Atomic data from the IRON Project

Witthoeft, M. C.; Badnell, N. R.

doi:10.1051/0004-6361:20079073

Cited by 31 publications

(47 citation statements)

References 15 publications

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“…In the past few years, we (the APAP team 1 ) have produced a significant amount of new large-scale atomic calculations for a large number of ions, including Fe vii (Witthoeft & Badnell 2008) (Liang et al 2010), and Fe xvi (Liang et al 2009). The R-matrix calculations for Fe x-Fe xiii were not trivial, and a lot of surprising issues were found.…”

Section: Atomic Data and Instrument Calibrationsmentioning

confidence: 99%

The multi-thermal emission in solar active regions

Zanna¹

2013

A&A

159

110

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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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Section: Atomic Data and Instrument Calibrationsmentioning

confidence: 99%

The multi-thermal emission in solar active regions

Zanna¹

2013

A&A

159

110

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“…For Fe +5 we use a 19 level atom with transition probabilities and collision strengths from Chen & Pradhan (1999. Finally, for Fe +6 we use a 9 level atom with transition probabilities and collision strengths from Witthoeft & Badnell (2008). Energy levels are those listed in the NIST Atomic Spectra Database 4 ; the Hβ emissivities are based on the empirical formula by Aller (1984 We used all the lines listed above which are not affected or suspected of blends and misidentifications to derive ionic abundances in these four PNe.…”

Section: Total Abundances Without An Icfmentioning

confidence: 99%

C/O Abundance Ratios, Iron Depletions, and Infrared Dust Features in Galactic Planetary Nebulae

Delgado-Inglada

Rodríguez

2014

ApJ

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We study the dust present in 56 Galactic planetary nebulae (PNe) through their iron depletion factors, their C/O abundance ratios (in 51 objects), and the dust features that appear in their infrared spectra (for 33 objects). Our sample objects have deep optical spectra of good quality, and most of them also have ultraviolet observations. We use these observations to derive the iron abundances and the C/O abundance ratios in a homogeneous way for all the objects. We compile detections of infrared dust features from the literature and we analyze the available Spitzer/IRS spectra. Most of the PNe have C/O ratios below one and show crystalline silicates in their infrared spectra. The PNe with silicates have C/O < 1, with the exception of Cn 1-5. Most of the PNe with dust features related to C-rich environments (SiC or the 30 μm feature usually associated to MgS) have C/O 0.8. Polycyclic aromatic hydrocarbons are detected over the full range of C/O values, including 6 objects that also show silicates. Iron abundances are low in all the objects, implying that more than 90% of their iron atoms are deposited into dust grains. The range of iron depletions in the sample covers about two orders of magnitude, and we find that the highest depletion factors are found in C-rich objects with SiC or the 30 μm feature in their infrared spectra, whereas some of the O-rich objects with silicates show the lowest depletion factors.

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“…The contribution function, G(T e , N e ), contains the relevant atomic parameters for each line and can be obtained using equilibrium ionisation balance calculations. For this purpose we have used CHIANTI v7.1 (Dere et al 1997;Landi et al 2013) together with new atomic data for Fe VII (Witthoeft & Badnell 2008;Del Zanna 2009 Landi et al 2012) in terms of ions which contribute significantly to the XRT channels. The quantity ϕ(T e ) is known as the differential emission measure (DEM) which is defined as…”

Section: Observations and Data Analysismentioning

confidence: 99%

Response of Hinode XRT to quiet Sun, active region and flare plasma

O’Dwyer¹,

Zanna²,

Mason³

2013

A&A

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Aims. We examine the response of the Hinode X-Ray Telescope (XRT), using simultaneous observations with the Hinode Extremeultraviolet Imaging Spectrometer (EIS), for a flare, an active region and a quiet Sun region. We also examine the relative intensity calibration of EIS and XRT. Methods. EIS differential emission measure distribution (DEM) curves were used to create synthetic spectra with the CHIANTI atomic database. The contribution of spectral lines and continuum emission to each of the XRT channels was determined from the synthetic spectra, which were then convolved with the effective area of each XRT channel. The predicted total count rates for each channel were compared with the observed count rates. The effects of varying elemental abundances and the temperature range for the inversion were investigated. DEMs obtained from the XRT bands were also computed and compared to those obtained with EIS.Results. For the active region observations, the observed XRT count rates for most of the channels are in reasonable agreement with those predicted using EIS observations, but are dependent on the elemental abundances chosen. Significant discrepancies between predicted and observed count rates were found and are discussed for the adjacent quiet Sun region and also for the flare. Synthetic spectra and continuum emission contributing to the XRT channels are presented and discussed for the active region, quiet Sun and flare observations.

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Atomic data from the IRON Project

Cited by 31 publications

References 15 publications

The multi-thermal emission in solar active regions

The multi-thermal emission in solar active regions

C/O Abundance Ratios, Iron Depletions, and Infrared Dust Features in Galactic Planetary Nebulae

Response of Hinode XRT to quiet Sun, active region and flare plasma

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