The orbital content of bars: The origin of 'non-x1-tree', bar-supporting
  orbits
  Recently, many orbital studies in barred galaxy potentials have revealed the
existence of orbits which are not trapped around x1 tree orbits, but could be
potentially appropriate building blocks for bars. These findings question the
uniqueness of the x1 family as the standard paradigm of orbital motion in
galactic bars. The main goal of this paper is to investigate the role that such
orbits could play in shaping the morphology of bars. We trace the morphological
patterns appearing in the face-on and edge-on views of the non-periodic orbits
presented in these studies and we show that they are introduced in the system
by second type bifurcations of x1. For this purpose, we use a typical 3D
Ferrers bar model and follow the radial and vertical bifurcations of the x1
family considered as being multi periodic, with multi = 2, 3, 5. The variation
of the stability indices of x1 in the multi = 2, 3 cases give us also the four-
and six- periodic orbits, respectively. We tabulate these orbits including all
information necessary to assess their role as appropriate building blocks. We
discuss their stability and their extent, as well as their size and
morphological evolution, as a function of energy. We conclude that even the
most important of the multi-periodic orbits presented in Tables 2 to 5 are less
appropriate building blocks for bars than the families of the x1 tree at the
same energy.
