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In astrophysics, stellar nucleosynthesis is the creation of chemical elements by nuclear fusion reactions within stars. Stellar nucleosynthesis has occurred since the original creation of hydrogen, helium and lithium during the Big Bang. As a predictive theory, it yields accurate estimates of the observed abundances of the elements.
The supernova shock wave produced by stellar collapse provides ideal conditions for these processes to briefly occur. During this terminal heating involving photodisintegration and rearrangement, nuclear particles are converted to their most stable forms during the supernova and subsequent ejection through, in part, alpha processes.
The s-process is believed to occur mostly in asymptotic giant branch stars, seeded by iron nuclei left by a supernova during a previous generation of stars. In contrast to the r-process which is believed to occur over time scales of seconds in explosive environments, the s-process is believed to occur over time scales of thousands of years, passing decades between neutron captures.
The B 2 FH paper was ostensibly a review article summarising recent advances in the theory of stellar nucleosynthesis. [8] However, it went beyond simply reviewing Hoyle's work, by incorporating observational measurements of elemental abundances published by the Burbidges, and Fowler's laboratory experiments on nuclear reactions.
Nucleogenesis (also known as nucleosynthesis) as a general phenomenon is a process usually associated with production of nuclides in the Big Bang or in stars, by nuclear reactions there. Some of these neutron reactions (such as the r-process and s-process ) involve absorption by atomic nuclei of high-temperature (high energy) neutrons from the ...
The x-process in cosmic rays is the primary means of nucleosynthesis for the five stable isotopes of lithium, beryllium, and boron. [3] As the proton–proton chain reaction cannot proceed beyond 4 He due to the unbound nature of 5 He and 5 Li, [ 4 ] and the triple-alpha process skips over all species between 4 He and 12 C, these elements are ...
Fusing with additional helium nuclei can create heavier elements in a chain of stellar nucleosynthesis known as the alpha process, but these reactions are only significant at higher temperatures and pressures than in cores undergoing the triple-alpha process.
The study of presolar grains provides information about nucleosynthesis and stellar evolution. [3] Grains bearing the isotopic signature of "r-process" (rapid neutron capture) and alpha process (alpha capture) types of nucleosynthesis are useful in testing models of supernova explosions. [30]