2005MNRAS.358..305P

We investigate the morphological relation between the orbits of the central family of periodic orbits (x₁family) and the bar itself using models of test particles moving in a barred potential. We show that different bar morphologies may have as a backbone the same set of x₁ periodic orbits. We point out that by populating initially axisymmetric stellar discs exponentially with test particles in circular, or almost circular motion, we may end up with a response bar which reveals a shape different in crucial details from that of the individual stable x₁orbits. For example, a bar model in which the x₁orbits are pure ellipses may have a much more complicated response morphology. This depends on the particular invariant curves around x₁, which are populated in each model.