Theoretical models of planetary nebulae

Theoretical models are attempted for eight moderate excitation planetary nebulae which have been intensively observed with the image-tube scanner at Lick and in other investigations. The models are uniform density structures, often truncated, with central star energy distributions and chemical compositions so adjusted as to give an optimum fit with the observations. Although a satisfactory representation can be obtained for most of the stronger, usually observed lines, those arising from the 3p³ configuration, specifically the nebular transitions of [Sii], [Cliii], and [Ariv], often give difficulties. A comparison with results of model predictions with those from simple, traditional procedures generally shows a good agreement, except in those instances where different judgments are made in interpreting emissions of ions of 3pⁿ configurations.