Forbidden transitions in Li-like ions: Compact effective collision strengths for where

A. Burgess; M. C. Chidichimo; J. A. Tully

doi:10.1051/aas:1998258

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Volume 131 / No 1 (July 1998)

Astron. Astrophys. Suppl. Ser., 131 1 (1998) 145-152

Abstract

Free Access

Issue		Astron. Astrophys. Suppl. Ser. Volume 131, Number 1, July 1998


Page(s)		145 - 152
DOI		https://doi.org/10.1051/aas:1998258
Published online		15 July 1998

Astron. Astrophys. Suppl. Ser. 131, 145-152 (1998)

Forbidden transitions in Li-like ions: Compact effective collision strengths for ${\rm 2s} - n{\rm s},n{\rm d}$ where $n = 3,\, 4,\, 5$ ^*

A. Burgess¹, M. C. Chidichimo² and J. A. Tully³

¹ Department of Applied Mathematics and Theoretical Physics, Silver Street, Cambridge CB3 9EW, UK
² Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
³ Département G.D. Cassini, Observatoire de la Côte d'Azur, BP. 4229, 06304 Nice Cedex 4, France e-mail: tully@obs-nice.fr

Received: 25 September 1995
Accepted: 2 January 1998

Abstract

Using an extension of the method for compacting atomic data set out by Burgess & Tully (1992), we make concise fits to a selection of the set of collision strengths ${\sl \Omega}$ given by Zhang et al. (1990) for Li-like ions from O⁺⁵ to U⁺⁸⁹. We carry out thermal averaging and fit the resulting effective collision strengths ${\sl \Upsilon}$ . A compact $5\times5$ or $4\times4$ table of cardinal values for each transition allows one to reproduce the T and Z dependent ${\sl \Upsilon}$ to better than 1 per cent. The present study is for the forbidden transitions $\rm 2s \to 3s,4s,5s$ and $\rm 2s \to 3d,4d,5d$ .

Key words: Li-like ions / electron excitation / compact atomic data

^*

Appendix available on the on-line version of A&AS.

Forbidden transitions in Li-like ions: Compact effective collision strengths for where *

Forbidden transitions in Li-like ions: Compact effective collision strengths for ${\rm 2s} - n{\rm s},n{\rm d}$ where $n = 3,\, 4,\, 5$ ^*