Reconciling solar and stellar magnetic cycles with nonlinear dynamo simulations

TL;DR

This paper uses nonlinear dynamo simulations to explain how magnetic cycle periods in solar-type stars depend on stellar rotation and luminosity, aligning with observed stellar magnetic activity cycles.

Contribution

It demonstrates that the magnetic cycle period is inversely proportional to the Rossby number through nonlinear dynamo processes, matching observations of solar and stellar cycles.

Findings

Magnetic cycle period inversely proportional to Rossby number

Simulation results align with observed solar and stellar cycles

Nonlinear dynamo processes explain magnetic cycle dependencies

Abstract

The magnetic fields of solar-type stars are observed to cycle over decadal periods -11 years in the case of the Sun. The fields originate in the turbulent convective layers of stars and have a complex dependency upon stellar rotation rate. We have performed a set of turbulent global simulations that exhibit magnetic cycles varying systematically with stellar rotation and luminosity. We find that the magnetic cycle period is inversely proportional to the Rossby number, which quantifies the influence of rotation on turbulent convection. The trend relies on a fundamentally non-linear dynamo process and is compatible with the Sun's cycle and those of other solar-type stars.