Atomic data for astrophysics: Ni XII

Zanna, G. Del; Badnell, N. R.

doi:10.1051/0004-6361/201527378

Cited by 11 publications

(10 citation statements)

References 45 publications

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“…The largest scattering calculation for this ion is the APAP ICFT R -matrix one by Del Zanna and Badnell (2016b), which included levels up to . With the exception of the three strongest soft X-ray transitions, large differences with previous calculations are found, mainly affecting the decays from the lowest levels and the forbidden UV lines.…”

Section: Atomic Calculations and Datamentioning

confidence: 99%

Solar UV and X-ray spectral diagnostics

Zanna

Mason

2018

Living Rev Sol Phys

213

139

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X-ray and ultraviolet (UV) observations of the outer solar atmosphere have been used for many decades to measure the fundamental parameters of the solar plasma. This review focuses on the optically thin emission from the solar atmosphere, mostly found at UV and X-ray (XUV) wavelengths, and discusses some of the diagnostic methods that have been used to measure electron densities, electron temperatures, differential emission measure (DEM), and relative chemical abundances. We mainly focus on methods and results obtained from high-resolution spectroscopy, rather than broad-band imaging. However, we note that the best results are often obtained by combining imaging and spectroscopic observations. We also mainly focus the review on measurements of electron densities and temperatures obtained from single ion diagnostics, to avoid issues related to the ionisation state of the plasma. We start the review with a short historical introduction on the main XUV high-resolution spectrometers, then review the basics of optically thin emission and the main processes that affect the formation of a spectral line. We mainly discuss plasma in equilibrium, but briefly mention non-equilibrium ionisation and non-thermal electron distributions. We also summarise the status of atomic data, which are an essential part of the diagnostic process. We then review the methods used to measure electron densities, electron temperatures, the DEM, and relative chemical abundances, and the results obtained for the lower solar atmosphere (within a fraction of the solar radii), for coronal holes, the quiet Sun, active regions and flares.

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Section: Atomic Calculations and Datamentioning

confidence: 99%

Solar UV and X-ray spectral diagnostics

Zanna

Mason

2018

Living Rev Sol Phys

213

139

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“…The high computational power reachable nowadays allows calculating energies and collision strengths for groups of ions with the same iso-sequence [e.g. [76][77][78][79], or the same type of transitions for all ions [80]. As different codes calculate new sets of data as well as fit spectra (e.g.…”

Section: Correcting Heavy-element Energy Levelsmentioning

confidence: 99%

Challenges and Techniques for Simulating Line Emission

et al. 2018

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Modeling emission lines from the millimeter to the UV and producing synthetic spectra is crucial for a good understanding of observations, yet it is an art filled with hazards. This is the proceedings of "Walking the Line", a 3-day conference held in 2018 that brought together scientists working on different aspects of emission line simulations, in order to share knowledge and discuss the methodology. Emission lines across the spectrum from the millimeter to the UV were discussed, with most of the focus on the interstellar medium, but also some topics on the circumgalactic medium. The most important quality of a useful model is a good synergy with observations and experiments. Challenges in simulating line emission are identified, some of which are already being worked upon, and others that must be addressed in the future for models to agree with observations. Recent advances in several areas aiming at achieving that synergy are summarized here, from micro-physical to galactic and circum-galactic scale.2 of 29 us to characterize the mass, composition, and chemical state of the ISM, as well as to trace galaxy properties such as star formation rate (SFR), metallicity and dynamics. For example, the emission from major cooling lines, such as Hα or [C II], is sensitive to the physical conditions (densities, radiation field) and dynamics of the ISM. In addition, emission lines work on all physical scales, from galaxy dynamics and inflows to turbulent and collapse motions in star-forming clouds and cores. By systematically comparing spectral-line signatures of different physical models, one can correctly identify the physical processes occurring in these regions. Furthermore, the emission from ionized interstellar gas contains particularly valuable information about the nature of the ionizing radiation sources in a galaxy. In fact, prominent optical emission lines are routinely used to estimate whether ionization is dominated by young massive stars (tracing SFR), an AGN or evolved, post-asymptotic giant branch (post-AGB) stars. Three of the most widely used line-ratio diagnostic "BPT" diagrams 1 , relate the [OIII]/Hβ ratio to the [NII]/Hα, [SII]/Hα and [OI]/Hα ratios. These diagrams have proven useful in identifying the nature of the ionizing radiation in large samples of galaxies in the local Universe [2,3]. Complementary to line emission are the observations of absorption lines of the circumgalactic medium (CGM), which can give key information on the history of the feedback, in terms of chemical, ionization, and thermodynamical state of the outflowing/inflowing gas, that regulates the star formation process. Gas kinematics, from both emission and absorption, give information about large scale gas flows. Thus galactic outflows, from active galactic nuclei (AGN) and starbursts, can be combined with CGM absorption line observations, to study the star formation history, AGN activity history, and feedback processes that regulate both the evolution of the galaxy and its environment.Looking back on the past three decades, t...

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“…[2] Accurate PI cross sections are required for this ion and various ionization stages of Ni to solve the problem of solar opacity. The R-matrix scattering calculations for the electron collisional excitation of Ni XII has recently been reported by Del Zanna et al [5] Nickel is the most abundant transition element existing in different ionization stages in the sun and other astrophysical plasmas after iron. As Ni emission lines have been detected in the spectra of a variety of astronomical objects such as black hole x-ray binaries, [6,7] clusters of galaxies, [8] supernova remnants, [9] and the center of our Galaxy.…”

Section: Introductionmentioning

confidence: 97%

Dirac R-matrix calculations of photoionization cross sections of Ni XII and atomic structure data of Ni XIII

et al. 2017

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We performed R-matrix calculations for photoionization cross sections of the two ground state configuration 3s 2 3p 5 ( 2 P o 3/2,1/2 ) levels and 12 excited states of Ni XII using relativistic Dirac Atomic R-matrix Codes (DARC) across the photon energy range between the ionizations thresholds of the corresponding states and well above the thresholds of the last level of the Ni XIII target ion. Generally, a good agreement is obtained between our results and the earlier theoretical photoionization cross sections. Moreover, we have used two independent fully relativistic GRASP and FAC codes to calculate fine-structure energy levels, wavelengths, oscillator strengths, transitions rates among the lowest 48 levels belonging to the configuration (3s 2 3p 4 , 3s3p 5 , 3p 6 , 3s 2 3p 3 3d) in Ni XIII. Additionally, radiative lifetimes of all the excited states of Ni XIII are presented. Our results of the atomic structure of Ni XIII show good agreement with other theoretical and experimental results available in the literature. A good agreement is found between our calculated lifetimes and the experimental ones. Our present results are useful for plasma diagnostic of fusion and astrophysical plasmas.

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Atomic data for astrophysics: Ni XII

Cited by 11 publications

References 45 publications

Solar UV and X-ray spectral diagnostics

Solar UV and X-ray spectral diagnostics

Challenges and Techniques for Simulating Line Emission

Dirac R-matrix calculations of photoionization cross sections of Ni XII and atomic structure data of Ni XIII

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