Carbon fusion

Carbon fusion is a kind of nuclear fusion that takes place in dense stars.^[1]

A star needs to be 4 times as massive as Sol, our sun, for its core to get hot and dense enough for Carbon fusion to begin, when the Helium available to fuse has been exhausted.^[1]

References

↑ ^1.0 ^1.1 Jeanette Kazmierczak; Barb Mattson (2023-06-09). "Star Basics". Nasa Science. Retrieved 2026-07-15. A high-mass star goes further. Fusion converts carbon into heavier elements like oxygen, neon, and magnesium, which will become future fuel for the core. For the largest stars, this chain continues until silicon fuses into iron. These processes produce energy that keeps the core from collapsing, but each new fuel buys it less and less time. The whole process takes just a few million years. By the time silicon fuses into iron, the star runs out of fuel in a matter of days. The next step would be fusing iron into some heavier element but doing so requires energy instead of releasing it.

[NasaScience2023-06-09-1] 1.0 ^1.1 Jeanette Kazmierczak; Barb Mattson (2023-06-09). "Star Basics". Nasa Science. Retrieved 2026-07-15. A high-mass star goes further. Fusion converts carbon into heavier elements like oxygen, neon, and magnesium, which will become future fuel for the core. For the largest stars, this chain continues until silicon fuses into iron. These processes produce energy that keeps the core from collapsing, but each new fuel buys it less and less time. The whole process takes just a few million years. By the time silicon fuses into iron, the star runs out of fuel in a matter of days. The next step would be fusing iron into some heavier element but doing so requires energy instead of releasing it.

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