Why is a 1 solar- mass red giant more luminous than a 1 solar- mass main sequence star?
A)Fusion reactions are producing energy at a greater rate in the red giant.
B)The red giant is more massive.
C)The red giant has a hotter core.
D)The red giant's surface is hotter.

Question

Quizplus · Accepted Answer

A red giant is more luminous than a main sequence star because it has exhausted the hydrogen fuel in its core and has moved on to fusing heavier elements. Fusion reactions producing energy at a greater rate account for its higher luminosity.

Why Is a 1 Solar- Mass Red Giant More Luminous