Dielectronic recombination data for dynamic finite-density plasmas

Altun, Zikri; Yumak, A.; Yavuz, İlhan; Badnell, N. R.; Loch, S. D.; Pindzola, M. S.

doi:10.1051/0004-6361:20078238

Cited by 64 publications

(48 citation statements)

References 50 publications

(120 reference statements)

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“…RR dominates DR only at low temperatures (less than 1000-5000 K) for Se + , Se 3+ , and Se 6+ . This highlights the importance of obtaining accurate DR rate coefficients, as it is the principal recombination process for low-charge Se ions (and indeed for many other heavy elements, as noted for example by Badnell 2006a; Altun et al 2007;Nikolić et al 2010) in photoionized nebulae.…”

Section: Dielectronic Recombination Rate Coefficientsmentioning

confidence: 89%

Atomic data for neutron-capture elements

Sterling

Witthoeft

2011

A&A

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We present multi-configuration Breit-Pauli AUTOSTRUCTURE calculations of distorted-wave photoionization (PI) cross sections, and total and partial final-state resolved radiative recombination (RR) and dielectronic recombination (DR) rate coefficients for the first six ions of the trans-iron element Se. These calculations were motivated by the recent detection of Se emission lines in a large number of planetary nebulae. Se is a potentially useful tracer of neutron-capture nucleosynthesis, but accurate determinations of its abundance in photoionized nebulae have been hindered by the lack of atomic data governing its ionization balance. Our calculations were carried out in intermediate coupling with semi-relativistic radial wavefunctions. PI and recombination data were determined for levels within the ground configuration of each ion, and experimental PI cross-section measurements were used to benchmark our results. For DR, we allowed Δn = 0 core excitations, which are important at photoionized plasma temperatures. We find that DR is the dominant recombination process for each of these Se ions at temperatures representative of photoionized nebulae (∼10 4 K). In order to estimate the uncertainties of these data, we compared results from three different configuration-interaction expansions for each ion, and also tested the sensitivity of the results to the radial scaling factors in the structure calculations. We find that the internal uncertainties are typically 30-50% for the direct PI cross sections and ∼10% for the computed RR rate coefficients, while those for low-temperature DR can be considerably larger (from 15-30% up to two orders of magnitude) due to the unknown energies of near-threshold autoionization resonances. These data are available at the CDS, and fitting coefficients to the total RR and DR rate coefficients are presented. The results are suitable for incorporation into photoionization codes used to numerically simulate astrophysical nebulae, and will enable robust determinations of nebular Se abundances.

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Section: Dielectronic Recombination Rate Coefficientsmentioning

confidence: 89%

Atomic data for neutron-capture elements

Sterling

Witthoeft

2011

A&A

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“…Rate coefficients for ground state dielectronic recombination are taken from Badnell (2006a) for hydrogen-like ions, from Bautista & Badnell (2007) for helium-like ions, from Colgan et al (2004) for lithiumlike ions, from Colgan et al (2003) for the beryllium-like ions, Altun et al (2005) for the boron-like ions, from Zatsarinny et al (2005b) for carbon-like ions, Mitnik & Badnell (2004) for nitrogen-like ions, Zatsarinny et al (2005a) for oxygen-like ions, Zatsarinny et al (2006) for fluorine-like ions, Zatsarinny et al (2004) for neon-like ions, Altun et al (2006) for sodium-like ions, and Altun et al (2007) for magnesium-like ions. This set of calculations provide a coherent set of dielectronic recombination rates and we have adopted them as a standard by which to assess the validity of other calculations.…”

Section: Dielectronic Recombination 321 H Through Mg Isoelectronicmentioning

confidence: 99%

CHIANTI – an atomic database for emission lines

Dere¹,

Landi²,

Young³

et al. 2009

A&A

464

451

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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

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“…These uncertainties are magnified by the fact that DR is the dominant form of recombination for low-charge Kr ions at the temperatures of photoionized astrophysical nebulae, with the rate coefficients exceeding those of RR by as much as two orders of magnitude. The dominance of DR over RR in photoionized nebulae is common for heavy element ions (e.g., Badnell 2006a; Altun et al 2007;Nikolić et al 2010;Sterling & Witthoeft 2011).…”

Section: Discussionmentioning

confidence: 99%

Atomic data for neutron-capture elements

Sterling

Witthoeft

2011

A&A

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We present multi-configuration Breit-Pauli distorted-wave photoionization (PI) cross sections and radiative recombination (RR) and dielectronic recombination (DR) rate coefficients for the first six krypton ions. These were calculated with the AUTOSTRUCTURE code, using semi-relativistic radial wavefunctions in intermediate coupling. Kr has been detected in several planetary nebulae (PNe) and H II regions, and is a useful tracer of neutron-capture nucleosynthesis. PI, RR, and DR data are required to accurately correct for unobserved Kr ions in photoionized nebulae, and hence to determine elemental Kr abundances. PI cross sections have been determined for ground configuration states of Kr 0 −Kr 5+ up to 100 Rydbergs. Our Kr + PI calculations were significantly improved through comparison with experimental measurements. RR and DR rate coefficients were respectively determined from the direct and resonant PI cross sections at temperatures (10 1 −10 7 )z 2 K, where z is the charge. We account for Δn = 0 DR core excitations, and find that DR is the dominant recombination mechanism for all but Kr + at photoionized plasma temperatures. Internal uncertainties are estimated by comparing results computed with three different configuration-interaction expansions for each ion, and by testing the sensitivity to variations in the orbital radial scaling parameters. The PI cross sections are generally uncertain by 30−50% near the ground state thresholds. Near 10 4 K, the RR rate coefficients are typically uncertain by less than 10%, while those of DR exhibit uncertainties of factors of 2 to 3, due to the unknown energies of near-threshold autoionizing resonances. With the charge transfer rate coefficients presented in the third paper of this series, these data enable robust Kr abundance determinations in photoionized nebulae for the first time, providing a new tool for studying heavy element enrichments in PNe and for investigating the chemical evolution of trans-iron elements.

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Dielectronic recombination data for dynamic finite-density plasmas

Cited by 64 publications

References 50 publications

Atomic data for neutron-capture elements

Atomic data for neutron-capture elements

CHIANTI – an atomic database for emission lines

Atomic data for neutron-capture elements

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