A neutron star (2.5 solar masses) is seen orbiting a bright blue star once every 0.55 years at a distance of 2.0 AU. The mass of the blue star is ______ solar masses? Solution T = 2 * pi * sqrt(a^3 / Gu) where u=m1m2/m1+m2 u=2.4 solar mass hence mass of blue star=60 solar mass.