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

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, Te in the range 5000 - 20 000 K and electron densities, Ne in the range 102 - 106 cm-3.