2016MNRAS.461.1404F

The most accurate six-dimensional (6D) phase-space information from the Radial Velocity Experiment (RAVE) was used to integrate the orbits of 105 stars around the galactic globular cluster 47 Tucanae, to look for close encounters between them in the past with a minimum distance approach less than the cluster tidal radius. The stars are currently spread over the distance range 3.0 kpc < d < 5.5 kpc. Using the uncertainties in the current position and velocity vector for both stars and cluster, 105 pairs of star-cluster orbits were generated in a Monte Carlo numerical scheme, integrated over 2 Gyr and considering an axisymmetric and non-axisymmetric Milky-Way-like Galactic potential, respectively. In this scheme, we identified 20 potential cluster members that had close encounters with the globular cluster 47 Tucanae, all of which have a relative velocity distribution (V_rel) less than 200 km/s at the minimum distance approach. Among these potential members, nine had close encounters with the cluster with velocities less than the escape velocity of 47 Tucanae; therefore a scenario of tidal stripping seems likely. These stars have been classified with a 93 per cent confidence level, leading to the identification of extratidal cluster stars. For the other 11 stars, V_rel exceeds the escape velocity of the cluster; therefore likely they were ejected or are unassociated interlopers.