Q:  What is the velocity of star B?


          One can go through exactly the same procedure as for star A ...
          or one can recognize that it has the same period, but an orbital
          radius which is larger by


               R_B        M_A          15
             -------  =  ------   =   -----
               R_A        M_B           1


          which means that the velocity must also be larger by the same
          factor:

                 V_B  =  15 V_A   =    367 km/s