Two-dimensional multi-parameter fields of a limb flare loop system

Abstract

The 2D H-beta spectral data of the post-flare loop system (PFLs) of August 17, 1989 are obtained and analyzed quantitatively. Four physical parameters (the line-of-sight velocity V-//, column number density of the hydrogen atoms at the second level along the line-of-sight direction N-2, the excitation temperature T-ex and the micro-turblence velocity V-t) and their 2D distributions are derived. The 2D fields of V-//, N-2, T-ex and V-t exhibit inhomogeneous and asymmetric properties in two loop legs. Red-shift velocities in the south leg are smaller than those of blue shift in the north leg where the velocity reaches 60 km s(-1). The values of N-2 and T-ex in the south leg are all much higher than those in the north leg, N-2 ranges between 0.5 to 4.5 x 10(13) cm(-2), while T-ex ranges from 0.8 to 2.2 x 10(4) K, lower at the top part than in the two legs. A high temperature region is located in the middle of the south leg. V-t at the top part is greater than that in the two legs, with the average being 30 similar to 40 km s(-1). Electron density n(e) and electron pressure P-e are estimated at 0.2 similar to 0.6 x 10(11) cm(-3) and at 0.04 similar to 0.12 dyn cm(-2), respectively. These results are compared with those obtained from the PFLs of 1984 February 18.