Measurements indicate that a certain star has a very high intrinsic brightness (100,000 times as bright as the Sun)and yet is relatively cool (3500 K).How can this be?
A) The star must be quite small.
B) The star must be very large.
C) There must be an error in observation because no star can have these properties.
D) The star must be in the upper part of the main sequence.

Question

Quizplus · Accepted Answer

The star must be very large because its high intrinsic brightness indicates a large amount of energy being released, but its relatively cool temperature appears to contradict this. However, this can be explained by the fact that larger stars have a lower surface area-to-volume ratio, which means that a large amount of energy is produced in the core but takes longer to be radiated away from the surface. This results in a cooler surface temperature despite the high intrinsic brightness.

Measurements Indicate That a Certain Star Has a Very High