TRACE OF PLANETARY-NEBULA EVOLUTION BY DISTANCE-INDEPENDENT PARAMETERS

Using existing infrared and radio data on a sample of 432 planetary ne bulae, we have derived a number of distance-independent parameters for comparison with evolutionary models of planetary nebulae. We find tha t many of the observed properties of planetary nebulae can be explaine d by current central star evolutionary models, even if the time scales are subject to significant change by a factor of up to an order of ma gnitude. Specifically, we find that the evolutionary tracks are well s eparated in the radio surface brightness-central star temperature plan e, therefore allowing us to determine the core mass of individual plan etary nebulae. We also obtain the luminosity and gravity of the centra l stars of individual nebulae, from their temperature and core mass, w ithout relying on the distance assumptions. We find our results of the core mass are in good agreement with those of Mendez, Kudritzki, & He rrero and Tylenda et al. A systematic, large discrepancy is found betw een the luminosity found in this work and that found by Gathier & Pott asch.