Helium fusion
Helium fusion is a kind of nuclear fusion, with the nuclei involved being helium.
The fusion of helium-4 nuclei (alpha particles) is known as the triple-alpha process, because fusion of just two helium nuclei only produces beryllium-8, which is unstable and breaks back down to two helium nuclei with a half-life of 1×10−16 to 2.6×10−16 seconds. If the core temperature of a star exceeds 100 million kelvins (100 megakelvins, 8.6 KeV), as may happen in the later phase of red giants and red supergiants, then a third helium nucleus has a significant chance of fusing with the beryllium-8 nucleus before it breaks down, thus forming carbon-12. Depending upon the temperature and density, an additional helium nucleus may fuse with carbon-12 to form oxygen-16, and at very high temperatures, additional fusions of helium to oxygen and heavier nuclei may occur (see alpha process).
The fusion of helium-3 with itself or with helium-4 occurs during the fusion of hydrogen in main sequence stars (see proton-proton chain), and is not ordinarily referred to as helium fusion.
[edit] See also
[edit] References
- Ray, Alak K. (2004). "Stars as thermonuclear reactors: their fuels and ashes". arΧiv e-print. arXiv:astro-ph/0405568. Bibcode 2004astro.ph..5568R.
