SI(XIII) EMISSION-LINES IN SOLAR-FLARE X-RAY-SPECTRA OBTAINED WITH THE P78-1 SATELLITE

Theoretical Si XIII electron-temperature-sensitive emission-line ratio s, which include satellite-line contributions to the intensities of th e forbidden (f) 1s2 1S-1s2s 3S, intercombination (i) 1s2 1S-1s2p P-3(1 ,2), and resonance (r) 1s2 1S-1s2p 1P transitions, are presented for G = [I(f) + I(i)]/I(r), R = I(f)/I(i), R1 = I(1s2 1S-1s3p 1P)/I(r), and R2 = I(1s2 1S-1s4p 1P)/I(r). These ratios are significantly different , from those calculated assuming that satellites do not contribute to f, i, and r, and, in addition, are more temperature-sensitive over the range log T(e) = 6.4-7.4. Electron temperatures deduced using the new diagnostics in conjunction with observed values of G, R1, and R2, fro m solar-flare spectra obtained by the SOLEX spectrometers aboard the P 78-1 satellite are found to be generally consistent. This provides sup port for the validity of the theoretical R1 and R2 diagnostics and als o resolves discrepancies noted previously when the line ratios were co mpared with observations from the Solar Maximum Mission spectrometers. The R ratio, which is in the low-density limit under solar flare cond itions, is found not to be a useful T(e) diagnostic when satellite con tributions to f and i are included in the theoretical line ratios. How ever, the observed values of R from the SOLEX spectra are in good agre ement with theoretical predictions, which provides additional support for the accuracy of the line-ratio calculations.