Orbital Structure in Barred Galaxies and the Role of Chaos

We study the orbital structure of a self-consistent N-body configuration of a barred galaxy, having a value of spin parameter near the one of our Galaxy. We find that 60% of the orbits are chaotic. We examine the phase space using 2-D projections of the surfaces of section for test; particles as well as for real N-body particles. The real particles are not uniformly distributed in the whole phase space but they avoid orbits that do not support the bar. We use frequency analysis for the regular as well as for the chaotic orbits to classify certain types of orbits. We find the main resonant orbits and their statistical weight in supporting the shape of the bar emphasizing the role of weekly chaotic orbits. Finally we show that the effectiveness of Arnold diffusion is restricted.