LAMBDA-QUENCHING AS THE NONLINEARITY IN STELLAR-TURBULENCE DYNAMOS

A novel scenario for the nonlinear stellar dynamo is presented. Differ ential rotation in solar-type stars is assumed as due to the influence of the global rotation upon anisotropic turbulence (''the Lambda-effe ct''). The effect, however, is quenched by the dynamo-induced large-sc ale magnetic fields. The resulting reduction of the differential rotat ion feeds back on the dynamo itself. Both the derivation of the h-quen ching expressions as well as a (simplified) dynamo model are presented . The dynamo equation is completed with the equation for the radial di fferential rotation. The phase relation between both the components of the magnetic field and the slope in the rotation law is essential for the temporal behaviour of the dynamo magnetism. Both the observationa l phenomena of solar torsional oscillations as well as the Maunder min imum are covered by the theory.