Kinematics



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Kinematics

Observations of proper motions of bulge stars in Baade's window (Spaenhauer et al. 1992) and also radial velocities (Terndrup 1992, Rich et al. in preparation) suggest that the Milky Way bulge has a nearly isotropic velocity distribution.

Data from the model are shown in Figure 3, which gives the dispersions of particle velocities along the line of sight and in the perpendicular component parallel to the galactic plane in the central few degrees. (The dispersion normal to the plane is not shown, but is substantially lower than for either component in the plane. Part of this anisotropy can be attributed to the grid-based numerical technique, in which forces are weaker than Newtonian at short range, having a disproportionately large effect on the vertical restoring force.) From this viewing angle, the perpendicular component is a little larger than the line-of-sight component; the difference would be less from a smaller viewing angle, however.



Peter Teuben
Wed Feb 8 15:23:27 EST 1995