You Have Discovered a Star System Consisting of Three Equally

Multiple Choice

You have discovered a star system consisting of three equally spaced stars of equal mass arranged in a straight line. The two outermost stars, Zenith and Nadir, revolve synchronously around the central star, Janus. What is the period of revolution for this system in terms of M, the mass of each of the stars, and R, the radius of the circular orbit of Zenith and Nadir?

A) [2πR^3/2/(GM) ^1/2] × (3/2) ^1/2
B) [2πR^3/2/(GM) ^1/2] × (2/3) ^1/2
C) [2πR^3/2/(GM) ^1/2] × (4/5) ^1/2
D) [2πR^3/2/(GM) ^1/2] × (5/4) ^1/2
E) [2πR^3/2/(GM) ^1/2] × (7/5) ^1/2