Modeling Sun-like Stars
Benjamin P. Brown [bpbrown@astro.wisc.edu], Dept. of Astronomy and Center for
Magnetic Self-Organization in Laboratory and Astrophysical Plasmas (CMSO), University
of Wisconsin, Madison
Magnetism is a ubiquitous feature of solar-type stars. The magnetic fields observed at
the stellar photospheres arise from dynamo action in the convective envelopes, where plasma
motions couple with rotation to build global-scale magnetic fields. Here we discuss recent
global-scale, 3-D MHD simulations of convection and dynamo action in stellar interiors with
the anelastic spherical harmonic (ASH) code. For the first time, a variety of global-scale
simulations are building global magnetic fields without relying on stable tachoclines of shear
for storage or large-scale organization. Instead, these global-scale magnetic fields are built in
the bulk of the convection zone, forming large wreath-like structures that coexist with the
turbulent convection. These dynamos can undergo regular and cyclic reversals of magnetic
polarity and some are now even building magnetic structures that become buoyantly unstable
and rise toward the stellar photospheres. We’ll explore these cyclic wreath-building
dynamos in G- and K-type stars rotating at the solar rate and faster, as the Sun did when
younger.