| Description |
We propose to use the Herschel-PACS/SPIRE instruments to study the far-infrared spectral properties of a sample of bright evolved binary stars. All these stars are surrounded by a dusty circumbinary disc in a stable Keplerian orbit. Mid-infrared spectroscopic studies show that these discs are the ideal environmentfor strong dust processing, in the form of grain growth and crystallinisation. Detailed disc modelling shows that the discs are not only very dusty, but also that a non-negligible gas component must be present, to allow for the observed disc geometry. The spectroscopic capabilities of Herschel will allow to extend the spectroscopic information to the far-infrared, allowing the detection of previously unexplored or unexpected dust and gas features. This will provide invaluable information on the dust processing in the disc, and the relatively unstudied gas component. |
