Large-scale non-axisymmetric magnetic fields on the sun and cool stars

The magnetic activity of the Sun is known to be asymmetric in both North-South (N-S) and East-West (E-W) directions. While the existence of the N-S asymmetry was largely accepted and confirmed by numerous studies of various features of solar activity, the E-W asymmetry was not so obvious oil longer time scales. The modulation of the activity with nearly the solar rotation period suggests however for the existence of long-lived complexes of activity at preferred longitudes. For instance, two preferred active longitudes in both Southern and Northern hemispheres were found to be persistent at the century time scale. The pattern and behaviour of the active longitudes on the Sun was found to be similar to that on cool, rapidly rotating stars with outer convective envelopes. This suggests that the magnetic dynamo processes are similar in such stars. Also, this allows us to overview the phenomenon of stellar magnetic activity and to study it in detail on the Still.