Nucleosynthesis is the process of creating new atomic nuclei from preexisting nucleons (protons and neutrons). The primordial preexisting nucleons were formed from the quark-gluon plasma of the Big Bang as it cooled below ten million degrees. This first process may be called nucleogenesis, the genesis of nucleons in the universe. The subsequent nucleosynthesis of the elements (including all carbon, all oxygen, etc.) occurs primarily in stars either by nuclear fusion or nuclear fission. The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... Overveiw of the proton-proton chain. ... This article does not cite its references or sources. ... The triple alpha process is the process by which three helium nuclei (alpha particles) are transformed into carbon. ... The carbon burning process is a nuclear fusion reaction that occurs in massive stars (at least 4 MSun at birth) that have used up the lighter elements in their cores. ... Neon burning process is a set of nuclear fusion reactions that take place in massive stars (at least 8 MSun). ... The oxygen burning process is a nuclear fusion reaction that occurs in massive stars that have used up the lighter elements in their cores. ... In astrophysics, silicon burning is a nuclear fusion reaction which occurs in massive stars. ... The process of neutron capture can proceed in two ways - as a rapid process (an r-process) or a slow process (an s-process). ... The R process (R for rapid) is a neutron capture process for radioactive elements which occurs in high neutron density, high temperature conditions. ... The S process (S for slow) is a neutron capture process in the decay of radioactive elements that occurs in lower neutron density, lower temperature conditions. ... The p process was believed to be a proton capture process which occurrs during supernovae explosions. ... The rp process (rapid proton capture process) consists of consecutive proton captures onto seed nuclei to produce heavier elements. ... In nuclear physics, spallation is the process in which a heavy nucleus emits a large number of nucleons as a result of being hit by a high-energy proton, thus greatly reducing its atomic weight. ... A Plasma lamp, illustrating some of the more complex phenomena of a plasma, including filamentation A solar coronal mass ejection blasts plasma throughout the solar system. ... According to the Big Bang, the universe emerged from an extremely dense and hot state (bottom). ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Atomic mass 12. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... The Pleiades, an open cluster of stars in the constellation of Taurus. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... For the generation of electrical power by fission, see Nuclear power plant An induced nuclear fission event. ...

History

The first ideas were that the chemical elements were created at the beginnings of the universe, but no successful picture could be found. Arthur Stanley Eddington first suggested in 1920 that stars obtain their energy by fusing hydrogen to helium, but this idea was not generally accepted because it lacked nuclear mechanisms. Hans Bethe first provided those nuclear mechanisms by which hydrogen is fused into helium in the years immediately before World War II. But neither of these early works on stellar power addressed the origin of the elements heavier than helium. Fred Hoyle's original work on nucleosynthesis of heavier elements in stars occurred just after World War II. This work attributed production of heavier elements from hydrogen in stars during the nuclear evolution of their compositions. Subsequently, Hoyle's picture was expanded during the 1960s by creative contributions by William A. Fowler, Alistair G. W. Cameron, and Donald D. Clayton, and then by many others. One of Sir Arthur Stanley Eddingtons papers announced Einsteins theory of general relativity to the English-speaking world. ... Hans Albrecht Bethe (pronounced bay-tuh; July 2, 1906 – March 6, 2005), was a German-American physicist who won the Nobel Prize in Physics in 1967 for his work on the theory of stellar nucleosynthesis. ... Sir Fred Hoyle Sir Fred Hoyle (June 24, 1915 in Bingley, Yorkshire – August 20, 2001 in Bournemouth, England) was a British astronomer, notable for a number of his theories that run counter to current astronomical opinion, and a writer of science fiction, including a number of books co-authored by... There is another William Fowler who was a Scottish poet and uncle of William Drummond of Hawthornden William Alfred Willy Fowler (August 9, 1911 – March 14, 1995) was an American astrophysicist. ...

Processes

There are a number of astrophysical processes which are believed to be responsible for nucleosynthesis in the universe. The majority of these occur within the hot matter inside stars. The successive nuclear fusion processes which occur inside stars are known as hydrogen burning(via the proton-proton chain or the CNO cycle), helium burning, carbon burning, neon burning, oxygen burning and silicon burning. These processes are able to create elements up to iron and nickel, the region of the isotopes having the highest binding energy per nucleon. Heavier elements can be assembled within stars by a neutron capture process known as the s process or in explosive environments, such as supernovae, by a number of processes. Some of the more important of these include the r process which involves rapid neutron captures, the rp process which involves rapid proton captures and the p process (sometimes known as the gamma process) which involves photodisintegration of existing nuclei. Spiral Galaxy ESO 269-57 Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties (luminosity, density, temperature and chemical composition) of astronomical objects such as stars, galaxies, and the interstellar medium, as well as their interactions. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... The proton-proton chain reaction is one of two fusion reactions by which stars convert hydrogen to helium, the other being the CNO cycle. ... This article does not cite its references or sources. ... Helium fusion is a kind of nuclear fusion, with the nuclei involved being helium. ... The carbon burning process is a nuclear fusion reaction that occurs in massive stars (at least 4 MSun at birth) that have used up the lighter elements in their cores. ... Neon burning process is a set of nuclear fusion reactions that take place in massive stars (at least 8 MSun). ... The oxygen burning process is a nuclear fusion reaction that occurs in massive stars that have used up the lighter elements in their cores. ... In astrophysics, silicon burning is a nuclear fusion reaction which occurs in massive stars. ... Binding energy is the energy required to disassemble a whole into separate parts. ... The S process (S for slow) is a neutron capture process in the decay of radioactive elements that occurs in lower neutron density, lower temperature conditions. ... Multiwavelength X-ray image of the remnant of Keplers Supernova, SN 1604. ... The R process (R for rapid) is a neutron capture process for radioactive elements which occurs in high neutron density, high temperature conditions. ... The rp process (rapid proton capture process) consists of consecutive proton captures onto seed nuclei to produce heavier elements. ... The p process was believed to be a proton capture process which occurrs during supernovae explosions. ...

Types of nucleosynthesis

Four types of nucleosynthesis are known.

Big Bang nucleosynthesis

Big Bang nucleosynthesis occurred within the first three minutes of the universe and is responsible for much of the abundance ratios of ¹H (protium), ²H (deuterium), helium-3 (³He), and helium-4 (⁴He), in the universe [1]. Although ⁴He continues to be produced by other mechanisms (such as stellar fusion and alpha decay) and trace amounts of ¹H continue to be produced by spallation and certain types of radioactive decay (proton emission and neutron decay), most of the mass of these isotopes in the universe, and all but the insignificant traces of the ³He and deuterium in the universe produced by rare processes such as cluster decay, are thought to have been produced in the Big Bang. The nuclei of these elements, along with some ⁷Li, are believed to have been formed when the universe was between 100 and 300 seconds old, after the primordial quark-gluon plasma froze out to form protons and neutrons. Because of the very short period in which Big Bang nucleosynthesis occurred before being stopped by expansion and cooling, no elements heavier than lithium could be formed. (Elements formed during this time were in the plasma state, and did not cool to the state of neutral atoms until much later). In cosmology, Big Bang nucleosynthesis (or primordial nucleosynthesis) refers to the production of nuclei other than H-1, the normal, light hydrogen, during the early phases of the universe, shortly after the Big Bang. ... Protium can be several things: In chemistry, protium is the most common isotope of the element hydrogen; that has one proton and no neutrons. ... Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of planet Earth of approximately one atom in 6500 of hydrogen (~154 PPM). ... Proton emission (also known as proton radioactivity) is a type of radioactive decay in which a proton is ejected from a nucleus. ... The term neutron decay can have several meanings in nuclear physics: Beta decay, a process whereby a neutron decays into a proton, an electron and an anti-neutrino. ... Cluster decay is the nuclear process in which a radioactive atom emits a cluster of neutrons and protons. ... According to the Big Bang, the universe emerged from an extremely dense and hot state (bottom). ... These are the 6 quarks and their most likely decay modes. ... In particle physics, gluons are vector gauge bosons that mediate strong color charge interactions of quarks in quantum chromodynamics (QCD). ... // For alternative meanings see proton (disambiguation). ... This article or section does not cite its references or sources. ... General Name, Symbol, Number lithium, Li, 3 Chemical series alkali metals Group, Period, Block 1, 2, s Appearance silvery white/grey Atomic mass 6. ...

Stellar nucleosynthesis

Stellar nucleosynthesis occurs in stars during the process of stellar evolution. It is responsible for generation of elements from carbon to calcium by nuclear fusion processes. Stars are the nuclear furnaces in which H and He are fused into heavier nuclei. Of particular importance is carbon, because its formation from He is a bottleneck in the entire process. Carbon is also the main element used in the production of free neutrons within the stars, giving rise to the s process which involves the slow absorption of neutrons to produce elements heavier than iron and nickel (⁵⁷Fe and ⁶²Ni). Carbon and other elements formed by this process are also fundamental to life. The products of stellar nucleosynthesis are generally distributed into the universe as planetary nebulae or through the solar wind. The first direct proof that nucleosynthesis occurs stars was the detection of technetium in the atmosphere of a red giant in the early 1950s^[1] Many modern proofs appear in the isotopic composition of Stardust, solid grains from individual stars which have been extracted from meteorites. Stardust is one component of cosmic dust. The measured isotopic compositions demonstrate many aspects of nucleosynthesis within the stars from which the Stardust grains condensed ^[2] Cross section of a red giant showing nucleosynthesis and elements formed Stellar nucleosynthesis is the collective term for the nuclear reactions taking place in stars to build the nuclei of the heavier elements. ... In astronomy, stellar evolution is the sequence of changes that a star undergoes during its lifetime; the hundreds of thousands, millions or billions of years during which it emits light and heat. ... General Name, Symbol, Number carbon, C, 6 Chemical series nonmetals Group, Period, Block 14, 2, p Appearance black (graphite) colorless (diamond) Atomic mass 12. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... The S process (S for slow) is a neutron capture process in the decay of radioactive elements that occurs in lower neutron density, lower temperature conditions. ... Biology (from Greek βίος λόγος, see below) is the study of life. ... NGC 6543, the Cats Eye Nebula A planetary nebula is an astronomical object consisting of a glowing shell of gas and plasma formed by certain types of stars at the end of their lives. ... The plasma in the solar wind meeting the heliopause For the British comic, see Solar Wind (comic). ... General Name, Symbol, Number technetium, Tc, 43 Chemical series transition metals Group, Period, Block 7, 5, d Appearance silvery gray metal Atomic mass [98](0) g/mol Electron configuration [Kr] 4d5 5s2 Electrons per shell 2, 8, 18, 13, 2 Physical properties Phase solid Density (near r. ... Artists conception of the remains of artificial structures on the Earth after the Sun enters its red giant phase and swells to roughly 100 times its current size. ... This article describes dust in the astronomical cosmic context, of which interplanetary dust and interstellar dust are particular types. ...

Explosive nucleosynthesis

This includes supernova nucleosynthesis, and produces the elements heavier than iron by an intense burst of nuclear reactions that typically last but seconds during the explosion of the supernova core. In explosive environments of supernovae, the elements between silicon and nickel are synthesized by fast fusion. Also in supernovae further nucleosynthesis processes can occur, such as the r process (in which the most neutron-rch isotopes of elements heavier than nickel are produced by rapid absorption of free neutrons)released during the explosions. It is responsible for our natural cohort of radioactive elements, such as uranium and thorium. The rp process involves the rapid absorption of free protons as well as neutrons, but its role is less certain. The most convincing proof of explosive nucleosynthesis in supernovae occurred when gamma-ray lines were detected emerging from supernova 1987A. Gamma ray lines from ⁵⁶Co and ⁵⁷Co , whose radioactive halflives limit their age to about a year, proved that ⁵⁶Fe and ⁵⁷Fe were created by radioactive parents. This nuclear astronomy was predicted by Donald D. Clayton and colleagues in 1969, which played an important role in the planning for NASA's successful Compton Gamma-Ray Observatory. Other proofs of explosive nucleosynthesis are found within the Stardust grains that condensed within the intetriors of supernova as they expanded and cooled. Stardust grains are one component of cosmic dust. In particular, radioactive ⁴⁴Ti was measured to be very abundant within supernova Stardust grains at the time they condensed during the supernova expansion, confirming a 1975 prediction for identifying supernova Stardust (see Ref 2). Other unusual isotopic ratios within those grains show other aspects of explosive nucleosynthesis. Composite image of Keplers supernova from pictures by the Spitzer Space Telescope, Hubble Space Telescope, and Chandra X-ray Observatory. ... Multiwavelength X-ray image of the remnant of Keplers Supernova, SN 1604. ... The R process (R for rapid) is a neutron capture process for radioactive elements which occurs in high neutron density, high temperature conditions. ... This article or section does not cite its references or sources. ... The rp process (rapid proton capture process) consists of consecutive proton captures onto seed nuclei to produce heavier elements. ... // For alternative meanings see proton (disambiguation). ... This article describes dust in the astronomical cosmic context, of which interplanetary dust and interstellar dust are particular types. ...

Cosmic ray spallation

Cosmic ray spallation produces some of the lightest elements present in the universe (though not significant deuterium). Most notably spallation is believed to be responsible for the generation of all or almost all of ³He and the elements lithium, beryllium and boron. This process results from the impact of cosmic rays against the interstellar medium, fragmenting carbon, nitrogen and oxygen nuclei present in the cosmic rays. Note that Be and B are not significantly produced in stellar fusion processes, because the instability of any ⁸Be formed from two ⁴He nuclei prevents simple 2-particle reaction building-up of these elements. Cosmic ray spallation is a form of naturally occuring nuclear fission and nucleosynthesis. ... Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of planet Earth of approximately one atom in 6500 of hydrogen (~154 PPM). ... General Name, Symbol, Number lithium, Li, 3 Chemical series alkali metals Group, Period, Block 1, 2, s Appearance silvery white/grey Atomic mass 6. ... General Name, Symbol, Number beryllium, Be, 4 Chemical series alkaline earth metals Group, Period, Block 2, 2, s Appearance white-gray metallic Atomic mass 9. ... General Name, Symbol, Number boron, B, 5 Chemical series metalloids Group, Period, Block 13, 2, p Appearance black/brown Atomic mass 10. ... Cosmic rays can loosely be defined as energetic particles originating outside of the Earth. ... The distribution of ionized hydrogen (known by astronomers as H II (aitch two) from old spectroscopic terminology) in the parts of the Galactic interstellar medium visible from the Earths northern hemisphere (from the Wisconsin H-Alpha Mapper Survey) In astronomy, the interstellar medium (or ISM) is the matter (interstellar...

Theories of nucleosynthesis are tested by calculating isotope abundances and comparing with observed results. Isotope abundances are typically calculated by calculating the transition rates between isotopes in a network. Often these calculations can be simplified as a few key reactions control the rate of other reactions. Isotopes are any of the several different forms of an element each having different atomic mass. ...

See also

• Stellar evolution
• cosmic dust

In astronomy, stellar evolution is the sequence of changes that a star undergoes during its lifetime; the hundreds of thousands, millions or billions of years during which it emits light and heat. ... This article describes dust in the astronomical cosmic context, of which interplanetary dust and interstellar dust are particular types. ...

References

1. ^ S. Paul W. Merrill (1952). "Spectroscopic Observations of Stars of Class". THE ASTROPHYSICAL JOURNAL 116: 21.
2. ^ D. D. Clayton and L. R. Nittler (2004). "Astrophysics with Presolar Stardust". ANNUAL REVIEW OF ASTRONOMY AND ASTROPHYSICS 42: 39-78.

• E. M. Burbidge, G. R. Burbidge, W. A. Fowler, F. Hoyle, Synthesis of the Elements in Stars, Rev. Mod. Phys. 29 (1957) 547 (article at the Physical Review Online Archive (subscription required)).
• D. D. Clayton, "Principles of Stellar Evolution and Nucleosynthesis", McGraw-Hill, 1968; University of Chicago Press, 1983, ISBN 0-226-10952-6
• C. E. Rolfs, W. S. Rodney, Cauldrons in the Cosmos, Univ. of Chicago Press, 1988, ISBN 0-226-72457-3.
• D. D. Clayton, "Handbook of Isotopes in the Cosmos", Cambridge University Press, 2003, ISBN 0 521 823811.