Roche lobes

Roche lobes

[′rōch ‚lōbz] (mechanics) Regions of space surrounding two massive bodies revolving around each other under their mutual gravitational attraction, such that the gravitational attraction of each body dominates the lobe surrounding it. In particular, the effective potential energy (referred to a system of coordinates rotating with the bodies) is equal to a constant V0 over the surface of the lobes, and if a particle is inside one of the lobes and if the sum of its effective potential energy and its kinetic energy is less than V0, it will remain inside the lobe.