 Stellar rotation-activity feedback

Rotation influences convection, its helicity and differential rotation, which feed dynamo action. The generated magnetic field produces surface activity and strengthens the angular-momentum lever arm of a stellar wind. Wind braking lowers the rotation rate and ordinarily reduces unsaturated activity. Lorentz force feedback also changes the differential rotation and convective motions, saturating the dynamo on shorter time scales. Secular evolution, cyclic polarity reversal and irregular modulation are distinct time scales of this coupled system.