Ionization-correction factors for the chemical composition determination of planetary nebulae with density gas fluctuations taking into account

Abstract

270 photo ionization models of planetary nebulae luminescence was calculated. Free parameters for the models grid were energy distribution at the wavelengths 6912˚A, filling factor and chemical composition. T∗ and r∗ in models were selected from Blocker’s evolutional tracks. Energy distributions in nuclei radiation spectra at the wavelengths 6912˚A were taken from Clegg-Middlemass stellar atmosphere models, revised on the stellar wind presence. The nebular shell was assumed to be spherically-symmetrical. The radial distribution of nebular gas density was given by the empirical expression, which was derived by approximating surface brightness distribution for the real planetary nebulae. Density fluctuations were randomly imposed on this distribution. For the grid modeling we used the Cloudy 94 Ferland’s code. Obtained integrated spectra were analyzed, using common nebular gas diagnostic method. Relative abundances of different ions, calculated by this method, were used for determination of analytical expressions for ICFs. Under this spectra analysis the emission lines, for which the influence of density fluctuations may be neglected, were taken into account. As a result, new ICFs were found, and we would going to use these ICFs for obtaining chemical abundances of galactic planetary nebulae more exactly.