## 2. Barred galaxy potentialFor the sake of comparison, the barred galaxy potential used here
is the one described in Pfenniger 1984 (P84). As often verified, the
precise density shape far from the considered orbits is not important
when describing the major orbits of a galactic potential: indeed their
shapes depend mostly on the main The potential derives from two mass components, a Miyamoto-Nagai (1975) disc, whose potential reads, and a triaxial Ferrers (1877) bar of
semi-axes where The corresponding potential and forces are
given in a closed form suited for numerical treatment in P84
The main change with the "main model" in P84 is the adoption of a much thicker, nearly prolate bar ( instead of 10), less eccentric ( instead of 4), but more massive ( instead of 0.1), so that the bar strength remains similar. The first reason to adopt a nearly prolate bar is that the belief
in the 80's that bars should be very flat in The second reason to choose a more massive but less eccentric bar
is that the stability properties of the Lagrangian points
are then compatible to those found in The prime goal to reach with this potential, i.e. to get a relatively realistic mass model computable with precision but without excessive compromise linked with easily tractable analytical formulae, is then achieved. The length unit can be conveniently taken as the kpc, the time unit as , and the mass unit of the order of . © European Southern Observatory (ESO) 1998 Online publication: June 2, 1998 |