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One analogy is to think of helium-4 as ash, and the amount of ash that one forms when one completely burns a piece of wood is insensitive to how one burns it. The resort to the BBN theory of the helium-4 abundance is necessary as there is far more helium-4 in the universe than can be explained by stellar nucleosynthesis. In addition, it ...
The stability of helium-4 is the reason that hydrogen is converted to helium-4, and not deuterium (hydrogen-2) or helium-3 or other heavier elements during fusion reactions in the Sun. It is also partly responsible for the alpha particle being by far the most common type of baryonic particle to be ejected from an atomic nucleus; in other words ...
Nucleosynthesis is the process that ... especially those with isotopes composed of whole numbers of helium-4 ... Lemaître's model was needed to explain the existence ...
As a side effect of the process, some carbon nuclei fuse with additional helium to produce a stable isotope of oxygen and energy: 12 6 C + 4 2 He → 16 8 O + γ (+7.162 MeV) Nuclear fusion reactions of helium with hydrogen produces lithium-5, which also is highly unstable, and decays back into smaller nuclei with a half-life of 3.7 × 10 −22 s.
Once the helium-3 has been produced, there are four possible paths to generate 4 He. In p–p I, helium-4 is produced by fusing two helium-3 nuclei; the p–p II and p–p III branches fuse 3 He with pre-existing 4 He to form beryllium-7, which undergoes further reactions to produce two helium-4 nuclei. About 99% of the energy output of the sun ...
Supernova nucleosynthesis is the nucleosynthesis of chemical elements in supernova explosions.. In sufficiently massive stars, the nucleosynthesis by fusion of lighter elements into heavier ones occurs during sequential hydrostatic burning processes called helium burning, carbon burning, oxygen burning, and silicon burning, in which the byproducts of one nuclear fuel become, after ...
Today, nucleosynthesis is widely considered to have taken place in two stages: formation of hydrogen and helium according to the Alpher–Bethe–Gamow theory, and stellar nucleosynthesis of higher elements according to Bethe and Hoyle's later theories.
Illustration of a proton–proton chain, from hydrogen forming deuterium, helium-3, and regular helium-4. Nuclear transmutation is the conversion of one chemical element or an isotope into another chemical element. [1] Nuclear transmutation occurs in any process where the number of protons or neutrons in the nucleus of an atom is changed.