Astron. Astrophys. Suppl. Ser. 143, 483-489

Atomic data from the IRON Project

XLII. Electron impact excitation of Fe  XXI

K. Butler ¹ - C.J. Zeippen²

Send offprint request: K. Butler

1 - Institut für Astronomie und Astrophysik, Scheinerstr. 1, D-81679 München, Germany
2 - UMR 8631 (associée au CNRS et à l'Université Paris 7) et DAEC, Observatoire de Paris, F-92195 Meudon, France

Received January 20; accepted February 8, 2000

Abstract:

Collision strengths and collisional rate parameters are provided for transitions among the n=2 and 2p$3\ell$ levels of C-like Fe XXI. The data have been computed in a 52-state Breit-Pauli approximation thus accounting for the most prominent relativistic effects. An R-matrix close-coupling calculation comprising partial wave contributions up to J=59/2 and of order 8000 energy points in the range up to 260 Ryd gave cross sections expected to be accurate to better than 20% for transitions among the n=2 levels.

Key words: atomic data -- atomic processes