INCORPORATION OF DENSITY-FLUCTUATIONS INTO PHOTOIONIZATION CALCULATIONS

A method is proposed whereby a distribution of density inhomogeneities can be incorporated into photoionization calculations. A continuous spectrum of densities is assumed for the gas by defining a density-dependent volume filling factor is-an-element-of N is-proportional-to N(-gamma). The ionization in the condensations is affected by shadowing, and can be computed in terms of the density by dividing the condensations into distinct ionization zones of hydrogen and helium, and assuming each to have a constant continuum optical depth throughout the zone. Emission line fluxes are computed by transforming the standard emissivity volume integral into an integral over density, utilizing the filling factor. Applied to novae, it is shown that the density above which condensations become neutral remains constant in time during the early expansion, and that a considerable fraction of the ejecta is shadowed from the central ionizing source.