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Journal ArticleDOI

Ionization Equilibria for High Ions of Fe and Ni

01 May 1970-Monthly Notices of the Royal Astronomical Society (Oxford University Press)-Vol. 148, Iss: 1, pp 17-23
About: This article is published in Monthly Notices of the Royal Astronomical Society.The article was published on 1970-05-01 and is currently open access. It has received 85 citations till now. The article focuses on the topics: Ionization & Ion.
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Journal ArticleDOI
TL;DR: For 47 elements in the range 2 ≤ Z ≤ 92, steady-state radiative cooling rates, average charge states, and mean square charge states have been calculated for low-density, high-temperature plasmas (n e ≲ 10 16 electrons/cm 3 and T = 0.002-100 keV) as discussed by the authors.

743 citations

Journal ArticleDOI
TL;DR: The CHIANTI database as mentioned in this paper provides a set of atomic data for the interpretation of astrophysical spectra emitted by collisionally dominated, high temperature, optically thin sources.
Abstract: Aims. The goal of the CHIANTI atomic database is to provide a set of atomic data for the interpretation of astrophysical spectra emitted by collisionally dominated, high temperature, optically thin sources. Methods. A complete set of ground level ionization and recombination rate coefficients has been assembled for all atoms and ions of the elements of H through Zn and inserted into the latest version of the CHIANTI database, CHIANTI 6. Ionization rate coefficients are taken from the recent work of Dere (2007, A&A, 466, 771) and recombination rates from a variety of sources in the literature. These new rate coefficients have allowed the calculation of a new set of ionization equilibria and radiative loss rate coefficients. For some ions, such as Fe viii and Fe ix, there are significant differences from previous calculations. In addition, existing atomic parameters have been revised and new atomic parameters inserted into the database. Results. For each ion in the CHIANTI database, elemental abundances, ionization potentials, atomic energy levels, radiative rates, electron and proton collisional rate coefficients, ionization and recombination rate coefficients, and collisional ionization equilibrium populations are provided. In addition, parameters for the calculation of the continuum due to bremsstrahlung, radiative recombination and two-photon decay are provided. A suite of programs written in the Interactive Data Language (IDL) are available to calculate line and continuum emissivities and other properties. All data and programs are freely available at http://wwwsolar.nrl.navy.mil/ chianti

513 citations


Cites background from "Ionization Equilibria for High Ions..."

  • ...These include those by Jordan (1969, 1970), Summers (1974), Jacobs et al. (1979, 1977a,b, 1980); Jacobs (1985), Shull & Van Steenberg (1982), Arnaud & Rothenflug (1985), Landini & Monsignori Fossi (1991), Arnaud & Raymond (1992), Mazzotta et al. (1998), Mazzitelli & Mattioli (2002), Bryans et al.…...

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Journal ArticleDOI
TL;DR: In this paper, the authors calculate dielectronic recombination rate coefficients for the Be-like and B-like ions Fe22+ and Fe21+ using a multiconfiguration LS-coupling expansion and allowing for Delta nc=0 and Delta Nc=1 autoionising transition into the continuum of excited states.
Abstract: The author calculates dielectronic recombination rate coefficients for the Be-like and B-like ions Fe22+ and Fe21+ using a multiconfiguration LS-coupling expansion and allowing for Delta nc=0 and Delta nc=1 autoionising transition into the continuum of excited states. The effect of intermediate coupling is also investigated and found to be less than 10%. They use autostructure-a general program for the calculation of multiconfiguration LS-coupling or intermediate-coupling autoionisation transition rates (incorporating superstructure)-to calculate the dielectronic recombination rate coefficient for the 1-2 and 2-3 core transitions. Together with the Burgess general formula for the 2-2 transition, they obtain about 95% of the total dielectronic recombination rate coefficient for ground state and look at its effect on the ionisation balance for a steady-state plasma. They confirm the recent findings of Smith et al. (1985) that the effect of Delta nc=0 secondary autoionisation is much less significant for highly charged ions than was suggested by Jacobs et al.

287 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigate the conversion of the 0.5-4 and 1-8 A soft X-ray flux measurements made by detectors on the Geostationary Operational Environmental Satellites (GOES) into temperature and emission measures of coronal plasma using modern spectral models and modern understanding of the coronal abundances.
Abstract: {We investigate the conversion of the 0.5–4 and 1–8 A soft X-ray flux measurements made by detectors on the Geostationary Operational Environmental Satellites (GOES) into temperature and emission measures of coronal plasma using modern spectral models and modern understanding of coronal abundances. In particular, the original analysis by Thomas, Starr and Crannell (1985) is updated to take into account the realization that coronal abundances may be quite different from photospheric abundances. An important result of this analysis is that the derived temperatures and emission measures depend strongly on the assumed abundances even at high temperatures where continuum rather than spectral lines dominates the Sun’s X-ray spectrum. This occurs because the higher coronal abundances mean that most of the continuum is due to free–bound emission processes, not free–free emission, and thus is abundance-dependent. We find significant differences between modern calculations of the temperature response of the flux measurements and the versions currently in use: for a typical flare, emission measures may be up to a factor of 4 smaller than the current software suggests. Derived temperatures are similar for both photospheric and coronal abundances for cool flares (e.g., 15 MK), but for hot flares (e.g., 35 MK) coronal abundances can lead to significantly (~25%) lower temperatures being derived.

195 citations


Cites methods from "Ionization Equilibria for High Ions..."

  • ...For their temperature–dependence calculations, Thomas et al. (1985) used spectra provided by McKenzie based on calculations by Walker (see Walker, Jr. et al., 1974) with other supporting material, and used ionization–balance calculations by Jordan (1970)....

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Journal ArticleDOI
TL;DR: In this article, a review of the analysis and interpretation of the satellite lines in terms of the physical parameters characterising the emitting plasma is presented, and extensive results concerning the astrophysically important hydrogen-like and helium-like ions are summarised.
Abstract: Dielectronic recombination is a process particularly effective in high-temperature dilute plasmas such as those observed, for example, in astrophysics. This process was first recognised for its noticeable effects on the establishment of ionisation equilibrium in the solar corona. Over the last decade, its importance as a line formation mechanism has been emphasised. It is responsible for spectral lines appearing as satellites to the long-wavelength side of the resonance lines of the highly ionised systems typical of hot plasmas. However, in transient ionising plasmas and for the heavier ions these lines can also be produced by direct excitation of an inner-shell electron. This review is concerned essentially with the analysis and interpretation of the satellite lines in terms of the physical parameters characterising the emitting plasma. Extensive results concerning the astrophysically important hydrogen-like and helium-like ions are summarised. These are compared with the few available high-resolution soft X-ray spectra of solar active regions and flares.

193 citations