eff-Darwich, A., Korzennik, S. G., Jiménez-Reyes, S. J., & García, R. A. 2008, ApJ, 679, 1636CrossRefGoogle Scholar
Elstner, D., Bonanno, A., & Rüdiger, G. 2008, A&A, 329, 717Google Scholar
Grad, H. & Rubin, H. 1958, Proceedings of the Second United Nations International Conference on the Peaceful Uses of Atomic Energy, Vol. 31, IAEA, Geneva, 190–197Google Scholar
Garaud, P. & Guervilly, C. 2009, ApJ, 695, 799CrossRefGoogle Scholar
Grunhut, J. H., et al. 2009, MNRAS, 400, L94CrossRefGoogle Scholar
Heinemann, M. & Olbert, S. 1978, Journal of Geophysical Research, 83, 2457CrossRefGoogle Scholar
Mathis, S. & Zahn, J.-P. 2005, A&A, 440, 653Google Scholar
Mestel, L., Moss, D., & Tayler, R. J. 1988, MNRAS, 231, 873CrossRefGoogle Scholar
Moffatt, H. K. 1985, J. Fluid Mechanics, 159, 359CrossRefGoogle Scholar
Montgomery, D. & Phillips, L. 1988, Phys. Rev. A, 38, 2953CrossRefGoogle Scholar
Montgomery, D. & Phillips, L. 1989, Physica D, 37, 215CrossRefGoogle Scholar
Nordlund, Å. & Galsgaard, K. 1995, A 3D MHD code for Parallel Computers, Tech. rep., http://www.astro.ku.dk/~aake/papers/95.ps.gzGoogle Scholar
Prendergast, K. H. 1956, ApJ, 123, 498CrossRefGoogle Scholar
Reisenegger, A. 2009, A&A, 499, 557Google Scholar
Shafranov, V. D. 1966, Reviews of Plasma Physics, 2, 103Google Scholar
Shaikh, D., Dasgupta, B., Hu, Q., & Zank, G. P. 2008, J. Plasma Physics, 75, 273Google Scholar
Spruit, H. C. 2002, A&A, 381, 923Google Scholar
Tayler, R. J. 1973, MNRAS, 161, 365CrossRefGoogle Scholar
Taylor, J. B. 1974, Phys. Rev. Lett., 33, 1139CrossRefGoogle Scholar
Woltjer, L. 1959, ApJ, 130, 405CrossRefGoogle Scholar
Woltjer, L. 1960, ApJ, 131, 227CrossRefGoogle Scholar
Wright, G. A. E. 1973, MNRAS, 162, 339CrossRefGoogle Scholar
Zahn, J.-P. 1992, A&A, 265, 115Google Scholar