Carbon Burning

Fusion reactions between any nuclei larger than C require such high temperatures that they are actually quite uncommon in stars and formation of most heavier elements occurs by addition of He nuclei (the α process). For example, the repulsive force between two C nuclei is three times greater than the force between the nuclei of C and He. Thus, C-He fusion occurs at a lower temperature than C-C.

Some or all content above used with permission from J. H. Wittke.