A star that is 100 pc distant from Earth has an apparent magnitude of m +2.5.According to the equation in Discovery 10-2 in Comins,Discovering the Essential Universe,6th ed.,what is its absolute magnitude?
A) -7.5
B) +7.5
C) -2.5
D) -47.5

Question

Quizplus · Accepted Answer

The absolute magnitude (M) can be calculated using the distance modulus formula: M = m - 5(log10(d) - 1), where m is the apparent magnitude and d is the distance in parsecs. For a star 100 pc away with m = +2.5, M = 2.5 - 5(log10(100) - 1) = 2.5 - 5(2 - 1) = 2.5 - 5 = -2.5.

A Star That Is 100 Pc Distant from Earth Has