High Excitation ISM and Gas

An overview is given of ISO results on regions of high excitation ISM and gas, i.e. HII regions, the Galactic Centre and Supernova Remnants. IR emission due to fine-structure lines, molecular hydrogen, silicates, polycyclic aromatic hydrocarbons and dust are summarised, their diagnostic capabilities illustrated and their implications highlighted. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, The Netherlands, and the United Kingdom), and with the participation of ISAS and NASA.     

A model for the chemical evolution of the solar neighborhood using metallicity dependent yields

We discuss the results from a chemical evolution model of the local galactic disk which takes into account stellar yields, lifetimes, remnants, and supernova progenitor masses which depend on the initial metallicity of the collapsing clouds. The detailed evolution of H, He, C, O, Fe, and of the heavy elements (Z) is followed dropping the instantaneous recycling approximation. Our results reproduce the majority of the observational constraints.