An Isaac Newton Institute Workshop

Pattern Formation in Fluid Mechanics

Spatial Modulation and Dynamo Action in Global Simulations of Stellar Convection

Author: Benjamin Brown (JILA, University of Colorado)

Abstract

Many solar-like stars rotate more rapidly than the sun. Through their magnetized winds, these stars gradually lose angular momentum and spin down. Indeed the sun itself once rotated more rapidly than it currently does. Here we explore the effects of more rapid rotation upon turbulent stellar convection, and in particular the nature of magnetic dynamo action at higher rotation rates. Our 3-D simulations of compressible turbulent convection are carried out with the Anelastic Spherical Harmonic (ASH) code on massively parallel supercomputers. For simplicity, we adopt the radial stratification of the present-day sun and examine global scale convection in a zone extending from 0.72 to 0.97 solar radii. We explore the structure of convection and interactions between convection and magnetism. At moderate rotation rates striking patterns of spatially localized convection appear. These persistent patches of convection are robust features and appear throughout our parameter space. We assess the formation of these coherent structures amidst turbulent convection and examine the resulting dynamo action.