Astronomy 10 Quiz 12, Spring Semester 2007
Cuesta College, San Luis Obispo, CA
Astronomy 10 learning goal Q12.3
[3.0 points.] Which one of the following choices best describes characteristics expected of the oldest white dwarfs in the disk of the Milky Way?
(A) On the verge of undergoing type Ia supernova explosions.
(B) Dim luminosities and cool surface temperatures.
(C) Extremely metal-rich absorption spectra.
(D) Extremely redshifted absorption spectra.
(E) Extremely low mass.
Correct answer: (B).
White dwarfs are the degenerately packed cores of giants, after the outer layers have been shed during the planetary nebula phase. Since there is no more energy source for an isolated white dwarf, it will gradually cool off and become dimmer in luminosity, according to the Stefan-Boltzmann law (luminosity proportional size times temperature^4), where size remains constant.
Student responses
Section 4136
(A) : 5 students
(B) : 16 students
(C) : 7 students
(D) : 5 students
(E) : 2 students
Section 5076
(A) : 1 student
(B) : 13 students
(C) : 6 students
(D) : 5 students
(E) : 1 student
