2009A&A...508..513D -
Astronomy and Astrophysics, volume 508, 513-524 (2009/12-2)
Benchmarking atomic data for astrophysics: Fe VIII EUV lines.
DEL ZANNA G.
Abstract (from CDS):
The EUV spectrum of FeVIII is reviewed, using new solar observations from the Hinode EUV Imaging Spectrometer (EIS), together with older solar and laboratory data. The most up-to-date scattering calculations are benchmarked against these experimental data, with the use of a large atomic structure calculation. Once adjustments are made to the excitation rates, good agreement is found between calculated and observed line intensities. All previous line identifications have been re-assessed. Several lines are identified here for the first time, most notably the strong decays from the 3s2 3p5 3d2 4Dj levels. It is shown that they provide a new, important diagnostic of electron temperature for the upper transition region. The temperatures obtained at the base of solar coronal loops are lower (logT[K]=5.5) than those predicted by assuming ionization equilibrium (logT[K]=5.6), however firm measurements will only be possible once better scattering calculations are available, and the EIS radiometric calibration is properly assessed.
Abstract Copyright:
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Journal keyword(s):
line: identification - atomic data - Sun: transition region - techniques: spectroscopic
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