The star Alderamin has an apparent magnitude of 2.4 and an absolute magnitude of 1.4.From this information (assuming that the starlight has not been dimmed by interstellar clouds),we can say for sure that Alderamin is _____ away.
A) less than 10 pc
B) less than 10 ly
C) more than 10 ly
D) more than 10 pc

Question

Quizplus · Accepted Answer

The distance modulus formula relates apparent magnitude, absolute magnitude, and distance in parsecs. Since Alderamin's apparent magnitude is greater than its absolute magnitude, it must be more than 10 parsecs away.

The Star Alderamin Has an Apparent Magnitude of 2