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?

Question

Group of answer choices

2

5.8

16

1/2

Answer 1

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.