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

Abstract

Tidal torques on accretion disk flows in the vicinity of close binary systems are investigated. It is demonstrated that tidal effects can truncate the inner edge of circumbinary accretion disks. If the viscous dissipation is weak in such disks, density enhancement can be produced at the outer Lindblad resonance. The results are applied 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, the forced eccentricity of resonant satellites is related to the Q values of the planet and satellites. It is found that while the Galilean satellites may owe their present configuration, in part, to tidal effects, this is unlikely for other commensurable pairs.