The kinematic evolution of the ionized shells of planetary nebulae

Abstract

In this contribution we present the results of measuring the bulk outflow, or global expansion velocities for a large number of planetary nebulae (PNe) that span a wide range of evolutionary stages and different stellar populations. The sample comprises 133 PNe from the galactic bulge, 100 mature and highly evolved PNe from the disk, 11 PNe from the galactic halo and 15 PNe with very low central star masses and low metallicities, for a total of 259 PNe. The long-slit, echelle data are drawn from the SPM Kinematic Catalogue of Galactic Planetary Nebulae. These results reveal from a statistical perspective the kinematic evolution of the expansion velocities of PNe in relation with the changing characteristics of the central star's wind and ionizing luminosity and as a function of the evolutionary rate determined by the central star (CS) mass. The large number of PNe utilized in this work for each group of PNe under study and the homogeneity of the data provide for the first time a solid benchmark from observations for models predictions. This project is still in progress and aims at measuring expansion velocities for about 300 more galactic PNe with the aim of providing a reliable parametric description of their expansion velocity in terms of different populations, morphologies, evolutionary stages and CS masses.