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Large-scale magnetic fields of low-mass dwarfs: the many faces of dynamo

Published online by Cambridge University Press:  12 August 2011

J.-F. Donati
J.-F. Donati*
Affiliation:
CNRS/Université de Toulouse, Observatoire Midi-Pyrérées, Toulouse, France email: [email protected]
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Abstract

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Magnetic field are ubiquitous to low-mass stars and can potentially impact their evolution and their internal structure; yet the physical processes (called dynamo) that succeed at generating them in the stellar convective zones of cool dwarfs are still enigmatic. Although theoretical modelling and numerical simulations of stellar dynamo action showed breathtaking progress in the last decade, they are not yet in the state of accurately predicting the various magnetic topologies that different low-mass stars can generate.

Thanks to the advent of new-generation instruments, spectropolarimetric observations can now reveal the large-scale magnetic topologies of cool dwarfs, from the brown dwarf threshold (spectral type M8) up to the limit beyond which outer convective zones get vanishingly small (spectral type F5). In particular, they can reconstruct through tomographic methods the poloidal and toroidal components of the large-scale field, hence offering a fresh option for guiding dynamo theories to a more mature state.

We review here the latest observational advances, showing in particular that magnetic topologies of low-mass dwarfs can drastically vary with mass and rotation rate, and discuss their implications for our understanding of dynamo processes.

Keywords

stars: magnetic fieldsstars: imagingstars: rotationstars: late-typetechniques: polarimetry
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 6 , Symposium S271: Astrophysical Dynamics: From Stars to Galaxies , June 2010 , pp. 23 - 31
Copyright
Copyright © International Astronomical Union 2011

References

Baraffe, I., Chabrier, G., Allard, F., & Hauschildt, P. H., 1998, A&A 337, 403Google Scholar
Berdyugina, S. V., 2005, Living Reviews in Solar Physics 2, 8CrossRefGoogle Scholar
Berger, E., Rutledge, R. E., Reid, I. N., et al. , 2005, ApJ 627, 960CrossRefGoogle Scholar
Brandenburg, A., 2005, ApJ 625, 539CrossRefGoogle Scholar
Browning, M. K., 2008, ApJ 676, 1262CrossRefGoogle Scholar
Brun, A. S., Browning, M. K., & Toomre, J., 2005, ApJ 629, 461CrossRefGoogle Scholar
Cameron, A. C. & Robinson, R. D., 1989, MNRAS 236, 57CrossRefGoogle Scholar
Chabrier, G. & Küker, M., 2006, A&A 446, 1027Google Scholar
Charbonneau, P., 2005, Living Reviews in Solar Physics 2, 2CrossRefGoogle Scholar
Dikpati, M. & Charbonneau, P., 1999, ApJ 518, 508CrossRefGoogle Scholar
Dobler, W., Stix, M., & Brandenburg, A., 2006, ApJ 638, 336CrossRefGoogle Scholar
Donati, J.-F., 1999, MNRAS 302, 457CrossRefGoogle Scholar
Donati, J.-F., Brown, S. F., Semel, M. et al. , 1992, A&A 265, 682Google Scholar
Donati, J.-F. & Cameron, A. C., 1997, MNRAS 291, 1CrossRefGoogle Scholar
Donati, J.-F., Cameron, A. C., Semel, M. et al. , 2003a, MNRAS 345, 1145CrossRefGoogle Scholar
Donati, J.-F., Cameron, A. C., & Petit, P., 2003b, MNRAS 345, 1187CrossRefGoogle Scholar
Donati, J.-F., Forveille, T., Cameron, A. C. et al. , 2006, Science 311, 633CrossRefGoogle Scholar
Donati, J.-F. & Landstreet, J. D., 2009, ARA&A 47, 333Google Scholar
Donati, J.-F., Morin, J., Petit, P., et al. , 2008b, MNRAS 390, 545CrossRefGoogle Scholar
Donati, J.-F., Moutou, C., Fares, R., et al. , 2008a, MNRAS 385, 1179CrossRefGoogle Scholar
Donati, J.-F., Semel, M., Carter, B. D., Rees, D. E. & Collier Cameron, A. 1997, MNRAS, 291, 658CrossRefGoogle Scholar
Dunstone, N. J., Hussain, G. A. J., Cameron, A. C., et al. , 2008, MNRAS 387, 1525CrossRefGoogle Scholar
Durney, B. R., De Young, D. S., & Roxburgh, I. W., 1993, Sol. Phys. 145, 207CrossRefGoogle Scholar
Fares, R., Donati, J.-F., Moutou, C., et al. , 2009, MNRAS 398, 1383CrossRefGoogle Scholar
Goudard, L. & Dormy, E., 2008, Europhysics Letters 83, 59001CrossRefGoogle Scholar
Hallinan, G., Antonova, A., Doyle, J. G., et al. , 2008, ApJ 684, 644CrossRefGoogle Scholar
Hall, J. C., 2008, Living Reviews in Solar Physics 5, 2CrossRefGoogle Scholar
Hall, D. S., 1991, in LNP 380, 353 (Berlin Springer Verlag)Google Scholar
Johns-Krull, C. M. & Valenti, J. A., 1996, ApJ 459, L95CrossRefGoogle Scholar
Küker, M. & Rüdiger, G., 1997, A&A 328, 253Google Scholar
Lites, B. W., Kubo, M., Socas-Navarro, H., et al. , 2008, ApJ 672, 1237CrossRefGoogle Scholar
Mangeney, A. & Praderie, F., 1984, A&A 130, 143Google Scholar
Marsden, S. C., Donati, J.-F., Semel, M., Petit, P. & Carter, B. D., 2006, MNRAS 370, 468CrossRefGoogle Scholar
Mestel, L., 1999, Stellar magnetism (Oxford: Clarendon)Google Scholar
Morin, J., Donati, J.-F., Forveille, T., et al. , 2008a, MNRAS 384, 77CrossRefGoogle Scholar
Morin, J., Donati, J.-F., Petit, P., et al. , 2008b, MNRAS 390, 567CrossRefGoogle Scholar
Morin, J., Donati, J.-F., Petit, P., et al. , 2010, MNRAS (in press)Google Scholar
Noyes, R. W., Hartmann, L. W., Baliunas, S. L., Duncan, D. K., & Vaughan, A. H., 1984, ApJ 279, 763CrossRefGoogle Scholar
Petit, P., Donati, J.-F., Auriere, M., et al. , 2005, MNRAS 361, 837CrossRefGoogle Scholar
Petit, P., Dintrans, B., Solanki, S. K., et al. , 2008, MNRAS 388, 80CrossRefGoogle Scholar
Reiners, A., 2006, A&A 446, 267Google Scholar
Reiners, A. & Basri, G., 2008, ApJ 684, 1390CrossRefGoogle Scholar
Robinson, R. D., Worden, S. P., & Harvey, J. W., 1980, ApJ 236, L155CrossRefGoogle Scholar
Saar, S. H., 2001, in: ASP Conf Series 223, 292Google Scholar
Schatzman, E., 1962, AnAp 25, 18Google Scholar