In a particular binary star system, only one star is visible because the other star is too faint to see at that distance. An astronomer measures the size (semimajor axis) and period of the orbit of the visible star. From this information, the astronomer
A) cannot calculate anything about the mass-both stars have to be visible to do so.
B) can calculate the mass of each star.
C) can calculate the sum of the masses of the two stars but not the mass of each star separately.
D) can calculate the mass of the visible star but not that of the unseen star.

Question

Quizplus · Accepted Answer

The mass of each star separately cannot be determined with the given information, but the sum of the masses can be calculated using Kepler's third law, which relates the orbital period and the size of the orbit (semimajor axis) to the total mass of the system.

In a Particular Binary Star System, Only One Star Is