MID-IR IMAGING AND MODELING OF AGB CIRCUMSTELLAR ENVELOPES

We present new mid-IR images of AGE and post-AGE circumstellar envelop es (CSEs) obtained with the 10-20 mu m imaging camera CAMIRAS mounted at the TIRGO infrared telescope (Gornergrat, Switzerland). Diffraction limited images of the sources ate obtained, and extended emission for the brightest sources is detected for several arcseconds. Simple radi ative transfer modelling is necessary to fit the observed data and der ive the physical and chemical state of the envelope. This kind of anal ysis is an important test for dust formation theories, because it give s indications of dust properties along their condensation path through the envelope.