THE RICH SPECTRUM OF CIRCUMSTELLAR PAHS

We present observations taken with the Short Wavelength Spectrometer ( SWS) on board the Infrared Space Observatory (ISO) of three evolved C- rich stars, the post-AGE star HR 4049 and two planetary nebulae, IRAS2 1282+5050 and NGC 7027. The spectra are dominated by the well-known in frared emission bands, attributed to Polycyclic Aromatic Hydrocarbons (PAHs). The SWS spectra for the first time allow a complete overview o f the richness of the PAH spectrum with high spectral resolution and h igh S/N. We present an inventory of the spectral features in the 2.4-1 7 mu m wavelength window.