Two stars have the same diameter and are at the same distance from us (but in different parts of the sky.) Star A has a temperature of 4000 K, while star B has a temperature of 8000K. Which of the following statements is true:
A) the two stars have the same total energy flux (luminosity)
B) star B has twice the energy flux (luminosity) that star A has
C) star B has one half the energy flux (luminosity) that star A has
D) star B has 16 times the energy flux (luminosity) that star A has
E) Sorry, professor, we don't have enough information to compare the energy flux (luminosity) of the two stars
Section 5.3: Spectroscopy in Astronomy

Question

Quizplus · Accepted Answer

The total energy flux (luminosity) emitted by a star is proportional to the fourth power of its temperature according to the Stefan-Boltzmann law. Therefore, star B, which has twice the temperature of star A, will have 16 times the energy flux (luminosity) that star A has (2^4 = 16).

Two Stars Have the Same Diameter and Are at the Same