Consider two stars of the same mass: star 1 has just moved on to the main sequence,and star 2 is about to leave it.How are these two stars different?
A)Star 2 has more helium in its core and a hotter surface.
B)Star 2 has more helium in its core and a cooler surface.
C)Star 1 is more luminous and has a hotter surface.
D)Star 1 is more luminous and has a cooler surface.

Question

Quizplus · Accepted Answer

Star 2 has been on the main sequence longer, so it has converted more hydrogen into helium in its core, and as stars age on the main sequence, they generally expand and cool, leading to a cooler surface temperature.

Consider Two Stars of the Same Mass: Star 1 Has