The ESO Multi-Instrument Kinematic Survey (MIKiS) of Galactic Globular
  Clusters: solid body rotation and anomalous velocity dispersion profile in
  NGC 5986
  As part of the ESO-VLT Multi-Instrument Kinematic Survey (MIKiS) of Galactic
globular clusters, we present a detailed investigation of the internal
kinematics of NGC 5986. The analysis is based on about 300 individual radial
velocities of stars located at various distances from the cluster center, up to
300 arcseconds (about 4 half-mass radii). Our analysis reveals the presence of
a solid-body rotation extending from the cluster center to the outermost
regions probed by the data, and a velocity dispersion profile initially
declining with the distance from the cluster's center, but flattening and
staying constant at ~5 km/s for distances larger than about one half-mass
radius. This is the first globular cluster for which evidence of the joint
presence of solid-body rotation and flattening in the outer velocity dispersion
profile is found. The combination of these two kinematical features provides a
unique opportunity to shed light on fundamental aspects of globular cluster
dynamics and probe the extent to which internal relaxation, star escape,
angular momentum transport and loss, and the interaction with the Galaxy tidal
field can affect a cluster's dynamical evolution and determine its current
kinematical properties. We present the results of a series of N-body
simulations illustrating the possible dynamical paths leading to kinematic
features like those observed in this cluster and the fundamental dynamical
processes that underpin them.
