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We study the tidal disruption of binaries by a massive point mass (e.g. theblack hole at the Galactic center), and we discuss how the ejection and capturepreference between unequal-mass binary members depends on which orbit theyapproach the massive object. We show that the restricted three-bodyapproximation provides a simple and clear description of the dynamics. Theorbit of a binary with mass m around a massive object M should be almostparabolic with an eccentricity |1-e| < (m/M)^{1/3} << 1 for a member to becaptured, while the other is ejected. Indeed, the energy change of the membersobtained for a parabolic orbit can be used to describe non-parabolic cases. Ifa binary has an encounter velocity much larger than (M/m)^{1/3} times thebinary rotation velocity, it would be abruptly disrupted, and the energy changeat the encounter can be evaluated in a simple disruption model. We evaluate theprobability distributions for the ejection and capture of circular binarymembers and for the final energies. In principle, for any hyperbolic (elliptic)orbit, the heavier member has more chance to be ejected (captured), because itcarries a larger fraction of the orbital energy. However, if the orbital energyis close to zero, the difference between the two members becomes small, andthere is practically no ejection and capture preference. The preference becomessignificant when the orbital energy is comparable to the typical energy changeat the encounter. We discuss its implications to hypervelocity stars andirregular satellites around giant planets.

Ejection and Capture Dynamics in Restricted Three-Body Encounters