Spectroscopy of Red Giants in the globular cluster Terzan 8: kinematics
  and evidence for the surrounding Sagittarius stream
  We present the results of a spectroscopic survey of Red Giants in the
globular cluster Terzan 8 with the aim of studying its kinematics. We derived
accurate radial velocities for 82 stars located in the innermost 7 arcmin from
the cluster center identifying 48 bona fide cluster members. The kinematics of
the cluster have been compared with a set of dynamical models accounting for
the effect of mass segregation and a variable fraction of binaries. The derived
velocity dispersion appears to be larger than that predicted for
mass-segregated stellar systems without binaries, indicating that either the
cluster is dynamically young or it contains a large fraction of binaries
(>30%). We detected 7 stars with a radial velocity compatible with the cluster
systemic velocity but with chemical patterns which stray from those of both the
cluster and the Galactic field. These stars are likely members of the
Sagittarius stream surrounding this stellar system.
