Spoke-like differential rotation in a convective dynamo with a coronal envelope

Abstract

We report on the results of four convective dynamo simulations with an outer coronal layer. The magnetic field is self-consistently generated by the convective motions beneath the surface. Above the convection zone, we include a polytropic layer that extends to 1.6 solar radii. The temperature increases in this region to $\approx 8$ times the value at the surface, corresponding to $\approx 1.2$ times the value at the bottom of the spherical shell. We associate this region with the solar corona. We find solar-like differential rotation with radial contours of constant rotation rate, together with a near-surface shear layer. This non-cylindrical rotation profile is caused by a non-zero latitudinal entropy gradient that offsets the Taylor--Proudman balance through the baroclinic term. The meridional circulation is multi-cellular with a solar-like poleward flow near the surface at low latitudes. In most of the cases, the mean magnetic field is oscillatory with equatorward migration in two cases. In other cases, the equatorward migration is overlaid by stationary or even poleward migrating mean fields.

16 pages, 14 figure, published in ApJ

References in corpus (19)

• Global-Scale Turbulent Convection and Magnetic Dynamo Action in the Solar Envelope
• The case for a distributed solar dynamo shaped by near-surface shear
• Detection of Equatorward Meridional Flow and Evidence of Double-Cell Meridional Circulation inside the Sun
• Mean-field concept and direct numerical simulations of rotating magnetoconvection and the geodynamo
• Solar differential rotation and meridional flow: The role of a subadiabatic tachocline for the Taylor-Proudman balance
• Magnetic Cycles in a Convective Dynamo Simulation of a Young Solar-type Star
• Magnetic Wreaths and Cycles in Convective Dynamos
• Cyclic magnetic activity due to turbulent convection in spherical wedge geometry
• Rapidly Rotating Suns and Active Nests of Convection
• Effects of enhanced stratification on equatorward dynamo wave propagation
• Dipolar versus multipolar dynamos: the influence of the background density stratification
• Importance of Meridional Circulation in Flux Transport Dynamo: The Possibility of a Maunder-like Grand Minimum
• Reynolds stress and heat flux in spherical shell convection
• Simulations of turbulent convection in rotating young solar-like stars: Differential rotation and meridional circulation
• Catastrophic alpha quenching alleviated by helicity flux and shear
• Bipolar magnetic structures driven by stratified turbulence with a coronal envelope
• Solar dynamo models with alpha-effect and turbulent pumping from local 3D convection calculations
• Surface appearance of dynamo-generated large-scale fields
• Simulations of the anisotropic kinetic and magnetic alpha effects

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