On the origin of sunspots

It is proposed that sunspots (and other flux emergence phenomena) originate due to the presence of fluctuating magnetic fields in addition to the regular, mean field in the convection zone. The mean field predicted by dynamo theories is too weak by itself to emerge at the surface of the Sun. However, the same dynamoprocesses that produce themeanfield also produce fluctuating fields. It is suggested here that magnetic fields emerge at the solar surface at those random times and places when the total magnetic field (mean field plus fluctuations) exceeds the threshold for buoyancy. In this way the mean field is responsible for observed regularities of the sunspot magnetic fields, such as theHale’s law and the 11-year periodicity, and the fluctuations are responsible for emergence of the magnetic field of individual sunspots. A simple illustrative model calculation of a series of ”sunspot cycles” is presented. Themodel spectrum compares well with the observed spectrum of sunspots.