The mass of a visual binary pair of stars can be obtained from
A)the time in years for them to orbit one another.
B)the size of their orbit.
C)their apparent magnitudes.
D)both the time in years for them to orbit one another and the size of their orbit.

Question

Quizplus · Accepted Answer

The mass of a visual binary pair of stars can be obtained from both the time in years for them to orbit one another and the size of their orbit. The relationship between the mass of the stars and the time and size of the orbit is described by Kepler's laws of planetary motion. By measuring the time it takes for a binary pair to complete one orbit and the size of their orbit, astronomers can calculate their masses using Kepler's laws. Apparent magnitudes do not provide information about the mass of the stars.

The Mass of a Visual Binary Pair of Stars Can