Cuesta College, San Luis Obispo, CA
The distances and absolute magnitudes of two stars are listed below.
| d distance (parsecs) |
M absolute magnitude |
|
| Gliese 556 | 44 pcs | +7.3 |
| θ Ursae Majoris | 44 pcs | +3.0 |
When placed at 10 parsecs away, the star that is brightest is:
(A) Gliese 556.
(B) θ Ursae Majoris.
(C) (There is a tie.)
(D) (Not enough information is given.)
Correct answer (highlight to unhide): (B)
The absolute magnitude of a star is the brightness it has when placed 10 parsecs away from Earth. Since θ Ursae Majoris has an absolute magnitude of +3.0 that is brighter than Gliese 556's absolute magnitude of +7.3 (as larger positive magnitude values correspond to dimmer brightnesses), if both stars were placed 10 parsecs away from Earth, θ Ursae Majoris will appear to be brighter in the night sky.
Section 70160
Exam code: quiz05Oor7
(A) : 1 student
(B) : 13 students
(C) : 2 students
(D) : 1 student
Success level: 78% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.20
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