Simulations of core convection and resulting dynamo action in rotating Atype stars
Abstract
We present the results of 3D nonlinear simulations of magnetic dynamo action by core convection within Atype stars of 2 M_{☉} with a range of rotation rates. We consider the inner 30% by radius of such stars, with the spherical domain thereby encompassing the convective core and a portion of the surrounding radiative envelope. The compressible NavierStokes equations, subject to the anelastic approximation, are solved to examine highly nonlinear flows that span multiple scale heights, exhibit intricate time dependence, and admit magnetic dynamo action. Small initial seed magnetic fields are found to be amplified greatly by the convective and zonal flows. The central columns of strikingly slow rotation found in some of our progenitor hydrodynamic simulations continue to be realized in some simulations 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 thus generated, the extent of the convective penetration, the magnitude of the differential rotation, and the excitation of gravity waves within the radiative envelope.
 Publication:
 The AStar Puzzle
 Pub Date:
 December 2004
 DOI:
 10.1017/S1743921304004491
 arXiv:
 arXiv:astroph/0409703
 Bibcode:
 2004IAUS..224..149B
 Keywords:

 Convection;
 magnetic fields;
 turbulence;
 stars: interiors;
 Astrophysics
 EPrint:
 Talk at IAU Symposium 224: The AStar Puzzle. 6 pages, 3 figures, 2 in color, compressed with appreciable loss of quality