  We investigate the regular or chaotic nature of star orbits moving in the
meridional plane of an axially symmetric galactic model with a disk and a
spherical nucleus. We study the influence of some important parameters of the
dynamical system, such as the mass and the scale length of the nucleus, the
angular momentum or the energy, by computing in each case the percentage of
chaotic orbits, as well as the percentages of orbits of the main regular
resonant families. Some heuristic arguments to explain and justify the
numerically derived outcomes are also given. Furthermore, we present a new
method to find the threshold between chaos and regularity for both Lyapunov
Characteristic Numbers and SALI, by using them simultaneously.
