Oscillatory Instability in Saturn's Rings - Theory and Observation

Juergen Schmidt (Uni. of Potsdam)

Salle D18 (2e étage) à l'ENS, 24 rue Lhomond, 13:00 à 13:45

The Keplerian shear flow of a dense planetary ring has been predicted to develop spontaneously radial waves on the 100m scale, due to an instability that arises from an interplay of inertial forces and viscous stress. Data from the ongoing Nasa/Esa mission CASSINI to Saturn shows such modes. Here I review theoretical concepts in the light of the CASSINI data. Particularly important is the role of self-gravity of the ring material and the connection to the damping of density waves in the rings which are excited at the inner Lindblad resonances of Saturnian satellites.