Dynamo cycles in global convection simulations of solar-like stars

Abstract

Several solar-like stars exhibit cyclic magnetic activity similar to the Sun as found in photospheric and chromospheric emission. We want to understand the physical mechanism involved in rotational dependence of these activity cycle periods. We use three-dimensional magnetohydrodynamical simulations of global convective dynamos models of solar-like stars to investigate the rotational dependency of dynamos. We further apply the test-field method to determine the $\alpha$ effect in these simulations. We find dynamo with clear oscillating mean magnetic fields for moderately and rapidly rotating runs. For slower rotation, the field is constant or exhibit irregular cycles. In the moderately and rapidly rotating regime the cycle periods increase weakly with rotation. This behavior can be well explained with a Parker-Yoshimura dynamo wave traveling equatorward. Even though the $\alpha$ effect becomes stronger for increasing rotation, the shear decreases steeper, causing this weak dependence on rotation. Similar as other numerical studies, we find no indication of activity branches as suggested by Brandenburg et al. (1998). However, our simulation seems to agree more with the transitional branch suggested by Distefano et al. (2017) and Olspert et al. (2017). If the Sun exhibit a dynamo wave similar as we find in our simulations, it would operate deep inside the convection zone.

11 pages, 10 figures, accepted for publication in A&A

References in corpus (16)

• The case for a distributed solar dynamo shaped by near-surface shear
• Chromospheric activity catalogue of 4454 cool stars. Questioning the active branch of stellar activity cycles
• Mean-field concept and direct numerical simulations of rotating magnetoconvection and the geodynamo
• A simulation of convective dynamo in the solar convective envelope: maintenance of the solar-like differential rotation and emerging flux
• Global Seismology of the Sun
• Rapidly Rotating Suns and Active Nests of Convection
• Alpha effect and turbulent diffusion from convection
• Magnetically controlled stellar differential rotation near the transition from solar to anti-solar profiles
• Reconciling solar and stellar magnetic cycles with nonlinear dynamo simulations
• Evidence for photometric activity cycles in 3203 Kepler stars
• Estimating activity cycles with probabilistic methods II. The Mount Wilson Ca H&K data
• Transition from axi- to nonaxisymmetric dynamo modes in spherical convection models of solar-like stars
• On the cause of solar-like equatorward migration in global convective dynamo simulations
• The radial gradient of the near-surface shear layer of the Sun
• Activity cycles in members of young loose stellar associations
• Long-term variations of turbulent transport coefficients in a solar-like convective dynamo simulation

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