Recombination line intensities for hydrogenic ions: The fine-structure components of H I and He II

Emissivities have been calculated for finestructure components of selected UV and optical recombination lines of HI and He II. Results are given for a range of electron temperatures and densities, and in Cases A and B of Bake r & Menzel (1938). Relative intensities, wavelengths and velocity shifts of the fine-structure components are tabulated. Applications to the spectra o f gaseous nebulae are discussed. Depending on the temperature, density and Case, the centres of unresolved lines can shift by up to 0.9 km s(-1) for H I and 3.3 km s(-1) for He II. A new calibration of the H alpha-[N II] meth od for determining electron temperatures is given.