Astron. Astrophys. Suppl. Ser. 135, 359-370

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

R.E.S. Clegg ¹ - S. Miller ² - P.J. Storey ² - R. Kisielius ²

Send offprint request: P.J. Storey

1 - Particle Physics and Astronomy Research Council, Polaris House, North Star Avenue, Swindon, Wiltshire SN2 1SZ, UK
2 - Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK

Received July 1, 1993; accepted October 21, 1998

Abstract:

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

Key words: atomic data -- line: formation -- line: profiles -- H II regions -- planetary nebulae: general