Astron. Astrophys. Suppl. Ser. 136, 385-394

Atomic data from the IRON Project

XXXIV. Electron impact excitation of Fe XVI

W. Eissner¹ - M.E. Galavís^2,4 - C. Mendoza^3,4 - C.J. Zeippen⁴

Send offprint request: C.J. Zeippen

1 - Lehrstuhl für Theoretische Physik I, Ruhr-Universität, D-44780 Bochum, Germany
2 - Departamento de Física, Universidad Metropolitana, PO Box 76819, Caracas 1070A, Venezuela
3 - Centro de Física, Instituto Venezolano de Investigaciones Científicas (IVIC), PO Box 21827, Caracas 1020A, Venezuela
4 - UMR 8631 (associée au CNRS et à l'Université Paris 7) et DAEC, Observatoire de Paris, F-92195 Meudon, France

Received September 25; accepted November 18, 1998

Abstract:

As part of the IRON Project, electron impact excitation effective collision strengths are computed for the ion Fe XVI familiar in solar spectra. A Breit-Pauli R-matrix calculation is performed with a 12-level ($n\leq 4$)target representation. The calculation for this relatively simple ion is approached as a test case where we can analyze in detail most of the effects that contribute to the accuracy of the collision strengths: the energy mesh, relativistic corrections, the asymptotic multipole potentials and contributions from high partial waves. By comparing with two recent independent calculations, an accuracy rating of 10% is assigned to the present effective collision strengths in the electron-temperature range of $10^5\leq T/{K}\leq 10^7$.

Key words: atomic and molecular data -- sun: corona