20130322

Astronomy quiz question: O5 main-sequence star vs. M5 giant

Astronomy 210 Quiz 4, spring semester 2013
Cuesta College, San Luis Obispo, CA

An O5 main-sequence star will be __________ compared to a M5 giant.
(A) smaller and dimmer.
(B) smaller and brighter.
(C) larger and dimmer.
(D) larger and brighter.

Correct answer: (B)

Using an H-R diagram (provided on this quiz, to be filled in by the students with the given information as below), the O5 white dwarf is smaller (10 RSun vs. 110 RSun), brighter (1,000,000 LSun vs. 1,000 LSun), and hotter (50,000 K vs. 2,500 K), than the M5 giant.

Section 30674
Exam code: quiz04Ni7E
(A) : 1 student
(B) : 16 students
(C) : 3 students
(D) : 7 students
(No response: 1 student)

Success level: 60% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.50

Section 30676
Exam code: quiz04sGf6
(A) : 6 students
(B) : 24 students
(C) : 2 students
(D) : 10 students

Success level: 60% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.73

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