Late stages of Stellar Evolution

Abstract. A large fraction of ISO observing time was used to study the late stages of stellar evolution. Many molecular and solid state features, including crystalline silicates and the rota-tional lines of water vapour, were detected for the first time in the spectra of (post-)AGB stars. Their analysis has greatly improved our knowledge of stellar atmospheres and circumstel-lar environments. A surprising number of objects, particularly young planetary nebulae with Wolf-Rayet central stars, were found to exhibit emission features in their ISO spectra that are characteristic of both oxygen-rich and carbon-rich dust species, while far-IR observations of the PDR around NGC 7027 led to the first detections of the rotational line spectra of CH and CH+