Fractal basins of escape and the formation of spiral arms in a galactic
  potential with a bar
  We investigate the dynamics in the close vicinity of and within the critical
area in a 2D effective galactic potential with a bar of Zotos. We have
calculated Poincar\'e surfaces of section and the basins of escape. In both the
Poincar\'e surfaces of section and the basins of escape we find numerical
evidence for the existence of a separatrix which hinders orbits from escaping
out of the bar region. We present numerical evidence for the similarity between
spiral arms of barred spiral galaxies and tidal tails of star clusters.
