When stars leave the main-sequence group,their core hydrogen is depleted and they become
A) brighter and cooler.
B) brighter and hotter.
C) dimmer and cooler.
D) dimmer and hotter.

Question

Quizplus · Accepted Answer

When stars exhaust their core hydrogen, they expand and their surface cools down, making them brighter due to their increased size but cooler in terms of surface temperature.

When Stars Leave the Main-Sequence Group,their Core Hydrogen Is Depleted