On the structure of circumbinary accretion disks and the tidal evolution of commensurable satellites

Abstract

We continue our investigation of tidal torques on accretion disk flows in the vicinity of close binary systems. We demonstrate that the tidal effect can truncate the inner edge of circumbinary accretion discs. If the viscous dissipation is weak in such disks, density enhancement can be produced at the outer Lindblad resonance. We apply our results to contact binaries and the formation of commensurable satellites in the solar system. In order to determine whether the present configurations are a result of formation, or subsequent tidal evolution, we relate the forced eccentricity of resonant satellites, to the Q values of the planet and satellites. We find that while the Galilean satellites may owe their present configuration, in part, to tidal effects, this is unlikely for other commensurable pairs.