AL IX EMISSION-LINE RATIOS IN SOLAR-FLARES OBSERVED WITH THE S082A SPECTROGRAPH ON BOARD SKYLAB

Theoretical electron-density-sensitive emission line ratios in B-like Al IX are presented for R = I(385.01 angstrom)/I(392.42 angstrom). A c omparison of these with high spectral resolution solar flare data, obt ained with the S082A slitless spectrograph on board Skylab, reveals ag reement between theory and observation for those spectra that were obs erved during the later stages of the flares. These results provide exp erimental support for the accuracy of the line-ratio calculations, and also resolves discrepancies found previously when the theoretical res ults were compared with solar observations from the S-055 instrument o n board Skylab. However, the agreement between theory and observation for a spectrum obtained during the early stages of a flare is very poo r, which probably indicates that the 392.42 angstrom line is blended w ith a transition arising from a species formed at a very high electron temperature.