The Sun's absolute magnitude is about +5.The brightest stars in our sky have absolute magnitudes of about -10.What is the luminosity of these stars compared to the Sun,assuming that they have similar spectral light distributions?
A) 1 million times larger
B) 5 times less
C) 1 million times smaller
D) 15 times greater

Question

Quizplus · Accepted Answer

The luminosity of a star compared to another can be calculated using the formula that a difference of 5 magnitudes corresponds to a factor of 100 in brightness. Since the difference here is 15 magnitudes (-10 for the brightest stars vs +5 for the Sun), we calculate the brightness factor as $100^{(15/5)} = 100^3 = 1,000,000$. Thus, these stars are 1 million times more luminous than the Sun.

The Sun's Absolute Magnitude Is About +5