Abstract:
The heating of the solar corona to million-degree temperatures is a central problem of solar physics. A neat MHD calculation is presented to illustrate Parker's theory of spontaneous formation of electric current sheets in a magnetic field under conditions of perfect electrical conductivity. The conductivity of an astrophysical plasma may be extremely large but never infinite. Therefore, current sheets do form in it except that they naturally dissipate into heat by its small but finite electrical resistivity. This mode of current dissipation offers an attractive explanation for the hot solar corona embedding a global magnetic field of about 10 Gauss. The physical idea of this mathematical theory will be described in terms of an interesting MHD relationship between the existence of continuous equilibrium for a magnetic field and its field topology.
Coffee and tea will be served 20 minutes prior to the seminar.