CONICET | Buscador de Institutos y Recursos Humanos

We used a multipolar code to create, through the disipalionless collapsed of systems of 1.000.000 particles, three self-consistent triaxial stellar systems with axial ratios corresponding to those od E4, E5 and E6 galaxies. The E6 model has a small, but significant, rotation velocity although its total angular momentum is zero, that is, it exhibits figure rotation of the E5 model is barely significant and of the E4 model is essentially zero. Except for minor changes, probably caused by unavoidable relaxation effects, the systems are highly stable. The potential of each system was subsequently approximated with interpolating formulae yielding smooth potentials, stationary in the rotating frame for the rotating ones. The Lyapunov exponent could then be computed for randomly selected samples of the bodies that make up the different systems, allowing the recognition of regular and partially and fully chaotic orbits. Finally, the regular orbits were Fourier analyzed and classified using their locations of the frequency map. As it could be expected, the percentages of chaotic orbits increase with the flattening of the system. As one goes from E6 through E4, the fraction of partially chaotic orbits relative to that of fully chaotic ones increases with the former surpasing the latter in model E4; the likely cause of this behavior is that triaxiality diminishes from E6 through E4, the latter system being almost axially symmetric. We especulate that some of the partially chaotic orbits may obey a global integral akin to the long axis component of angular momentum. Our results show that is perfectly possible to have highly stable triaxial model with large fractions of chaotic orbits, but such systems cannot have constant axial ratios from center to border: a slyghtly flattened reservoir of highly chaotic orbits seems to be mandatory for those systems.