Atomic data for astrophysics: Fe xi soft X-ray lines

Abstract

We present new large-scale R-matrix (up to n=4) and distorted wave (up to n=6) scattering calculations for electron collisional excitation of Fe xi. These data are needed for the analysis of soft X-ray spectra of astrophysical plasmas, where strong n=4→n=3 transitions are present. As found in previous work on Fe-x, Fe xii, and Fe xiii, resonances from within the n=4 levels and cascading from higher levels significantly increase the intensities of these lines. We provide a list of the strongest lines, many of which are unidentified. The present larger model produces intensities for decays from n=3 levels mostly consistent with our previous work, however significant enhancements for some lower levels are found, in particular for the 3s2 3p3 3d 5D which can be used to measure electron temperatures in the solar corona with the Hinode/EIS spectrometer. © 2012 ESO.