The plasma and magnetic field properties of coronal loops observed at high spatial resolution

Abstract

Two data sets are analyzed in order to improve understanding of the plasma and magnetic field properties of active region coronal loops. Each set consists of coaligned, high spatial resolution soft X-ray, microwave, and magnetogram images that are used to compare observations of coronal loops and their feet in the photosphere and to constrain possible microwave emission mechanisms. The loops are found to have plasma parameters typical of quiescent active region loops. Each loop has a compact microwave source with peak brightness temperature T(b) = 1-2.5 x 10 to the 6th K cospatial with or near the loop apex. No complete loops are imaged in microwaves. The loop emission observed at 4.9 GHz is best described by fourth harmonic gyroresonance emission from a dipole loop model, but with less field variation along the loop than in the models of Holman and Kundu (1985).