Large Velocity Gradients in the Tidal Tails of the Interacting Galaxy AM 1353-272 (The Dentist's Chair)

We present Very Large Telescope observations of the interacting system AM 1353-272. Using the FORS2 instrument, we studied the kinematics of the ionized gas along its prominent tidal tails and discovered strikingly large velocity gradients associated with seven luminous tidal knots. These kinematical structures cannot be caused by streaming motion and most likely do not result from projection effects. More probably, instabilities in the tidal tails have led to the formation of kinematically decoupled objects that could be the progenitors of self-gravitating tidal dwarf galaxies.