PLANETARY-NEBULAE - A MODERN VIEW

Our current understanding of the origin and evolution of planetary nebulae is reviewed. We now recognize that a planetary nebula represents a dynamical system in which evolution is tightly coupled to the evolution of the central star. Not only is the ionization structure of the nebula controlled by the radiative output from the central star, the dynamics and morphology of the nebula are heavily influenced by the mechanical energy output from the central star. Since the time scale of evolution of the central star is strongly dependent on its mass, the extent of the radiative and mechanical interactions between the star and the nebula not only vary with time, but also vary with stellar mass. The physical properties of planetary nebulae are discussed in this context.