The evolution of planetary nebulae.
VII. Modelling planetary nebulae of distant stellar systems

Planetary nebulae are increasingly becoming important tracers of elemental abundances and abundance gradients in external galaxies. Abundance determinations in these objects, however, depend both on the dynamical evolution of the nebula and on the evolution of its central star. In the article highlighted in this issue, Schönberner et al. study these effects as a function of metallicity and find both that the metal content affects the dynamical evolution of the nebula and that photoheating and line cooling are not always in balance, as usually assumed.