Determination of the helium abundances in galactic planetary nebulae
Abstract:We present the results of detailed studies on the He ionic abundances in galactic planetary nebulae. They are based on the newest emissivity data obtained by Benjamin et al. and take into account both the radiative transfer effects in the He I emission lines and the impact excitation of He and H atoms. The new values of the He +-to-H + and He-to-H ratios are obtained for different cases of He I line conjunctions.
Document Type: Research Article
Publication date: December 1, 2003