Published online by Cambridge University Press: 12 April 2016
Complementarity of solar and stellar observations should increase our knowledge of the basic facts and mechanismsof activity. The great development of stellar activity observations has enhanced theoretical study, most of which is in the framework of dynamo theory.
Even if dynamo theory seems plausible and successful in capturing the essential processes, several uncertainties and intrinsic limits do still exist and are discussed here together with alternative or complementary suggestions.