Astronomy quiz question: black hole in binary star system

Astronomy 210 Quiz 5, Fall Semester 2010
Cuesta College, San Luis Obispo, CA

A compact object with __________ may be evidence of a black hole in a binary system.
(A) a hot, x-ray emitting accretion disk.
(B) regularly timed x-ray pulses.
(C) zero mass and no emitted light.
(D) repeated nova bursts.

Correct answer: (A)

Response (B) is evidence of a neutron star (pulsar) in a binary system; response (D) is evidence of a white dwarf in a binary system. Response (C) is not true for black holes (which have a finite mass, but zero size, and emit light from their accretion disks). Note that response (A) is also evidence of white dwarfs and neutron stars in binary systems, as they also have accretion disks.

Section 70160
(A) : 14 students
(B) : 4 students
(C) : 16 students
(D) : 0 students

"Success level": 46% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.78