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Astron. Astrophys. Suppl. Ser.
Volume 129, Number 1, April I 1998
Page(s) 161 - 172
Published online 15 April 1998
DOI: 10.1051/aas:1998394

A&A Supplement series, Vol. 129, April I 1998, 161-172

Received July 17; accepted September 12, 1997

Atomic data from the IRON Project

XXVIII. Electron excitation of the tex2html_wrap_inline503 fine structure transition in fluorine-like ions at higher temperatures

K.A. Berringtontex2html_wrap549, H.E. Saraphtex2html_wrap551, and J.A. Tullytex2html_wrap553

tex2html_wrap555  Department of Applied Mathematics & Theoretical Physics, The Queen's University of Belfast, Belfast BT7 1NN, UK
tex2html_wrap557  Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, UK
tex2html_wrap559  Département Giovanni Domenico Cassini, Observatoire de la Côte d'Azur, BP. 4229, 06304 Nice Cedex 4, France


The collision strength tex2html_wrap_inline505 for the fine structure transition within the ground term of 17 fluorine-like ions from Mg IV to Ni XX is calculated using the R-matrix method. We include target terms with n = 3 in order to take account of the resonance structure in tex2html_wrap_inline511 at energies above tex2html_wrap_inline513. These resonances are delineated using a fine mesh of several thousand energy points to scan the region between the first and 27th excited terms. Results from an earlier calculation (IRON Project Paper IV) are used to cover the region below tex2html_wrap_inline515. We make use of the fact that tex2html_wrap_inline511 tends to the Born limit as the collision energy tex2html_wrap_inline519. The effective collision strength tex2html_wrap_inline521 is tabulated as a function of logtex2html_wrap_inline523, where tex2html_wrap_inline525 is a Z-scaled temperature. We compare results for Si+5, Fe+17 and Ni+19 with those obtained by Mohan and co-workers. An explanation is given for the large discrepancy in the case of tex2html_wrap_inline535.

keywords: atomic data -- atomic processes

Copyright by the European Southern Observatory (ESO)

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