AAS 203rd Meeting, January 2004
Session 85 Stellar Structure, Evolution and Abundances
Poster, Wednesday, January 7, 2004, 9:20am-6:30pm, Grand Hall

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[85.02] Simulations of core convection in rotating A-type stars: Magnetic dynamo action

M.K. Browning (JILA, U. Colorado), A.S. Brun (CEA Saclay, and JILA), J. Toomre (JILA, U. Colorado)

We present the results of 3--D simulations of core convection dynamos within A-type stars of 2 solar masses, at a range of rotation rates. The inner 30% by radius of such stars are considered in our calculations, with the spherical domain thereby encompassing the convective core and some of the surrounding radiative envelope. We utilize our anelastic spherical harmonic (ASH) code to examine highly nonlinear flows that can admit magnetic dynamo action. Small initial seed magnetic fields are found to be amplified greatly by the convective and zonal flows. The resulting global fields possess structure on many scales, are strong enough to influence the convective flows themselves, and persist for as long as we have continued our calculations. The central columns of strikingly slow rotation found in some of our progenitor hydrodynamic simulations continue to be realized here to a lesser degree, with such differential rotation arising from the redistribution of angular momentum by the nonlinear convection and magnetic fields. We assess the properties of the magnetic fields, the extent of convective penetration, and the excitation of gravity waves within the radiative envelope.

The author(s) of this abstract have provided an email address for comments about the abstract: matthew.browning@colorado.edu

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© 2003. The American Astronomical Soceity.