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The Hertzsprung-Russell Diagram
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Astronomy
AST.195 The Hertzsprung-Russell Diagram
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Why can a red giant be far more luminous than the Sun even though its surface is cooler?
A
It is less luminous but appears bright only because it is red
B
Its much larger radius gives it far more surface area to radiate light
C
It has no relationship between radius and luminosity
D
Its surface temperature is actually much hotter than the Sun's
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