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Astronomy quiz question: density wave theory

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

According to the density wave theory, a gas cloud forms new stars as it passes through a spiral arm because:
(A) it slows down and compresses.
(B) it gathers more interstellar material.
(C) it will collide with dark matter.
(D) its metals will break down into non-metals.

Correct answer: (A)

According to the density wave theory, a gas cloud passing through a spiral arm does not collect new material to make new stars, but compresses as it encounters a "traffic jam" located there, which triggers new star formation.

Section 30674
(A) : 31 students
(B) : 3 students
(C) : 1 student
(D) : 2 students

Success level: 76% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.45

This question was asked in Fall semester 2009 as a quiz question.

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