Supernova nucleosynthesis

Explain how new chemical elements are generated in supernovae

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Supernova nucleosynthesis Is to clarify how new chemical elements Supernova Generated internally, mainly in explosive Oxygen combustion and Silicon combustion From the explosion process of Nucleosynthesis 。 The elements created by these fusion reactions are silicon 、 sulfur 、 chlorine 、 argon 、 potassium 、 calcium 、 scandium 、 titanium and Tiefeng Peak Element: vanadium 、 chromium 、 manganese 、 iron 、 cobalt 、 nickel 。 Because these elements are thrown out in each supernova explosion, their abundance in the interstellar medium is increasing. Heavy elements (heavier than nickel) are mainly composed of r-process capture neutron Created. However, there are other processes for certain elements Nucleosynthesis Contribute, like the famous capture proton Of Rp Process And cause Photoinduced metamorphosis Procedural Gamma process or P-process 。 The lightest and least neutron isotopes of heavy elements are produced by the latter's procedure.

Chinese name: Supernova nucleosynthesis

Foreign name: Supernova nucleosynthesis

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Supernova nucleosynthesis Is to clarify the new chemical element How to Supernova Generated internally, mainly in explosive Oxygen combustion and Silicon combustion From the explosion process of Nucleosynthesis 。 The elements created by these fusion reactions are silicon 、 sulfur 、 chlorine 、 argon 、 potassium 、 calcium 、 scandium 、 titanium and Tiefeng Peak Element: vanadium 、 chromium 、 manganese 、 iron 、 cobalt 、 nickel 。 Because these elements are thrown out in each supernova explosion, their abundance in the interstellar medium is increasing. Heavy elements (heavier than nickel) are mainly composed of r-process capture neutron Created. However, there are other processes for certain elements Nucleosynthesis Contribute, like the famous capture proton Of Rp Process And cause Photoinduced metamorphosis Procedural Gamma process or P-process 。 The lightest and least neutron isotopes of heavy elements are produced by the latter's procedure.^[1]

Supernova

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Main entry: Supernova

Supernova is the phenomenon of violent explosion of stars, which mainly occurs in the following two ways. The first is White dwarf By absorption companion (usually Red Giant ）The quality of Chandraseka limit After that, the core based explosion was carried out. The second, which is also common, is caused by massive stars, usually Red Giant , reaching the nuclear fusion (or combustion) process of iron. Because iron is one of the elements Binding energy One of the highest and the last element that can release heat energy produced by nuclear fusion. Since then, all nuclear fusion reactions have begun endothermic The star loses energy, so the gravity of the star quickly sucks in several layers outside, the star collapses quickly, and then forms a supernova explosion.^[1]

Fusion of elements

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Because the supernova explosion releases a huge amount of energy, it also produces a higher temperature than the star can produce. The environment created by such high temperature makes Atomic weight Up to 254 elements can also be formed, Californium Is the heaviest element known, but in earth Only manual synthesis 。 stay nuclear fusion In the process of, Stellar nucleosynthesis The heaviest element that can be fused is nickel The atomic weight of the isotope can reach 56. Only those stars with the largest mass can produce elements with atomic sequence between silicon and nickel, and end the life of stars with supernova explosion (see Silicon combustion ）。 go by the name of S-process The neutron capture process of Stellar nucleosynthesis The heaviest isotope can be produced at the stage of bismuth , but S-Process It is mainly carried out at a very slow speed in low mass stars.^[1]

R-Process

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Main entry: r-process

When supernova nucleosynthesis occurs, r-process (r means fast) Create many heavy isotopes rich in neutrons, which will decay into stable isotopes first, thus creating all heavy elements rich in neutrons stable isotope 。 These neutron trapping processes occur in the environment of high neutron density and high temperature. In the r-process, any one of them suffers from high neutron density flow Heavy set Nucleus Will form extremely unstable and neutron rich nucleus And quickly passed through Beta decay become Atomic order Higher, but Atomic weight The same and more stable atom. The density of neutron flow is extremely high, about 10 neutrons per square centimeter per second. The first dynamic r-process calculated shows that the evolution changes with time, and it is also considered that the abundance of the r-process is the superposition of different neutron fluxes. The low flux r-process produces the first abundance peak of non radioactive elements near the atomic weight A=130; The high flux element produces radioactive uranium and thorium, and there is no peak of A=130. According to the details, these processes can be completed in a flash to a few seconds. Then hundreds of papers used this time related approximation method. Interestingly, the only supernova nearby in modern times, SN 1987A , does not show the richness of the r-process. The current thinking is that some products of the r-process are not thrown out of the supernova, but are swallowed up as part of the wreckage of the neutron star or black hole.^[1]

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