1. The problem statement, all variables and given/known data Determine the mass of the black hole lurking at the center of our galaxy. Conveniently, Nature has arranged for a number of stars to be orbiting the black hole. Star S0-19 has an orbital period of 37 years, and a semimajor axis of 1720 AU. Assume circular orbit and compute the mass of the black hole. Express your answer in solar masses, Msun. What I'm confused about in this problem is if the semi-major axis is the same as the orbital radius? and do I have to convert AU into seconds for solar masses?