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

Zanna, G. Del; Storey, P. J.; Badnell, N. R.; Mason, H. E.

doi:10.1051/0004-6361/201219023

Cited by 43 publications

(33 citation statements)

References 28 publications

(34 reference statements)

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“…We have found the same issues we discovered in Fe x (Del Zanna et al 2012b) and found to be present in Fe xii (Del Zanna et al 2012a) and Fe xiii (Del Zanna & Storey 2012), i.e. resonance enhancement for some n = 4 configurations and levels is significant.…”

Section: Discussionsupporting

confidence: 86%

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

Zanna¹,

Storey

2012

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We present new large-scale R-matrix (up to n = 4) and distorted wave (up to n = 6) scattering calculations for electron collisional excitation of Fe xi. These data are needed for the analysis of soft X-ray spectra of astrophysical plasmas, where strong n = 4 → n = 3 transitions are present. As found in previous work on Fe x, Fe xii, and Fe xiii, resonances from within the n = 4 levels and cascading from higher levels significantly increase the intensities of these lines. We provide a list of the strongest lines, many of which are unidentified. The present larger model produces intensities for decays from n = 3 levels mostly consistent with our previous work, however significant enhancements for some lower levels are found, in particular for the 3s 2 3p 3 3d 5 D which can be used to measure electron temperatures in the solar corona with the Hinode/EIS spectrometer.

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Section: Discussionsupporting

confidence: 86%

“…The importance of resonance effects for the n = 4 levels was found when calculating atomic data for Fe x (Del Zanna et al 2012b), but was also found in Fe xii (Del Zanna et al 2012a) and Fe xiii . Here, we present new large-scale scattering calculations for the Fe xi soft X-ray lines.…”

Section: Introductionmentioning

confidence: 89%

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

Zanna¹,

Storey

2012

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“…For the Fe ions, the diagnostics are complicated further by the strong density sensitivity of many of the Fe emission lines. Although it was found that many of the standard EIS density diagnostics (e.g., Young et al, 2009;Watanabe et al, 2009;Del Zanna et al, 2012) do not depend strongly on κ or T , the uncertainties on the density measurements are passed on to the κ determinations, leading to greater uncertainty in derived values. Fe XVII was identified as the most useful Fe ion as the line ratios are insensitive to density, but the diagnostics were hampered by uncertainties in the atomic data.…”

Section: Diagnostics From Coronal Linesmentioning

confidence: 99%

Nonequilibrium Processes in the Solar Corona, Transition Region, Flares, and Solar Wind (Invited Review)

et al. 2017

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We review the presence and signatures of the non-equilibrium processes, both non-Maxwellian distributions and non-equilibrium ionization, in the solar transition region, corona, solar wind, and flares. Basic properties of the non-Maxwellian distributions are described together with their influence on the heat flux as well as on the rates of individual collisional processes and the resulting optically thin synthetic spectra. Constraints on the presence of highenergy electrons from observations are reviewed, including positive detection of non-Maxwellian distributions in the solar corona, transition region, flares, and wind. Occurrence of non-equilibrium ionization is reviewed as well, especially in connection to hydrodynamic and generalized collisional-radiative modelling. Predicted spectroscopic signatures of non-equilibrium ionization depending on the assumed plasma conditions are summarized. Finally, we discuss the future remote-sensing instrumentation that can be used for detection of these non-equilibrium phenomena in various spectral ranges.

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“…Liang et al 2009Liang et al , 2010Liang et al , 2012O'Dwyer et al 2012;Del Zanna et al 2010, 2012aDel Zanna 2011a,b;Del Zanna et al 2012b;, 2013Del Zanna et al 2014). These calculations represent significant improvements to previous atomic data, since they include a large number of levels and the associated cascading and resonances.…”

Section: Introductionmentioning

confidence: 92%

“…(4)) for each ion are also provided (Del Zanna et al 2014, 2012aDel Zanna & Storey 2013;Del Zanna et al 2010, 2012b). …”

Section: Collision Strengths Datasetsmentioning

confidence: 99%

Signatures of the non-Maxwellianκ-distributions in optically thin line spectra

Dudík¹,

Zanna²,

Mason³

et al. 2014

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Aims. We investigate the possibility of diagnosing the degree of departure from the Maxwellian distribution using single-ion spectra originating in astrophysical plasmas in collisional ionization equilibrium.Methods. New atomic data for excitation of Fe ix -Fe xiii are integrated under the assumption of a κ-distribution of electron energies.Diagnostic methods using lines of a single ion formed at any wavelength are explored. Such methods minimize uncertainties from the ionization and recombination rates, as well as the possible presence of non-equilibrium ionization. Approximations to the collision strengths are also investigated.Results. The calculated intensities of most of the Fe ix -Fe xiii EUV lines show consistent behaviour with κ at constant temperature.Intensities of these lines decrease with κ, with the vast majority of ratios of strong lines showing little or no sensitivity to κ. Several of the line ratios, especially involving temperature-sensitive lines, show a sensitivity to κ that is of the order of several tens of per cent, or, in the case of Fe ix, up to a factor of two. Forbidden lines in the near-ultraviolet, visible, or infrared parts of the spectrum are an exception, with smaller intensity changes or even a reverse behaviour with κ. The most conspicuous example is the Fe x 6378.26 Å red line, whose intensity incerases with κ. This line is a potentially strong indicator of departures from the Maxwellian distribution. We find that it is possible to perform density diagnostics independently of κ, with many Fe xi, Fe xii, and Fe xiii line ratios showing strong density-sensitivity and negligible sensitivity to κ and temperature. We also tested different averaging of the collision strengths. It is found that averaging over 0.01 interval in log(E [Ryd]) is sufficient to produce accurate distribution-averaged collision strengths Υ(T, κ) at temperatures of the ion formation in ionization equilibrium.

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

Cited by 43 publications

References 28 publications

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

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

Nonequilibrium Processes in the Solar Corona, Transition Region, Flares, and Solar Wind (Invited Review)

Signatures of the non-Maxwellianκ-distributions in optically thin line spectra

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