Magnetic neutral sheets in evolving fields. II. Formation of the solar corona

It is shown in the previous paper that whenever twisted flux tubes are bundled together, they are subject to dynamical nonequilibrium and internal neutral point reconnection, causing rapid dissipation of their torsion. In the present paper we explore the consequences of this general dynamical dissipation in the magnetic fields that produce the active corona of the Sun. The footpoints of the field are continually manipulated by the subphotospheric convection, so that the lines of force are continually wrapped and rotated about each other. The dynamical dissipation of the wrapping and rotation transfers the work done on the footpoints directly into heat in the corona, at a rate estimated to be of the order of 107 ergs cm-2 s-1. The effect appears to be the principal source of heat to the visible corona. This general picture implies that all magnetic fields extending outward from convecting astronomical bodies produce intense heating of the tenuous outer atmospheres of these bodies, in general agreement with the observed fact of the universal activity of stars and galaxies