How do astronomers measure the masses of stars directly?
A) by observing the star's brightness at different wavelengths (colors)
B) by observing the motion of two stars in a binary star system
C) by measuring the star's brightness, temperature, and distance
D) by measuring the star's brightness and obtaining its radius using the H-R diagram

Question

Quizplus · Accepted Answer

Astronomers can measure the masses of stars directly by observing the motion of two stars in a binary star system. The gravitational interaction between the two stars causes them to orbit around their common center of mass. By applying Kepler's laws of planetary motion and Newton's law of universal gravitation, astronomers can calculate the masses of both stars based on their orbital periods and distances from each other. This method is one of the most direct and reliable ways to determine stellar masses.

How Do Astronomers Measure the Masses of Stars Directly