Magnetic cycles

Magnetic cycles in a magnetohydrodynamical numerical simulation of solar convection. This sequence spans a little over 400 years, and begins (at left) from a low-amplitude random seed magnetic field and velocity perturbations. The plot shows combined time-latitude and radius-latitude representations of the zonally-averaged toroidal magnetic component, extracted respectively below the core-envelope interface and at 50 degrees latitude North. The color scale codes the longitudinal component of the magnetic field, red-yellow for increasingly intense positive magnetic polarity (pointing in the direction of solar rotation), and blue-green for increasingly negative toroidal field, peaking here at +/- 0.3 Tesla. Dynamo action takes place throughout the convective layers (above the white dashed line on the time-radius cut), with strong toroidal field accumulating immediately below the interface, within the convectively stable fluid layers. Near the end of this simulation run, the Southern hemisphere goes through an abnormally long cycle, changing the equatorial parity from antisymmetric to symmetric.

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Ghizaru, M., Charbonneau, P., et Smolarkiewicz, P.K., Magnetic cycles in a large eddy simulation of solar convection, The Astrophysical Journal Letters, 715, L133-L137; on ADS
Racine, E., Charbonneau, P., Ghizaru, M., Bouchat, A., et Smolarkiewicz, P.K., On the mode of dynamo action in a global large-eddy simulation of solar convection, The Astrophysical Journal, 735, id46; on ADS