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Ar XIII is found to be unique with new features in electron-ion recombination not seen in any other ion. The ion has been studied with the unified method which provides a theoretically self-consistent set of atomic parameters for the…

Astrophysics · Physics 2009-11-10 Sultana N. Nahar

We present coefficients for the calculation of the continuous emission spectra of HI, HeI and HeII due to electron-ion recombination. Coefficients are given for photon energies from the first ionization threshold for each ion to the n=20…

Astrophysics · Physics 2009-11-11 Barbara Ercolano , P. J. Storey

In this paper, the ionization and recombination coefficients of dense semiclassical hydrogen plasma on the basis of the effective interaction potential have been investigated. For this goal the Bohr$-$Lindhard method and method phase…

We have measured the resonance strengths and energies for dielectronic recombination (DR) of Fe XX forming Fe XIX via N=2 --> N'=2 (Delta_N=0) core excitations. We have also calculated the DR resonance strengths and energies using…

A vexing puzzle in the study of planetary nebulae and \ion{H}{2} regions is that the plasma diagnostic results based on collisionally excited lines systematically differ from those based on recombination lines. A fairly speculative…

Solar and Stellar Astrophysics · Physics 2020-08-19 Bao-Zhi Lin , Yong Zhang

Recent spectroscopic models of active galactic nuclei (AGN) have indicated that the recommended electron-ion recombination rate coefficients for iron ions with partially filled M-shells are incorrect in the temperature range where these…

A unified scheme using the R-matrix method has been developed for electron-ion recombination subsuming heretofore separate treatments of radiative and dielectronic recombination (RR and DR). The ab initio coupled channel approach unifies…

Astrophysics · Physics 2009-11-10 Sultana N. Nahar , Anil K. Pradhan

We investigate the effect of resonances in photoionization and recombination cross sections computed using the R-matrix method. Photoionization and recombination rates derived from high-resolution cross sections for oxygen ions are compared…

Astrophysics · Physics 2009-11-10 Franck Delahaye , Sultana N. Nahar , Anil K Pradhan , Hong Lin Zhang

We present a theoretical investigation of dielectronic recombination (DR) of Ar-like ions that sheds new light on the behavior of the rate coefficient at low-temperatures where these ions form in photoionized plasmas. We provide results for…

Atomic Physics · Physics 2013-03-13 D. Nikolić , T. W. Gorczyca , K. T. Korista , N. R. Badnell

We report measured rate coefficients for electron-ion recombination for Si10+ forming Si9+ and for Si9+ forming Si8+, respectively. The measurements were performed using the electron-ion merged-beams technique at a heavy-ion storage ring.…

We have introduced a new method of estimating the electron temperature and density of H II regions by using single dish observations. In this method, multiple hydrogen radio recombination lines of different bands are computed under the…

Solar and Stellar Astrophysics · Physics 2019-11-14 F. -Y. Zhu , Q. -F. Zhu , J. -Z. Wang , J. -S Zhang

We have developed a general model for determining density-dependent effective dielectronic recombination (DR) rate coefficients in order to explore finite-density effects on the ionization balance of plasmas. Our model consists of…

Atomic Physics · Physics 2015-06-15 D. Nikolić , T. W. Gorczyca , K. T. Korista , G. J. Ferland , N. R. Badnell

For photoionized plasmas, electron energy-loss rates due to radiative recombination (RR) are required for thermal equilib- rium calculations, which assume a local balance between the energy gain and loss. While many calculations of total…

High Energy Astrophysical Phenomena · Physics 2017-02-22 Junjie Mao , Jelle Kaastra , N. R. Badnell

We present a comparison of electron densities derived from optical forbidden line diagnostic ratios for a sample of over a hundred nebulae. We consider four density indicators, the [O II] $\lambda3729/\lambda3726$, [S II]…

Astrophysics · Physics 2009-11-10 W. Wang , X. -W. Liu , Y. Zhang , M. J. Barlow

The ion populations most frequently adopted for diagnostics in collisional plasmas are derived from the density independent, coronal approximation. In higher density, lower temperature conditions, ionisation rates are enhanced once…

Solar and Stellar Astrophysics · Physics 2020-07-22 R. P. Dufresne , G. Del Zanna , N. R. Badnell

This review summarizes the present status of an ongoing experimental effort to provide reliable rate coefficients for dielectronic recombination of highly charged iron ions for the modeling of astrophysical and other plasmas. The…

Atomic and Molecular Clusters · Physics 2024-09-30 S. Schippers , M. Lestinsky , A. Müller , D. W. Savin , E. W. Schmidt , A. Wolf

A recently generated theoretical line list of C II dielectronic recombination lines together with observational data gathered from the literature is used to investigate the electron temperature in a range of astronomical objects, mainly…

Solar and Stellar Astrophysics · Physics 2013-01-16 Peter J. Storey , Taha Sochi

Relativistic close coupling calculations are reported for unified electronic recombination of (e + C IV) including non-resonant and resonant recombination processes, radiative and dielectronic recombination (RR and DR). Detailed comparison…

Astrophysics · Physics 2008-11-26 Anil K. Pradhan , Guo Xin Chen , Sultana N. Nahar , Hong Lin Zhang

A hot central star illuminating the surrounding ionized H II region usually produces very rich atomic spectra resulting from basic atomic processes: photoionization, electron-ion recombination, bound-bound radiative transitions, and…

Astrophysics · Physics 2007-05-23 Sultana N. Nahar

We have carried-out multi-configuration Breit-Pauli AUTOSTRUCTURE calculations for the dielectronic recombination (DR) of Fe^{8+} - Fe^{12+} ions. We obtain total DR rate coefficients for the initial ground-level which are an order of…

Astrophysics · Physics 2010-11-11 N. R. Badnell