Determining the type of orbits in the central regions of barred galaxies
  We use a simple dynamical model which consists of a harmonic oscillator and a
spherical component, in order to investigate the regular or chaotic character
of orbits in a barred galaxy with a central spherically symmetric nucleus. Our
aim is to explore how the basic parameters of the galactic system influence the
nature of orbits, by computing in each case the percentage of chaotic orbits,
as well as the percentages of different types of regular orbits. We also give
emphasis to the types of regular orbits that support either the formation of
nuclear rings or the barred structure of the galaxy. We provide evidence that
the traditional x1 orbital family does not always dominate in barred galaxy
models since we found several other types of resonant orbits which can also
support the barred structure. We also found that sparse enough nuclei, fast
rotating bars and high energy models can support the galactic bars. On the
other hand, weak bars, dense central nuclei, slowly rotating bars and low
energy models favor the formation of nuclear rings. We also compare our results
with previous related work.
