Via the rotation curve method, we can estimate the mass of galaxies like M31 from
A)Doppler shifts of material at the edge of its disk and computing P = 2πr/v.
B)the distances of the Doppler shift points from its center.
C)Doppler shifts of material at the edge of its disk and computing P = 2πr/v and the distances of the Doppler shift points from its center.
D)It is impossible to estimate the mass of M31.

Question

Quizplus · Accepted Answer

The rotation curve method involves measuring Doppler shifts of material at the edge of a galaxy's disk and using the equation P = 2πr/v to determine the mass enclosed within a given radius. By measuring the distances of the Doppler shift points from the center of the galaxy, we can trace out the shape of the rotation curve and estimate the total mass of the galaxy. Choice C includes both of these elements and is therefore the best choice.

Via the Rotation Curve Method, We Can Estimate the Mass