The mass interior to R = 8 kpc is roughly 10^(11) solar masses,
        or M = 2 x 10^(41) kg.  Assume that the hypervelocity
        star has a mass of about 2 solar = 4 x 10^(30) kg.



  Q:  What is the KE of the star?

           KE   =  0.5 * 4 x 10^(30) kg *  [ 1700 x 10^3 m/s ]^2

                =  5.8 x 10^(42) J


  Q:  What is the GPE of the star?

                   6.67 x 10^(-11) N*m^2/kg^2 * 4 x 10^(30) kg * 2 x 10^(41) kg
        GPE  =  - -------------------------------------------------------------
                                  2.46 x 10^(20) m
        
             =  - 2.1 x 10^(41) J



  Q:  Is the total energy positive or negative?

          The total energy is very positive: the KE is over 20 times
               larger in magnitude than the GPE.

          The star would easily escape from this truncated Milky Way.