If a star has a temperature twice as hot as the Sun's and a luminosity 32 times the Sun's, what is the ratio of its radius to the Sun's radius?
Group of answer choices
2
5.8
16
1/2
The luminosity of a star is directly proportional to its radius squared and its temperature to the fourth power.
Therefore, if the star has a luminosity 32 times the Sun's and a temperature twice as hot as the Sun's, its radius is √(32) = 4 times that of the Sun.
So, the ratio of the star's radius to the Sun's radius is 4/1 = 4.
The correct answer is not among the given choices.