Atomic data from the IRON project - LXVI. Electron impact excitation of Fe18+

K. Butler, N.R. Badnell

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Context. Accurate electron collisional data are required for the analysis of the Fe XIX astrophysical spectrum, in particular in the sun. Such an analysis can provide information on the physical characteristics of the coronal plasma. Aims. An extensive target is used in an R-matrix scattering calculation to provide the necessary data for Fe18+. The use of the R-matrix method includes the resonance contribution lacking in the distorted wave approach and the large target improves the accuracy of the close-coupling approximation. Methods. The R-Matrix package described by Berrington et al. (1995, Comput. Phys. Commun., 92, 290) as provided by the UK RmaX project has been used to calculate electron collisional data among 342 levels of Fe18+. We have used the intermediate-coupling frame-transformation (ICFT) method (Griffin et al. 1998, J. Phys. B: At. Mol. Opt. Phys., 31, 3713) to transform data obtained in a 166 term LS-coupling calculation. Contributions from the mass and Darwin interactions have also been included in the Hamiltonian. Results. Collision stengths for all transitions between the 342 levels of Fe18+ are presented. They are tabulated over a wide range of electron temperatures of astrophysical interest. The results are compared with the earlier Iron Project work of Butler & Zeippen (2001, A&A, 372, 1083) and also with that of McLaughlin et al. (2001, J. Phys. B: At. Mol. Opt. Phys., 34, 4521) and Landi & Gu (2006, ApJ, 640, 1171). The agreement is reasonable for the low-lying transitions. Larger differences are found for the more highly excited states.
Original languageEnglish
Pages (from-to)1369-1376
Number of pages7
JournalAstronomy and Astrophysics
Volume489
Issue number3
DOIs
Publication statusPublished - Oct 2008

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electron impact
electron
astrophysics
excitation
matrix
S matrix theory
matrix methods
sun
electrons
electron energy
iron
collisions
transform
collision
scattering
approximation
plasma
project
interactions
method

Keywords

  • atomic data
  • atomic processes
  • plasmas

Cite this

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title = "Atomic data from the IRON project - LXVI. Electron impact excitation of Fe18+",
abstract = "Context. Accurate electron collisional data are required for the analysis of the Fe XIX astrophysical spectrum, in particular in the sun. Such an analysis can provide information on the physical characteristics of the coronal plasma. Aims. An extensive target is used in an R-matrix scattering calculation to provide the necessary data for Fe18+. The use of the R-matrix method includes the resonance contribution lacking in the distorted wave approach and the large target improves the accuracy of the close-coupling approximation. Methods. The R-Matrix package described by Berrington et al. (1995, Comput. Phys. Commun., 92, 290) as provided by the UK RmaX project has been used to calculate electron collisional data among 342 levels of Fe18+. We have used the intermediate-coupling frame-transformation (ICFT) method (Griffin et al. 1998, J. Phys. B: At. Mol. Opt. Phys., 31, 3713) to transform data obtained in a 166 term LS-coupling calculation. Contributions from the mass and Darwin interactions have also been included in the Hamiltonian. Results. Collision stengths for all transitions between the 342 levels of Fe18+ are presented. They are tabulated over a wide range of electron temperatures of astrophysical interest. The results are compared with the earlier Iron Project work of Butler & Zeippen (2001, A&A, 372, 1083) and also with that of McLaughlin et al. (2001, J. Phys. B: At. Mol. Opt. Phys., 34, 4521) and Landi & Gu (2006, ApJ, 640, 1171). The agreement is reasonable for the low-lying transitions. Larger differences are found for the more highly excited states.",
keywords = "atomic data, atomic processes, plasmas",
author = "K. Butler and N.R. Badnell",
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language = "English",
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Atomic data from the IRON project - LXVI. Electron impact excitation of Fe18+. / Butler, K.; Badnell, N.R.

In: Astronomy and Astrophysics, Vol. 489, No. 3, 10.2008, p. 1369-1376.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Atomic data from the IRON project - LXVI. Electron impact excitation of Fe18+

AU - Butler, K.

AU - Badnell, N.R.

PY - 2008/10

Y1 - 2008/10

N2 - Context. Accurate electron collisional data are required for the analysis of the Fe XIX astrophysical spectrum, in particular in the sun. Such an analysis can provide information on the physical characteristics of the coronal plasma. Aims. An extensive target is used in an R-matrix scattering calculation to provide the necessary data for Fe18+. The use of the R-matrix method includes the resonance contribution lacking in the distorted wave approach and the large target improves the accuracy of the close-coupling approximation. Methods. The R-Matrix package described by Berrington et al. (1995, Comput. Phys. Commun., 92, 290) as provided by the UK RmaX project has been used to calculate electron collisional data among 342 levels of Fe18+. We have used the intermediate-coupling frame-transformation (ICFT) method (Griffin et al. 1998, J. Phys. B: At. Mol. Opt. Phys., 31, 3713) to transform data obtained in a 166 term LS-coupling calculation. Contributions from the mass and Darwin interactions have also been included in the Hamiltonian. Results. Collision stengths for all transitions between the 342 levels of Fe18+ are presented. They are tabulated over a wide range of electron temperatures of astrophysical interest. The results are compared with the earlier Iron Project work of Butler & Zeippen (2001, A&A, 372, 1083) and also with that of McLaughlin et al. (2001, J. Phys. B: At. Mol. Opt. Phys., 34, 4521) and Landi & Gu (2006, ApJ, 640, 1171). The agreement is reasonable for the low-lying transitions. Larger differences are found for the more highly excited states.

AB - Context. Accurate electron collisional data are required for the analysis of the Fe XIX astrophysical spectrum, in particular in the sun. Such an analysis can provide information on the physical characteristics of the coronal plasma. Aims. An extensive target is used in an R-matrix scattering calculation to provide the necessary data for Fe18+. The use of the R-matrix method includes the resonance contribution lacking in the distorted wave approach and the large target improves the accuracy of the close-coupling approximation. Methods. The R-Matrix package described by Berrington et al. (1995, Comput. Phys. Commun., 92, 290) as provided by the UK RmaX project has been used to calculate electron collisional data among 342 levels of Fe18+. We have used the intermediate-coupling frame-transformation (ICFT) method (Griffin et al. 1998, J. Phys. B: At. Mol. Opt. Phys., 31, 3713) to transform data obtained in a 166 term LS-coupling calculation. Contributions from the mass and Darwin interactions have also been included in the Hamiltonian. Results. Collision stengths for all transitions between the 342 levels of Fe18+ are presented. They are tabulated over a wide range of electron temperatures of astrophysical interest. The results are compared with the earlier Iron Project work of Butler & Zeippen (2001, A&A, 372, 1083) and also with that of McLaughlin et al. (2001, J. Phys. B: At. Mol. Opt. Phys., 34, 4521) and Landi & Gu (2006, ApJ, 640, 1171). The agreement is reasonable for the low-lying transitions. Larger differences are found for the more highly excited states.

KW - atomic data

KW - atomic processes

KW - plasmas

UR - http://dx.doi.org/10.1051/0004-6361:200810197

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DO - 10.1051/0004-6361:200810197

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SP - 1369

EP - 1376

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

IS - 3

ER -