Helium Capture

Formation of heavy elements by the capture of helium nuclei. For example, at ~6 x 108 K, carbon can form heavier elements by fusion with other carbon nuclei:

However, fusion is more likely to occur by helium capture, which requires less energy and lower temperatures (~2 x 108 K):

Similarly, 16O may fuse with other 16O nuclei at ~109 K to form 32S, but it is much more probable that 16O will capture a 4He nucleus (if one is available) to form 20Ne. Again, 4He capture is more likely because it requires a lower temperature. Elements with nuclear masses of 4, 12, 16, 20, 24, and 28 have much higher abundances than other isotopes.

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