Forced eccentricity in circumbinary discs

We analyze the eccentric response of a low mass coplanar circumbinary disc to secular tidal forcing by Keplerian orbit central binary. The acquires forced eccentricity whose magnitude depends on properties binary and disc. largest eccentricities occur when there is global apsidal resonance in driving frequency its that equal zero. A occurs permit existence zero free mode. Resonances for different modes differ number radial nodes. For not at resonance, distribution has somewhat similar form distributions discs have closest matching aspect ratios. higher ratios, 2D fundamental 3D order modes, mode, unless very cool. parameters close large phase shifts between are locked phase. Forced may play an important role evolution their binaries.