On the cause of solar-like equatorward migration in global convective dynamo simulations

Abstract

We present results from four convectively-driven stellar dynamo simulations in spherical wedge geometry. All of these simulations produce cyclic and migrating mean magnetic fields. Through detailed comparisons we show that the migration direction can be explained by an $\alpha \Omega$ dynamo wave following the Parker--Yoshimura rule. We conclude that the equatorward migration in this and previous work is due to a positive (negative) $\alpha$ effect in the northern (southern) hemisphere and a negative radial gradient of $\Omega$ outside the inner tangent cylinder of these models. This idea is supported by a strong correlation between negative radial shear and toroidal field strength in the region of equatorward propagation.

6 pages, 5 figures, published in ApJ Letters

References in corpus (4)

• The case for a distributed solar dynamo shaped by near-surface shear
• Magnetic Cycles in a Convective Dynamo Simulation of a Young Solar-type Star
• Rapidly Rotating Suns and Active Nests of Convection
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• Analytic solution of an oscillatory migratory alpha^2 stellar dynamo
• Long-term variations of turbulent transport coefficients in a solar-like convective dynamo simulation
• Migrating Dynamo Waves and Consequences for Stellar Current Sheets
• The rotational influence on solar convection