IONIC PROCESSES IN ASTROPHYSICS

Ions are ubiquitous in astrophysical environments. Knowledge of the cr oss sections and rates for the atomic and molecular processes which cr eate ions and which destroy them is an important part of any detailed model of an astronomical object. Ions and ionic collisions in two very different environments, the early Universe and planetary nebulae, are explored in this paper. Electron-ion recombination leading to the eve ntual formation of primordial molecules is described. Collisions of io ns with electrons and atoms, central to the interpretation of emission lines in astrophysical plasmas, are discussed. Recent work in predict ing element abundances in planetary nebulae is highlighted.