An observational test for coronal heating models

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

Sydney, Australia

Simposio; IAU Symposium 219; 2004

IAU

We correlate the evolution of the mean X-ray flux emission measure and temperature (Yohkoh SXT & BCS) with the magnetic flux density (SOHO/MDI) in active region NOAA 7978 from its birth throughout its decay for five solar rotations. We show that these plasma parameters together with other quantities deduced from them such as the density and the pressure follow power-law relationships with the mean magnetic flux density (bar{B}). We derive the dependence of the mean coronal heating rate on the magnetic flux density. We use the obtained scaling laws of coronal loops in thermal equilibrium to derive observational estimates of the scaling of the coronal heating with bar{B}. These results are used to test the validity of coronal heating models. We find that models invoking stochastic buildup of energy current layers and MHD turbulence are in best agreement with the observations. This narrows down the range of possible models retained by previous results obtained for individual coronal loops as well as for the global coronal emission of the Sun and cool stars.