S-XI LINE RATIOS IN THE SUN

Theoretical S XI electron density sensitive emission-line ratios are p resented for R1 = I(2s(2)2p2 1D-2s2p3 1D)/I(2s(2)2p2 P-3(2)-2s2p3 3S) = I(215.97 angstrom)/I(191.29 angstrom) and R2 = I(2s(2)2p2 1D-2s2p3 P -1)/I(2s(2)2p P-3(2)-2s2p3 3S) = I(190.37 angstrom)/I(191.29 angstrom) . A comparison of these with solar flare observational data from the N aval Research Laboratory's S082A spectrograph on board Skylab reveals that the experimental ratios are generally much larger than expected f rom theory, which is probably due to blending of the S XI 215.97 angst rom line with Ni XVII 215.91 angstrom, and S XI 190.37 angstrom with a n unidentified feature at a coincident wavelength. These observations indicate that photoexcitation of S XI by Fe XIII 191.26 angstrom is pr obably not an important process in the solar atmosphere under flare co nditions, as it would lead to a significant enhancement of the S XI 19 1.29 angstrom line, and hence observed values of R1 and R2 that are sm aller than theory predicts.