How to test coronal heating models?

MANDRINI, C.H.; DÉMOULIN, P.; VAN DRIEL-GESZTELYI, L.; KLIMCHUK, J.A.; HARRA, L.K.

La Plata

Congreso; 46 Reunión Anual de la Asociación Argentina de Astronomía; 2003

Asociación Argentina de Astronomía

We have tested coronal heating models following two different approaches. In the first case, we compared the dependence of the coronal heating rate predicted by theoretical models with the observed one, deriving the scalings of parameters, such as: the density, temperature and intensity of the coronal magnetic field, with the length of magnetic field lines. To do so, we combined density and temperature measurements for 47 coronal loops with magnetic field models for 14 active regions. In the second case, we analyzed the long term evolution of an active region observed during seven rotations on the solar disk and we determined the dependence of the observed heating rate with the magnetic field density (bar{B}), after finding the scalings of plasma parameters with bar{B}. In both cases, we found that models based on the dissipation of stressed, current-carrying magnetic fields (called direct current models) are in better agreement with observations than models that attribute coronal heating to the dissipation of MHD waves injected at the base of the corona (called alternate current models). Taking into account that the photospheric field is concentrated in thin magnetic flux tubes, observations are in best agreement with models invoking a stochastic buildup of energy, current layers and MHD turbulence, within direct current models.