Electron temperature diagnostics for the quiet Sun using SI BT IV lines
Curdt, W.; Mathioudakis, M.; Keenan, F. P.; Pinfield, D. J.; Phillips, K. J. H.; Ahmed, S.
United Kingdom, Germany
Abstract
We compare SUMER observations of six Si riptsize IV emission lines detected at the quiet Sun disk centre with recent theoretical line ratio calculations. Good agreement is found between theory and observation for ratios involving the 1394, 1403 and 818 Ä line intensities. This agreement supports the theoretical prediction that the temperature where Si riptsize IV has its maximum ionisation fraction in ionisation equilibrium is T_max =~ 10(4.8) K, as well as showing that Lyman continuum absorption does not significantly effect line intensities for transitions with wavelengths below 912 Ä. We find that the 815, 1122 and 1128 Ä lines are blended by approximately 30, 55 and 45%, respectively, in the SUMER transitions.