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

¹ Yunnan Observatory, CAS, Kunming 650011 and National Astronomical Observatories, CAS, Beijing 100012, PR China
² United Laboratory of Optical Astronomy, CAS, Shanghai 200030, PR China

Corresponding author: Xiao Ma Gu, ssg@public.km.yn.cn

Received: 20 November 2000
Accepted: 7 August 2001

Abstract

The 2D H 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 N₂, the excitation temperature T_ex and the micro-turblence velocity V_t) and their 2D distributions are derived. The 2D fields of V_//, N₂, 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 N₂ and T_ex in the south leg are all much higher than those in the north leg, N₂ ranges between 0.5 to cm^-2, while T_ex ranges from 0.8 to 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 30~40 km s^-1. Electron density n_e and electron pressure P_e are estimated at 0.2~ cm^-3 and at 0.04~0.12 dyn cm^-2, respectively. These results are compared with those obtained from the PFLs of 1984 February 18.