Astronomy quiz question: globular cluster star formation

Astronomy 10 Quiz 11, Spring Semester 2008
Cuesta College, San Luis Obispo, CA

Astronomy 10 learning goal Q11.5

[3.0 points.] Which one of the following statements best explains why there are no young stars in the halo clusters of the Milky Way?
(A) There are no longer enough heavy elements remaining in the halo.
(B) There are not enough gravitational forces in the halo for new stars to form.
(C) The dark matter in the halo prevents new stars from forming there.
(D) All of the metal-rich stars in the halo clusters have already become metal-poor stars.
(E) All of the interstellar hydrogen in the halo moved into the disk.

Correct answer: (E)

According to the monolithic formation theory of the Milky Way, the gas and dust in our galaxy was originally spherically shaped. Then as the first-generation stars of the globular clusters formed, hydrogen in the Milky Way gradually collapsed into the thin disk structure that it has today. Thus no new stars can form in the relatively empty spherical halo that surrounds the flattened Milky Way.

Student responses
Section 5166
(A) : 3 students
(B) : 16 students
(C) : 6 students
(D) : 7 students
(E) : 18 students