Coronal heating in magnetic loops
The external atmosphere of the Sun, the solar corona is at 10^6 K, two orders of magnitude higher than the surface of the Sun, the photosphere,
at 10^4K. This is the coronal heating problem.

Coronal loops as seen by TRACE in EUV

We consider magnetic loops in the solar corona, anchored in the photosphere, where flow convective motions drive the magnetic field lines due to the frozen-field line condition, as a result of the high conductivity of the coronal plasma.


               Theory model of a magnetic loop



The velocity and magnetic field of the coronal loop are governed by the MHD equations, and due to the large kinetic and magnetic Reynolds numbers in the corona, they are in a turbulent regime. We solve these equations by direct numerical simulations, based on accurate pseudospectral methods. Global energy, dissipation rate, mean currents, energy spectra and spatial distribution of currents  can be obtained. The dissipation rate is compatible to what is necessary to heat the corona (and consistent with estimations inferred from remote observations). Dissipation is intermittent and can be statistically study, obtaining distributions of energy release events (nanoflares) with a power law, similar to power laws obtained from flare observations at much larger energies, suggesting a common physical process underlying these phenomena.  



                 NanoflaresNanfolare distribution                 





       Dmitruk & Gomez, Astrophys. Jour. Lett. 1997
         Dmitruk, Gomez & DeLuca, Astrophys. Jour. 1998
         Dmitruk & Gomez, Astrophys. Jour. Lett. 1999
         Milano, Dmitruk, Gomez, Mandrini, Demoulin, Astrophys. Jour. 1999
         Gomez, Dmitruk, Milano, Solar Phys. 1999
         Dmitruk, Gomez & Matthaeus, Phys. Plasmas 2003