Diffuse ionizing radiation in nebular envelopes of symbiotic novae V1016 Cyg and HM Sge

The ionizing structure of the nebular envelopes of the symbiotic novae V1016 Cyg and HM Sge were determined using Ferland's photoionization code Cloudy upgraded by our method DiffRaY for a detailed calculation of the diffuse ionzing radiation. Our calculations are based on the optimal photoionization models, obtained previously for these objects using the standard code Cloudy that takes into account the diffuse ionizing radiation using an outward only approximation. In the present paper we compare the results of the photoionization modelling of V1016 Cyg and HM Sge nebular envelopes performed using both detailed and outward only methods. It was shown that the approximate fast outward only method can be used for the modelling of these objects.