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 = 2 $\pi$r/v.
B) the distances of the Doppler shift points from its center.
C) both answers A and B
D) It is impossible to estimate the mass of M31.

Question

Quizplus · Accepted Answer

The rotation curve method involves measuring the rotation velocity of material at different distances from the center of the galaxy and using this to construct a rotation curve. By assuming an equilibrium between the gravitational force on the material and the centripetal force required to maintain its circular motion, we can estimate the total mass enclosed within each radius. This method requires both the Doppler shifts of the material and the distances at which they are observed, so the correct answer is C.

Via the Rotation Curve Method, We Can Estimate the Mass π\piπ

Via the Rotation Curve Method, We Can Estimate the Mass $\pi$