Benchmarking atomic data for astrophysics: Fe XVII X-ray lines

Abstract

Recent R-matrix scattering calculations for electron impact excitation of Fe xvii are benchmarked against various X-ray solar observations. Quiescent active region observations are considered, together with a few SMM/FCS observations of active regions and flares analysed here. Extremely good agreement (within 10%) between expected and measured line intensities is found, with the exception of a few weaker lines that appear to be blended, and without the need to invoke opacity effects in the stronger line. The long-standing discrepancies that have been present when distorted wave (DW) calculations are adopted are now finally resolved. As was shown in the Fe xviii case, the differences with the DW calculations are caused by resonances that significantly increase the collision strengths of the 2p-3s transitions. The strong Fe xvii lines can now be reliably used to measure electron temperatures in the solar corona and other astrophysical sources. Emission measure modelling with the most recent atomic data of quiescent active region cores indicates O/Fe and Ne/Fe abundances reduced by factors of two to four compared to the latest compilation of "photospheric" abundances.

Solar UV and X-ray spectral diagnostics

“…As shown by Del Zanna (2011b), the discrepancies in astrophysical observations were finally resolved with the Liang and Badnell (2010) data, although the Breit–Pauli R -matrix calculations of Loch et al. (2006) also showed good agreement with observation.…”

“…The identifications of the strongest XUV lines of the most important iron ions have been assessed in a series of benchmark papers, where a significant number of new identifications have been proposed, and where detailed references to previous original identifications can be found: Fe vii (Del Zanna 2009a), Fe viii (Del Zanna 2009b), Fe ix (Del Zanna 2009a), Fe x (Del Zanna et al. 2004a), Fe xi (Del Zanna 2010), Fe xii (Del Zanna and Mason 2005a), Fe xiii (Del Zanna 2011a), Fe xvii (Del Zanna and Ishikawa 2009; Del Zanna 2011b), Fe xviii (Del Zanna 2006a), Fe xxiii (Del Zanna et al. 2005), Fe xxiv (Del Zanna 2006b).…”

Electron-correlation effects on the3Cto3Dline-intensity ratio in the Ne-like ionsAr8+Santana1, Lepson2, Beiersdörfer3 2015Phys. Rev. A305210View full textAdd to dashboardCite

“…The resonance-to-intercombination line intensity ratio in Fe 16+ , the so called 3C/3D line ratio, has been the focus of many experimental [1][2][3][4][5][6][7][8] and theoretical studies [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. The large amount of work has been stimulated, on one side, by the potential application of these lines as diagnostics of astrophysical plasmas [4,[29][30][31], and on the other, by the unexpected deviation between the measured and the theoretical 3C/3D line ratio [1,6,8,27,28].…”

AtomPy: An Open Atomic Data Curation Environment for Astrophysical Applications

“…It must be mentioned that cohesiveness between atomic data producers and users has not been easy to broker in the past, in spite of periodic international conferences such as ICAMDATA [37], joint symposia (e.g., the Tenerife meeting in October 2010 on "Uncertainties in atomic data and how they propagate in chemical abundances" [38,39]), capacity development schools (e.g., NebulAtom [40]), and the AstroAtom blog [41]. However, there are exceptions to this inherent detachment, in particular the extensive astrophysical benchmarks that have been carried out of iron EUV and X-ray lines for the CHIANTI database [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56]. …”