FE XVI LINE RATIOS IN THE SUN

Recent R-matrix calculations of electron impact excitation rates in Fe XVI are used to derive the emmission-line ratios R(1) = I(251.07 Angstrom)/I(335.40 Angstrom), R(2) = I(262.98 Angstrom)/I(335.40 Angstrom), and R(3) = I(265.00 Angstrom) /I(335.40 Angstrom). A comparison of these with solar observational data obtained by the Naval Research Laboratory's S082A slitless spectrograph on board Skylab reveals generally good agreement between theory and observation, which provides experimental support for the accuracy of the atomic data adopted in the analysis. However, several of the measured ratios are much larger than theory predicts, which is probably due to saturation of the strong 335.40 Angstrom line on the photographic film used to record the S082A data. The potential usefulness of R(1), R(2), and R(3) as electron temperature diagnostics for the solar corona is briefly discussed.