The solar coronal X-ray spectrum from 5.5 to 12 A

A compilation of spectral lines in the 5.5-12 A wavelength region is presented from observations under a variety of solar conditions, including flare onset, flares, and nonflaring active regions. The line fluxes and wavelengths of Fe XXII-XXIV are compared with theory, and the results for Fe XXIII-XXIV are shown to agree with theoretical determinations. When only the strongest lines are considered, some relative strengths agree with theory and some do not. Diagnostically useful line ratios of Mg XI, Al XII, and Si XIII are also examined. The density-sensitive line ratio R measured for Mg XI and Si XIII agree with theoretical calculations of R(0) the low-density limit of R. For Mg XI in a flare-onset spectrum, R is lower than R(0), but the statistical significance of the result is not high.