Magnetic Cycles in Global Large-eddy Simulations of Solar Convection

We report on a global magnetohydrodynamical simulation of the solar convection zone, which succeeds in generating a large-scale axisymmetric magnetic component, antisymmetric about the equatorial plane and undergoing regular polarity reversals on decadal timescales. We focus on a specific simulation...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2010-06, Vol.715 (2), p.L133-L137
Main Authors: Ghizaru, Mihai, Charbonneau, Paul, Smolarkiewicz, Piotr K
Format: Article
Language:English
Subjects:
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
AXIAL SYMMETRY
COMPUTERIZED SIMULATION
CONVECTION
DIPOLE MOMENTS
ENERGY TRANSFER
FLUID MECHANICS
HEAT TRANSFER
HYDRODYNAMICS
LARGE-EDDY SIMULATION
MAGNETOHYDRODYNAMICS
MAIN SEQUENCE STARS
MASS TRANSFER
MEAN-FIELD THEORY
MECHANICS
SIMULATION
SOLAR ACTIVITY
STARS
STARSPOTS
STELLAR ACTIVITY
SUN
SUNSPOTS
SYMMETRY
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Summary:We report on a global magnetohydrodynamical simulation of the solar convection zone, which succeeds in generating a large-scale axisymmetric magnetic component, antisymmetric about the equatorial plane and undergoing regular polarity reversals on decadal timescales. We focus on a specific simulation run covering 255 years, during which 8 polarity reversals are observed, with a mean period of 30 years. Time-latitude slices of the zonally averaged toroidal magnetic component at the base of the convecting envelope show a well-organized toroidal flux system building up in each solar hemisphere, peaking at mid-latitudes and migrating toward the equator in the course of each cycle, in remarkable agreement with inferences based on the sunspot butterfly diagram. The simulation also produces a large-scale dipole moment, varying in phase with the internal toroidal component, suggesting that the simulation may be operating as what is known in mean-field theory as an {alpha}{Omega} dynamo.
ISSN:2041-8205
2041-8213
DOI:10.1088/2041-8205/715/2/L133