An exoplanet X X\,X orbits a distant star S S\,S of mass MS M_S\,MS in a stable circular orbit of radius R R\,R with orbital period TTT.
A moon Y Y\,Y orbits the exoplanet X X\,X in a stable circular orbit of radius r=0.010Rr = 0.010 Rr=0.010R.
The mass of the exoplanet is MX=4.0×10−4MSM_X = 4.0 \times 10^{-4} M_SMX=4.0×10−4MS.
What is the orbital period of moon Y Y\,Y around exoplanet X X\,X in terms of TTT?
0.0025T0.0025 T0.0025T
0.050T0.050 T0.050T
0.50T0.50 T0.50T
5.0T5.0 T5.0T
