Atomic data from the IRON Project: LVIII. Electron impact excitation of Fe XII

A new calculation of rate coefficients for electron collisional excitation of Fe XII is presented and compared to earlier calculations. Significant differences are found with all earlier work due to the inclusion of resonance processes that have not previously been considered and to the use of the i...

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Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 2005-04, Vol.433 (2), p.717-730
Main Authors: STOREY, P. J, DEL ZANNA, G, MASON, H. E, ZEIPPEN, C. J
Format: Article
Language:English
Subjects:
Astrophysics
Physics
Online Access:Get full text
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Summary:A new calculation of rate coefficients for electron collisional excitation of Fe XII is presented and compared to earlier calculations. Significant differences are found with all earlier work due to the inclusion of resonance processes that have not previously been considered and to the use of the intermediate coupling frame transformation method. The resulting dataset of collision strengths is shown to resolve many of the outstanding discrepancies between theory and solar observations. In particular, density sensitive line ratios in Fe XII now indicate electron densities close to those derived from other ions of comparable ionization potential.
ISSN:0004-6361
1432-0746
1432-0756
DOI:10.1051/0004-6361:20041771