New atomic data for the FeXII coronal ion

Abstract

Various FeXII spectroscopic lines in the UV and EUV range have been proved to be ideal diagnostic tools for measuring electron temperature, density and iron abundance in the solar corona. In the framework of the “IRON PROJECT” we have provided improved theoretical calculations of the atomic data required to analyse the intensity of these lines and to apply the results to SOHO (Solar Heliospheric Observatory) observations. Extensive configuration interaction and relativistic effects have been allowed for in the atomic structure computations which have provided energy levels and an extensive set of radiative data. The e-FeXII collisional problem has been tackled with the multichannel R-matrix method, a close-coupling calculation for the determination of electron impact collision strengths. Final results are presented for FeXII thermally averaged collision strengths, for fine-structure forbidden transitions within the ground configuration.