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Exploring the deep convection and magnetism of A-type stars

Published online by Cambridge University Press:  26 August 2011

Nicholas A. Featherstone
Affiliation:
JILA and Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309-0440, USA email: feathern@lcd.colorado.edu
Matthew K. Browning
Affiliation:
Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, ON M5S3H8, Canada
Allan Sacha Brun
Affiliation:
DSM/IRFU/SAp, CEA-Saclay and UMR AIM, CEA-CNRS-Universite Paris 7, 91191 Gif-sur-Yvette, France
Juri Toomre
Affiliation:
JILA and Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309-0440, USA email: feathern@lcd.colorado.edu
Corresponding
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Abstract

A-type stars have both a near-surface layer of fast convection that can excite acoustic modes and a deep zone of core convection whose properties may be probed with asteroseismology. Many A-type stars also exhibit large magnetic spots that are often attributed to surviving primordial fields of global scale in the intervening radiative zone. We have explored the potential for core convection in rotating A-type stars to build strong magnetic fields through dynamo action. These 3-D simulations using the ASH code provide guidance on the nature of differential rotation and magnetic fields that may be present in the deep interiors of these stars, thus informing the asteroseismic deductions now becoming feasible. Our models encompass the inner 30% by radius of a two solar mass A-type star, rotating at four times the solar rate and capturing the convective core and a portion of the overlying radiative envelope. Convection in these stars drives a strong retrograde differential rotation and yields a core that is prolate in shape. When dynamo action is admitted, the convection generates strong magnetic fields largely in equipartition with the dynamics. Remarkably, introducing a modest but large-scale external field threading the radiative envelope (which may be of primordial origin) can substantially alter the turbulent dynamics of the convective interior. The resulting convection involves a complex assembly of helical rolls that link distant portions of the core and stretch and advect magnetic field, ultimately yielding magnetic fields of super-equipartition strength.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2011

References

Aurière, M. et al. , 2007, A&A 475 1053Google Scholar
Braithwaite, J. & Spruit, H. C., 2004 Nature 431 819CrossRefGoogle Scholar
Browning, M. K., Brun, A. S., & Toomre, J., 2004, ApJ 601 512CrossRefGoogle Scholar
Brun, A. S., Browning, M. K., & Toomre, J., 2005 ApJ 629 461CrossRefGoogle Scholar
Brun, A. S., Miesch, M. S., & Toomre, J., 2004 ApJ 614 1073CrossRefGoogle Scholar
Busse, F. H., 2002 Phys. Fluids f 14 1301CrossRefGoogle Scholar
Deutsch, A. J., 1956 PASP 68 92CrossRefGoogle Scholar
Featherstone, N. A., Browning, M. K., Brun, A. S., & Toomre, J. 2009 ApJ 705 1000CrossRefGoogle Scholar
Mestel, L., 1999 Stellar Magnetism (Oxford: Clarendon Press)Google Scholar
Prendergast, K. H., 1956 ApJ 123 498CrossRefGoogle Scholar
Preston, G. W., 1971 PASP 83 571CrossRefGoogle Scholar

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