Recombination coefficients for the 5g - 4f transitions of O at nebular temperatures and densities^*

Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK

Send offprint request to: P.J. Storey

Received: 1 February 1999
Accepted: 22 February 1999

Abstract

We calculate effective recombination coefficients for the formation of the 5g - 4f lines of O_III in the intermediate coupling scheme. Photoionization data for the 5g levels calculated using the R-matrix method are used to derive their recombination coefficients. Cascading from higher states is included, allowing for the effects of finite electron density in a hydrogenic approximation. We explicitly include the distribution of population between the two ground levels of O³⁺ in the calculation of the line intensities. The results are presented as a simple programmeable formula allowing the calculation of recombination line intensities for electron temperatures, T_e in the range  K and electron densities, N_e in the range  cm^-3.