Benchmarking atomic data for the CHIANTI atomic database: coronal lines observed by Hinode EIS

Zanna, G. Del

doi:10.1051/0004-6361/201117592

Cited by 68 publications

(62 citation statements)

References 44 publications

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“…Del Zanna et al (2004) presented new identifications and a set of new observed energies that are adopted here. The energies of the 3s 2 3p 4 3d levels have all been confirmed with recent, accurate EUV observations with the Hinode EUV Imaging Spectrometer (Del Zanna 2012).…”

Section: Previous Observations and Atomic Data For Fe Xsupporting

confidence: 76%

Atomic data for astrophysics: Fe x soft X-ray lines

Zanna¹,

Storey

Badnell

et al. 2012

A&A

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New atomic calculations for Fe x are presented. They focus on the need to model the soft X-ray spectrum and in particular the line at 94.0 Å which is the dominant contribution to the Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA) 94 Å band in quiet Sun conditions. This line, and others in the band, are due to strong decays from n = 4 levels. We present new large-scale R-matrix (up to n = 4) and distorted-wave (DW, up to n = 6) scattering calculations for electron collisional excitation and compare them to earlier work. We find significant discrepancies with previous calculations. We show that resonances significantly increase the cross-sections for excitations from the ground state to some n = 4 levels, in particular to those in the 3s 2 3p 4 4s configuration. Cascading from higher levels is also important. We suggest a new identification for the 3s 3p 6 2 S 1/2 -3s 3p 5 4s 2 P 3/2 transition, that has a predicted intensity larger than the decays from the 3s 2 3p 4 4s levels which were identified by Edlén in 1936. The results presented here are relevant to our understanding of transitions from n = 4 levels in a wide range of other ions.

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Section: Previous Observations and Atomic Data For Fe Xsupporting

confidence: 76%

Atomic data for astrophysics: Fe x soft X-ray lines

Zanna¹,

Storey

Badnell

et al. 2012

A&A

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“…The corresponding response for this band was calculated by adding the Fe xiv emissivity to the continuum. The atomic data for Fe xiv are reliable (Liang et al 2010;Del Zanna 2012b) and the 211.3 Å line does not have significant temperature or density effects.…”

Section: Aia 131 åmentioning

confidence: 79%

“…The Hinode EUV Imaging Spectrometer (EIS), with its two channels (SW: 166-212 Å; LW: 245-291 Å), has provided (since 2006) AR observations in a wide range of temperatures (e.g. from all the iron ionisation stages from Fe vii to Fe xvi and above 10 MK from Fe xxiii and Fe xxiv, as presented in detail in Del Zanna 2009a;Del Zanna 2012b, 2008Del Zanna et al 2011b). We have also recently provided an in-flight calibration for EIS (Del Zanna 2013).…”

Section: Introductionmentioning

confidence: 99%

The multi-thermal emission in solar active regions

Zanna¹

2013

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We present simultaneous SDO AIA and Hinode EIS observations of the hot cores of active regions (ARs) and assess the dominant contributions to the AIA EUV bands. This is an extension of our previous work. We find good agreement between SDO AIA, EVE and EIS observations, using our new EIS calibration and the latest EVE v.3 data. We find that all the AIA bands are multi-thermal, with the exception of the 171 and 335 Å, and provide ways to roughly estimate the main contributions directly from the AIA data. We present and discuss new atomic data for the AIA bands, showing that they are now sufficiently complete to obtain temperature information in the cores of ARs, with the exception of the 211 Å band. We found that the newly identified Fe xiv 93.61 Å line is the dominant contribution to the 94 Å band, whenever Fe xviii is not present. Three methods to estimate the Fe xviii emission in this band are presented, two using EIS and one directly from the AIA data. Fe xviii emission is often present in the cores of ARs, but we found cases where it is formed at 3 MK and not 7 MK, the temperature of peak ion abundance in equilibrium. The best EIS lines for elemental abundance determination and differential emission measure (DEM) analysis are discussed. A new set of abundances for many elements are obtained from EIS observations of hot 3 MK loops. The abundances of the elements with low first ionisation potential (FIP), relative to those of the high-FIP elements, are found to be enhanced by about a factor of three, compared to the photospheric values. A measurement of the path length implies that the absolute abundances of the low-FIP elements are higher than the photospheric values by at least a factor of three. We present a new DEM method customised for the AIA bands, to study the thermal structure of ARs at 1 resolution. This was tested on a few ARs, including one observed during the Hi-C rocket flight. We found excellent agreement between predicted and observed AIA count rates and EIS radiances. Overall we found few differences between the AIA and Hi-C 193 Å images of coronal structures, despite the higher Hi-C resolution (0.25 ). The Hi-C images and the AIA DEM modelling suggest that some of the cooler loops (below 1 MK) are already resolved by AIA, while the hotter (1.5-2.5 MK) "background" emission is in most places still unresolved even at the Hi-C resolution. This unresolved emission is significantly lower than previously observed with TRACE, the SOHO CDS, and Hinode EIS spectrometers. Its enhancement appears to be mostly due to increased iron abundance. We find an ubiquitous presence of emission at different temperatures that is not co-spatial, and suggest that future high-resolution imaging is carried out with isothermal bands.

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“…Young et al 2009) that these diagnostics produce higher densities than those obtained with other ions formed close in temperature. A full benchmark of the coronal density diagnostics available to Hinode EIS was performed by Del Zanna (2012), where these inconsistencies, although not very large, were confirmed. We therefore aim to investigate whether a larger calculation can resolve these discrepancies.…”

Section: Introductionmentioning

confidence: 95%

Atomic data for astrophysics: Fe xii soft X-ray lines

Zanna¹,

Storey

Badnell³

et al. 2012

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We present new large-scale R-matrix (up to n = 4) and distorted-wave (DW, up to n = 6) scattering calculations for electron collisional excitation of Fe xii. The first aim is to provide accurate atomic data for the soft X-rays, where strong decays from the n = 4 levels are present. As found in previous work on Fe x, resonances attached to n = 4 levels increase the cross-sections for excitations from the ground state to some n = 4 levels, when compared to DW calculations. Cascading from higher levels is also important. We provide a number of models and line intensities, and list a number of strong unidentified lines. The second aim is to assess the effects of the large R-matrix calculation on the n = 3 transitions. Compared to our previous (n = 3) R-matrix calculation, we find overall excellent agreement to within a few percent, however a few key density diagnostic EUV intensities differ by about 60% at coronal densities. The new atomic data result in lower electron densities, resolving previous discrepancies with solar observations.

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Benchmarking atomic data for the CHIANTI atomic database: coronal lines observed by Hinode EIS

Cited by 68 publications

References 44 publications

Atomic data for astrophysics: Fe x soft X-ray lines

Atomic data for astrophysics: Fe x soft X-ray lines

The multi-thermal emission in solar active regions

Atomic data for astrophysics: Fe xii soft X-ray lines

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