Heavier stars die younger, which runs against the hunch that more fuel means a longer burn. Between 0.2 and 32 solar masses, a red dwarf crawls along and lasts trillions of years, longer than the present age of the universe, while a 12-solar-mass star burns out in roughly 20 million years and explodes. That whole life traces a real path across the H-R diagram: off the main sequence, onto the red-giant branch, then down into the white-dwarf corner.
Heavier stars die younger, which runs against the hunch that more fuel means a longer burn. Between 0.2 and 32 solar masses, a red dwarf crawls along and lasts trillions of years, longer than the present age of the universe, while a 12-solar-mass star burns out in roughly 20 million years and explodes. That whole life traces a real path across the H-R diagram: off the main sequence, onto the red-giant branch, then down into the white-dwarf corner.
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