The complex kinematics of rotating star clusters in a tidal field
  We broaden the investigation of the dynamical properties of tidally
perturbed, rotating star clusters by relaxing the traditional assumptions of
coplanarity, alignment, and synchronicity between the internal and orbital
angular velocity vector of their initial conditions. We show that the interplay
between the internal evolution of these systems and their interaction with the
external tidal field naturally leads to the development of a number of
evolutionary features in their three-dimensional velocity space, including a
precession and nutation of the global rotation axis and a variation of its
orientation with the distance from the cluster centre. In some cases, such a
radial variation may manifest itself as a counter-rotation of the outermost
regions relative to the inner ones. The projected morphology of these systems
is characterized by a non-monotonic ellipticity profile and, depending on the
initial inclination of the rotation axis, it may also show a twisting of the
projected isodensity contours. These results provide guidance in the
identification of non-trivial features which may emerge in upcoming
investigations of star cluster kinematics and a dynamical framework to
understand some of the complexities already hinted by recent observational
studies.
