A comparison of theoretical and solar-flare intensity ratios for the Fe XIX X-ray lines

Atomic data including energy levels, gf-values, and wavelengths are given for the Fe XIX transitions that give rise to lines in solar-flare and active-region X-ray spectra. Collision strengths and theoretical intensity ratios are presented for lines which occur in the 13.2-14.3-A range. Observed spectra are found to be consistent with those derived from the present Fe XIX atomic data. For the case of spectra in which the Fe XIX lines are very strong, such as those at the maxima of hot flares, two observed line features due to Fe XIX are shown to have larger intensities than calculated. The calculated Fe XIX and Ne IX line spectra are used to determine electron densities from Ne IX line ratios.