Relation between thermal and magnetic properties of active regions as a probe of coronal heating mechanisms

We study the relation between thermal and magnetic properties of active reg ions in the corona observed with the soft X-ray telescope aboard Yohkoh. We derive the mean temperature and pressure of 64 mature active regions using the filter ratio technique, and examine the relationship of region size wi th temperature and pressure. We find that the temperature T of active regio ns increases with increasing region size L as T proportional to L-0.28, whi le the pressure, We P slightly decreases with the region size as P proporti onal to L-0.16. We confirm the scaling law T proportional to (PL)(1/3) for mature active regions found by R. Rosner, W. H. Tucker, & G. S. Vaiana. We examined the magnetic properties of active regions by analyzing 31 active r egions observed with the Solar and Heliospheric Observatory/Michelson Doppl er Imager and find the following empirical scaling law between thermal and magnetic properties, U-th proportional to Phi (1.33), P proportional to B-0.78, where U-th, Phi, and B are the total thermal energy content, total magnetic flux, and average magnetic flux density of active regions, respectively. T he former is consistent with the results of L. Golub et al., but the latter is not. Implications of our findings for coronal heating mechanisms are di scussed.