  Motivated by recent neutral hydrogen observations with the VLA, we have
undertaken an investigation into the interaction that produced the well known
merger remnant NGC 7252. Through fully self-consistent N-body simulations, we
are able to reproduce the kinematic character of the HI observations quite
well, including the velocity reversals observed along each tidal tail. In the
simulation these reversals arise from particles which have turned around in
their orbit and are moving to smaller radii. The bases of the tails fall back
quickly to small pericentric distances, while the more distant regions fall
back more slowly to ever increasing pericentric distances. The delayed return
of tidally ejected material may extend over many Gyr. The evolution of this
merger is followed numerically for 800 h^-1 Myr beyond the best fit time. We
find that nearly half of the present tail material, or of order 10^9 h^-2 of
neutral hydrogen and 2x10^9 h^-2 of starlight, will return to within 13 h^-1
kpc of the nucleus within this time span. While the collisionless stars of the
tails will continue orbiting between their inner and outer turning points, the
observations show the HI gas of the tails disappearing upon its return. We
discuss this result in light of the lack of central HI in the main body of this
merger remnant.
