Role of helicity fluctuations in kinematic dynamo models

P.D. MININNI Y D.O. GOMEZ

Santiago, Chile

Workshop; Magnetic fields across the Hertzsprung-Russell diagram; 2001

ESO

We present a model where nonlinear effects are responsible for the saturation of the magnetic field, while irregularities are introduced using a random forcing term in the helicity of the flow. We consider a simple 1D model in spherical coordinates and integrate the kinematic dynamo equation. The model is characterized by a solar-like differential rotation profile, as well as meridional circulation in the computational shell. Nonlinearities are introduced in the form of alpha-quenching, considering the back-reaction of the magnetic field into the velocity field. In spite of the simplicity of our model, we manage to reproduce several observed features, such as the 22-year magnetic cycle and butterfly diagrams qualitatively resembling those displayed by the Sun.