Q:  Consider a star like the Sun, in the disk of the Milky Way Galaxy.


         What is a reasonable value for b_min?

             We concluded that the Sun would move by around 3 AU
             during one encounter, and b_min should be much larger
             than this shift, so ... maybe 30 AU.  Maybe 100 AU.


         What is a reasonable value for b_max?

             One choice: the thickness of the disk of the Milky Way,
             around 1 kpc.  This is a good choice, as the distribution
             of stars around the Sun is at least roughly spherically
             symmetric out this far.


             Another choice might be the diameter of the Milky Way,
             around 30-50 kpc.  This is probably not as good a choice,
             as the density of stars is NOT uniform in all directions
             around the Sun at this scale.