Cuesta College, San Luis Obispo, CA
The distances and absolute magnitudes of two stars are listed below.
| d distance (parsecs) |
M absolute magnitude |
|
| α Centauri | 1.3 pcs | +5.7 |
| 70 Ophiuchi | 5.1 pcs | +5.7 |
When placed at 10 parsecs away, the star that is brightest is:
(A) α Centauri.
(B) 70 Ophiuchi.
(C) (There is a tie.)
(D) (Not enough information is given.)
Correct answer (highlight to unhide): (C)
The absolute magnitude of a star is the brightness it has when placed 10 parsecs away from Earth. Since α Centauri and 70 Ophiuchi have the same absolute magnitude value, if both stars were placed 10 parsecs away from Earth, they will appear equally bright in the night sky.
Section 70158
Exam code: quiz05T3rA
(A) : 6 students
(B) : 3 students
(C) : 24 students
(D) : 0 students
Success level: 74% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 1
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