G. Del Zanna (DAMTP, Centre for Mathematical Sciences, Wilberforce Road, Cambridge, CB3 0WA, UK)
A collection of the best solar and laboratory spectra in the soft X-rays is used here to perform a preliminary benchmark in this wavelength region, by comparing observed vs. predicted wavelengths and calibrated solar irradiances. The benchmark focuses on the Fe IX – Fe XIV ions,for which we have recently calculated the relevant atomic data, however a few other ions have also been benchmarked. The iron ions are dominating the soft X-rays, however a large fraction of the strongest soft X-ray lines due to n=4 -> n=3 transitions were previously unidentified. The strongest transitions are all identified here, in particular the decays from the core-excited levels (3s 3p^l 4s, l= 5,4,3,2,1 for Fe X, Fe XI, Fe XII, Fe XIII, and Fe XIV respectively) which are the strongest soft X-ray transitions from these ions. Many new identifications are proposed, some only tentatively. Good agreement in terms of solar irradiances between the soft X-ray and EUV (n=3 -> n=3) transitions is found, confirming the reliability of the new large-scale calculations. Some of the new atomic data and identifications are particularly important for the Solar Dynamic Observatory (SDO) Atmospheric Imaging Assembly (AIA) 94 A band.
Complete preprint ==> http://arxiv.org/abs/1208.2142