Circumstellar Material around Main Sequence and Evolved Stars

Abstract

Our current understanding of dust and gas orbiting around main sequence stars as evidenced by IR photometry, optical coronography and high resolution UV spectroscopy is reviewed and placed in the context of protoplanetary system formation and evolution. The case of Beta Pictoris, the brightest known Vega-like disk, is used as an example of the kind of information one might be able to deduce from the highest possible spatial resolution and contrast measurements planned in the near future from the ground and space. The possible existence of planetary-sized bodies in the Beta Pic disk, its evolutionary stage and the incidence of disks around other main sequence stars are also topics of great interest in this field that we can just begin now to clarify with existing and, especially, planned high resolution techniques discussed at this school. Finally, the exciting potential for actually reading the past complex evolutionary history of a star as it winds its way across the HR diagram as impressed on the circumstellar gas and dust structures is explored in some detail. It is shown that much can already be learned from such studies, for example, on supernovae, Miras and luminous blue variables but that only attainment of high contrast milliarcsecond resolution from the optical to the thermal IR will allow a real breakthrough in the quantity and quality of data required for this important endeavour