Astronomy quiz question: dark matter locations

Astronomy 210 Quiz 6, Fall Semester 2010
Cuesta College, San Luis Obispo, CA

Dark matter in the Milky Way is located:
(A) between the spiral arms.
(B) above and below the disk, in the halo.
(C) in supergiant cores.
(D) inside the central supermassive black hole.

Correct answer: (B)

In order for all stars to have nearly the same orbital speed at different distances from the center of the Milky Way, mass must be distributed evenly as dark matter above and below the Milky Way disk, out in the halo.

Section 70160
(A) : 15 students
(B) : 19 students
(C) : 0 students
(D) : 3 students

"Success level": 55% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.39