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Abundance peaks for the r-process occur near mass numbers A = 82 (elements Se, Br, and Kr), A = 130 (elements Te, I, and Xe) and A = 196 (elements Os, Ir, and Pt). The r -process entails a succession of rapid neutron captures (hence the name) by one or more heavy seed nuclei , typically beginning with nuclei in the abundance peak centered on 56 ...
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 ...
Stars fuse light elements to heavier ones in their cores, giving off energy in the process known as stellar nucleosynthesis. Nuclear fusion reactions create many of the lighter elements, up to and including iron and nickel in the most massive stars. Products of stellar nucleosynthesis remain trapped in stellar cores and remnants except if ...
The need for a physical description was already inspired by the relative abundances of the chemical elements in the solar system. Those abundances, when plotted on a graph as a function of the atomic number of the element, have a jagged sawtooth shape that varies by factors of tens of millions (see history of nucleosynthesis theory). [4]
The kilonova briefly mimicked the conditions immediately following the Big Bang, and allowed scientists to confirm the source of the heavy elements Strontium and Yttrium for the very first time.
The stable alpha elements are: C, O, Ne, Mg, Si, and S. The elements Ar and Ca are "observationally stable". They are synthesized by alpha capture prior to the silicon fusing stage, that leads to Type II supernovae. Si and Ca are purely alpha process elements. Mg can be separately consumed by proton capture reactions.
The four most tightly bound nuclei, in decreasing order of binding energy per nucleon, are 62 Ni, 58 Fe, 56 Fe, and 60 Ni. [22] Even though the nickel isotope, 62 Ni, is more stable, the iron isotope 56 Fe is an order of magnitude more common. This is due to the fact that there is no easy way for stars to create 62 Ni through the alpha process.
The key parameter which allows one to calculate the effects of Big Bang nucleosynthesis is the baryon/photon number ratio, which is a small number of order 6 × 10 −10. This parameter corresponds to the baryon density and controls the rate at which nucleons collide and react; from this it is possible to calculate element abundances after ...