Kinematical evolution of tidally limited star clusters: the role of
  retrograde stellar orbits
  The presence of an external tidal field often induces significant dynamical
evolutionary effects on the internal kinematics of star clusters. Previous
studies investigating the restricted three-body problem with applications to
star cluster dynamics have shown that unbound stars on retrograde orbits (with
respect to the direction of the cluster's orbit) are more stable against escape
than prograde orbits, and predicted that a star cluster might acquire
retrograde rotation through preferential escape of stars on prograde orbits. In
this study we present evidence of this prediction, but we also illustrate that
there are additional effects that cannot be accounted for by the preferential
escape of prograde orbits alone. Specifically, in the early evolution,
initially underfilling models increase their fraction of retrograde stars
without losing significant mass, and acquire a retrograde angular velocity. We
attribute this effect to the development of preferentially eccentric/radial
orbits in the outer regions of star clusters as they are expanding into their
tidal limitation.
  We explore the implications of the evolution of the fraction of prograde and
retrograde stars for the evolution of the cluster internal rotation, and its
dependence on the initial structural properties. Although all the systems
studied here evolve towards an approximately solid-body internal rotation with
angular velocity equal to about half of the angular velocity of the cluster
orbital motion around the host galaxy, the evolutionary history of the radial
profile of the cluster internal angular velocity depends on the cluster initial
structure.
