A VISIR Mid-infrared Imaging Survey of Post-AGB Stars

cumstellar material in either a dusty torus or a disc. Our team has discovered some discs/tori in the heart of PNe (Lagadec et al., 2006; Chesneau et al., 2006; Matsuura et al., 2006; Chesneau et al., 2007) using adaptive optics on ESO’s Very Large Telescope (VLT) and midinfrared (MIR) interferometry at the Very Large Telescope Interferometer (VLTI). But the role of these discs/tori in the shaping of the nebulae is still unclear, as we know neither the fraction of the total dust mass that is present in these central cores, nor the fraction of objects exhibiting such a disc/torus structure.