A pair of stars orbit around one another in an elliptical orbit with a semi-major axis, a, of 1 AU with an orbital period, P, of 1 year. What is the mass of the pair of stars
A)1 solar masses
B)2 solar masses
C)4 solar masses
D)8 solar masses
E)16 solar masses

Question

Quizplus · Accepted Answer

The mass of the pair of stars can be determined using Kepler's third law, which relates the orbital period and the semi-major axis of the orbit to the mass of the two bodies. For a semi-major axis of 1 AU and an orbital period of 1 year, this corresponds to the system having a mass of 1 solar mass, assuming the units are in terms of the Earth's orbit around the Sun.

A Pair of Stars Orbit Around One Another in an Elliptical