NIFS-396

FULL TEXT (PDF, 1177 KB)


Author(s):

T. Kato, T. Fujiwara and Y. Hanaoka

Title:

X-ray Spectral Analysis of Yohkoh BCS Data on Sep. 6 1992 Flares
- Blue Shift Component and Ion Abundances -

Date of publication:

Feb. 1996

Key words:

solar flares, X-ray spectroscopy, ion abundance, solar abundance, He-like ions

Abstract:

We have studied the time evolution of BCS spectra of He - like S XV, Ca XIX and Fe XXV ions observed by the Yohkoh satellite for solar flares on 6th September 1992 at 05:05 (M2.4 class) and 08:59(M3.3 class). Electron temperatures are derived through the fit of the synthetic spectra to the observed ones. Apparent ion temperatures are derived from the line width of S XV and Ca XIX spectra. The blue shifted component in the rising phase is separated from the main component of the Ca XIX spectra. The emission measures are derived from the spectra without assuming ionization equilibrium and solar abundances for the first time. The time variation of these parameters are compared with hard X-rays, soft X-rays and radio measurements. In the preheating phase, the moderate increase of thermal plasma with turbulence indicated from the line width is observed. The time evolution of the blue shift component coincides with that of the burst in hard X-rays and microwaves which are produced by non - thermal high energy electrons. The ion density ratios derived from the spectra show a time -dependent non equilibrium ionization. They are shifted from the equilibrium values indicating an ionizing plasma.

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