A galaxy rotation curve is a plot of the rotation speed as a function of the:
A) galaxy's luminosity
B) mass of the dark matter halo
C) brightness of the luminous matter in the galaxy
D) radius from the center
E) ages of star clusters

Question

Quizplus · Accepted Answer

A galaxy rotation curve is a plot of the rotation speed as a function of the radius from the center. This helps astronomers understand the distribution of dark matter in galaxies. The rotation speed helps to determine the amount of mass present at different radii, and comparing this to the visible mass (brightness of the luminous matter in the galaxy) can reveal the presence of dark matter. The luminosity of the galaxy or the ages of star clusters are not directly related to the rotation speed.

A Galaxy Rotation Curve Is a Plot of the Rotation