Influence of Dynamical Friction on the Unstable Manifolds of Lagrange Points in Barred Galaxies

ABSTRACT Some time ago the idea has been proposed that rings and spirals in barred galaxies are shaped by the unstable manifolds of the Lagrange points sitting near the ends of the bar. The topic of the present article is an investigation of whether the numerical support for this suggestion can be improved by the inclusion of dynamical friction into the equations of motion. We obtain numerical indications for an affirmative answer to this question. In particular, we investigate the effect of dynamical friction on trajectories of test particles starting close to the Lagrange points and the dependence on the strength of the friction and on the length of the bar.