Magnetic feedback on stellar convective zones

This paper summarises the latest results of our investigation of the impact of magnetic fields on the overall dynamics of the convective envelopes of cool active stars. Estimations of surface differential rotation in these stars, derived from either magnetic and brightness Doppler imaged surface features, as well as of its temporal variations, turn out to be extremely useful and provide very rich information for our study. From a preliminary modelling, our observations suggest that the rotation velocity field within the convective zone of the stars we investigated is, unsurprisingly, closer to that expected for rapid rotators (with constant angular velocity on cylinders aligned with the rotation axis) than to that of the Sun. The power required to drive the observed changes in the differential rotation within the convective zone are estimated to be of the order of 1 to 10% of the total stellar luminosity. We speculate that these changes result from the dynamo processes operating in these stars (and from the underlying magnetic cycle) that periodically converts magnetic energy into kinetic energy and vice versa.