Central Dynamics of Multi-mass Rotating Star Clusters
  We investigate the evolutionary nexus between the morphology and internal
kinematics of the central regions of collisional, rotating, multi-mass stellar
systems, with special attention to the spatial characterisation of the process
of mass segregation. We report results from idealized, purely $N$-body
simulations that show multi-mass, rotating, and spherical systems rapidly form
an oblate, spheroidal massive core, unlike single-mass rotating or multi-mass
non-rotating configurations with otherwise identical initial properties,
indicating that this evolution is a result of the interplay between the
presence of a mass spectrum and angular momentum. This feature appears to be
long-lasting, preserving itself for several relaxation times. The degree of
flattening experienced by the systems is directly proportional to the initial
degree of internal rotation. In addition, this morphological effect has a clear
characterisation in terms of orbital architecture, as it lowers the inclination
of the orbits of massive stars. We offer an idealised dynamical interpretation
that could explain the mechanism underpinning this effect and we highlight
possible useful implications, from kinematic hysteresis to spatial distribution
of dark remnants in dense stellar systems.
