Nucleosynthesis theory

Stellar fusion or nucleosynthesis occurs in

Once these clouds became large enough, they were drawn together by gravity with enough force to actually cause the atomic nuclei to fuse, in a process called nuclear fusion. Stars like the sun Details were discussed in the section on Fusion. Before one neutron half-life passed nearly every neutron had paired up with a proton, and nearly every one of these pairs had paired up to form helium. Elements heavier than iron may be made in neutron star mergers or supernovae after the r-process. Burbidge, M. Furthermore, one value of this baryon density can explain all the abundances at once. A similar enigma exists for the deuterium. In astronomy — and astrophysics and cosmology — there are two main kinds of nucleosynthesis, Big Bang nucleosynthesis BBN , and stellar nucleosynthesis. In this way, the alpha process preferentially produces elements with even numbers of protons by the capture of helium nuclei.

And one more: in a supernova, especially a core collapse supernova, huge quantities of new nuclei are synthesized, very quickly, in the nuclear reactions triggered by the flood of neutrons. While this theory achieved relative success, it was discovered to be lacking in some important respects.

nucleosynthesis equations

Gradually it became clear that hydrogen and helium are much more abundant than any of the other elements. As a main sequence star ages, the core temperature will rise, resulting in a steadily increasing contribution from its CNO cycle.

In the cores of lower-mass main-sequence stars such as the Sunthe dominant energy production process is the proton—proton chain reaction.

supernova nucleosynthesis

To do that you need stars, which means waiting around for at least billion years. This alternative theory was called a steady state theory and fell out of favor when the cosmic microwave background radiation was detected.

explosive nucleosynthesis

In the 's and 60's the predominant theory regarding the formation of the chemical elements in the Universe was due to the work of G.

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Big Bang nucleosynthesis