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Nucleosynthesis is the process that creates new atomic nuclei from pre-existing nucleons (protons and neutrons) and nuclei. According to current theories, the first nuclei were formed a few minutes after the Big Bang , through nuclear reactions in a process called Big Bang nucleosynthesis . [ 1 ]
The term p-process (p for proton) is used in two ways in the scientific literature concerning the astrophysical origin of the elements (nucleosynthesis).Originally it referred to a proton capture process which was proposed to be the source of certain, naturally occurring, neutron-deficient isotopes of the elements from selenium to mercury.
A version of the periodic table indicating the origins – including big bang nucleosynthesis – of the elements. All elements above 103 are also man-made and are not included. Big Bang nucleosynthesis produced very few nuclei of elements heavier than lithium due to a bottleneck: the absence of a stable nucleus with 8 or 5 nucleons. This ...
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.
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.
Neutron capture nucleosynthesis describes two nucleosynthesis pathways: the r-process and the s-process, for rapid and slow neutron captures, respectively. R-process describes neutron capture in a region of high neutron flux , such as during supernova nucleosynthesis after core-collapse, and yields neutron-rich nuclides .
The x-process in cosmic rays is the primary means of nucleosynthesis for the five stable isotopes of lithium, beryllium, and boron. [2] As the proton–proton chain reaction cannot proceed beyond 4 He due to the unbound nature of 5 He and 5 Li, [ 3 ] and the triple-alpha process skips over all species between 4 He and 12 C, these elements are ...
While the drip lines impose the ultimate boundaries for nucleosynthesis, in high-energy environments the burning pathway may be limited before the drip lines are reached by photodisintegration, where a high-energy gamma ray knocks a nucleon out of a nucleus. The same nucleus is subject both to a flux of nucleons and photons, so an equilibrium ...