Bulk Heating and Slender Magnetic Loops in the Solar Corona

Abstract

The heating of the solar corona and the puzzle of the slender high reaching magnetic loops seen in observations from the Transition Region and Coronal Explorer (TRACE) has been investigated through three-dimensional numerical simulations and found to be caused by the well-observed plasma flows in the photosphere displacing the footpoints of magnetic loops in a nearly potential configuration. It is found that even the small convective displacements cause magnetic dissipation sufficient to heat the corona to temperatures of the order of a million K. The heating is intermittent in both space and time—at any one height and time it spans several orders of magnitude, and localized heating causes transonic flows along field lines, which explains the observed nonhydrostatic stratification of loops that are bright in emission measure.