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The population of debris discs on the main sequence is well constrained, however very little is known about debris discs around evolved stars. In this work we provide a theoretical framework that considers the effects of stellar evolution on debris discs; firstly considering the evolution of an individual disc from the main sequence through to the white dwarf phase, then extending this to the known population of debris discs around main sequence A stars. It is found that discs around evolved stars are harder to detect than on the main sequence. In the context of our models discs should be detectable with Herschel or Alma on the giant branch, subject to the uncertain effect of sublimation on the discs. The best chances are for hot young white dwarfs, fitting nicely with the observations e.g the helix nebula (Su et al.. 2007) and 9 systems presented by Chu & Bilikova (this volume). Although our baseline models do not predict such a high rate of detectable discs. [ABSTRACT FROM AUTHOR]

One of the legacies of IRAS was to show that some 15% of main sequence stars are surrounded by disks of dust. The dust in these debris disks is continually replenished by the destruction of larger planetesimals and so these disks have the potential to tell us a great deal about the outcome of planet formation in their systems. To extract such information the disks need to be resolved. The handful of disks which have had their structure mapped have shown that none of these disks are smooth or axially symmetric. A wide variety of disk structures have been detected, ranging from warped disks of asymmetric brightness to clumpy ring-like disks. Detailed dynamical modeling has identified many of these structures with perturbations from as yet unseen planetary companions. In this paper I review the types of structure that planets can, and indeed have been purported to, impose on debris disks, and look at the evidence we have from modeling of debris disk images that these unseen companions really exist. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]