A star whose absolute magnitude M is +2.2 is seen to have an apparent magnitude when viewed from Earth of +5.2. How far away is the star?
A) 40 pc
B) 12.3 pc
C) 130 pc
D) 3/5, or 0.6 pc

Question

Quizplus · Accepted Answer

The distance to the star can be calculated using the distance modulus formula: $m - M = 5 \log(d) - 5$, where $m$ is the apparent magnitude, $M$ is the absolute magnitude, and $d$ is the distance in parsecs. Plugging in the given magnitudes ($m = 5.2$, $M = 2.2$), we solve for $d$ and find it to be approximately 40 parsecs.

A Star Whose Absolute Magnitude M Is +2