CHIANTI - An atomic database for emission lines. XI. EUV emission lines of Fe VII, Fe VIII and Fe IX observed by Hinode-EIS - Astrophysics > Solar and Stellar AstrophysicsReportar como inadecuado




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Abstract: A detailed study of emission lines from Fe VII, Fe VIII and Fe IX observed bythe EUV Imaging Spectrometer on board the Hinode satellite is presented.Spectra in the ranges 170-212 A and 246-292 A show strongly enhanced lines fromthe upper solar transition region temperatures 5.4 <= log T <= 5.9 allowing anumber of new line identifications to be made. Comparisons of Fe VII lines withpredictions from a new atomic model reveal new plasma diagnostics, howeverthere are a number of disagreements between theory and observation for emissionline ratios insensitive to density and temperature, suggesting improved atomicdata are required. Line ratios for Fe VIII also show discrepancies with theory,with the strong 185.21 and 186.60 lines under-estimated by 60-80 % compared tolines between 192 and 198 A. A newly-identified multiplet between 253.9 and255.8 A offers excellent temperature diagnostic opportunities relative to thelines between 185-198 A, however the atomic model under-estimates the strengthof these lines by factors 3-6. Two new line identifications are made for Fe IXat wavelengths 176.959 A and 177.594 A, while seven other lines between 186 and200 A are suggested to be due to Fe IX but for which transition identificationscan not be made. The new atomic data for Fe VII and Fe IX are demonstrated tosignificantly modify models for the response function of the TRACE 195 Aimaging channel, affecting temperature determinations from this channel. Thedata will also affect the response functions for other solar EUV imaginginstruments such as SOHO-EIT, STEREO-EUVI and the upcoming AIA instrument onthe Solar Dynamics Observatory.



Autor: P.R. Young, E. Landi

Fuente: https://arxiv.org/







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