Tau Ceti: our nearest cousin
Résumé
The 10 Gyr old G8V star τCeti is the closest Solar analogue. It harbors the less massive exo-Kuiper belt detected so far among debris disks stars. With a total disk mass only ten times larger than that of our Kuiper belt, it represents a case study of evolved debris disks. Whether its disk has been continuously eroded by steady-state collisions of planetesimals or recently regenerated by a dynamical instability remains a puzzling question. The detection of the dust points to the existence of (undetected) planetary bodies, which are expected to sculpt the belt and may scatter material inwards to the terrestrial planet region, where hot dust is also observed. Unfortunately, the disk morphology remains unknown. We report a recent Herschel PACS (70μ and 160μ)detection of a 15 au ring-like structure which is in conflict with the earlier SCUBA discovery. The disk is partly resolved by Herschel and we derive its morphology and the dust properties from the images and SED analysis with the GraTer modeling code. τCeti is a unique laboratory to highlight the long-term dynamical evolution of planetary systems and may represent an alternative outcome to the evolution of our Solar system.