The file stars.dat contains the six phase space coordinates of particles
at the last moment of the run described in my paper entitled "A bar model
for the Galactic bulge" in the proceedings of the "Back to the Galaxy"
conference edited by S S Holt & F Verter (New York: AIP press) pp 133--136
(1993). The 6 coordinates for each particle are arranged in the following
order:
z, y, x, vz, vy, vx
These 43802 particles are those which remain inside the calculation box at
time 200 shown in figure 1 of that paper. The units of distance and time
are those used in that figure. A possible scaling is to set the length unit
to 1.33 kpc, the time unit to 4.33 Myr which would give the galaxy at total
mass of 2.77 x 10^{10} Solar masses. The Sun in Figure 1 is placed at an
angle of 30 degrees to the y-axis of these coordinates, which is very nearly
the major axis of the bar, and at a distance of 6 units (or 8 kpc).
The model rotates in a counter-clockwise direction in the projection shown,
whereas the Milky Way has the opposite rotation sense in the usual galactic
coordinates. Figures 2 & 3 of that paper are drawn with the signs of the
x-coordinates reversed to enable more direct comparison with observational
data.
Note that this is NOT a fully self-consistent model because the particles
feel an additional radial force from a rigid spherical mass distribution
that contains 30% of the total mass. This mass distribution has the
form of a Plummer sphere (Binney & Tremaine p42) with the length scale
b equal to one half in these units.
I am not completely happy with this model both because it is not fully
self-consistent and because the vertical thickness is not at all well
resolved by the grid. (The grid has 31 x 127 x 127 cubic boxes.) This is
the reason it is described only in conferences and not in a journal. I
may, one day, try to make a fully self-consistent model with more particles
and better resolution, but I have not found time to work on it for a long
time. Nevertheless, I believe the fraction of mass that is rigid is small
enough, and the in-plane resolution is sufficient, to afford reasonable
comparisons with data obtained from our line of sight towards the bulge.
Fall 1994
Jerry Sellwood