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Encyclopedia > Stellar nucleosynthesis
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Cross section of a red giant showing nucleosynthesis and elements formed
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. (For other such processes, see nucleosynthesis.) Jump to: navigation, search Image File history File links Nucleosynthesis_in_a_star. ... Jump to: navigation, search Image File history File links Nucleosynthesis_in_a_star. ... Jump to: navigation, search According to the Hertzsprung-Russell diagram, a red giant is a large non-main sequence star of stellar classification K or M; so-named because of the reddish appearance of the cooler giant stars. ... A stylized representation of a lithium atom. ... Jump to: navigation, search The Pleiades star cluster A star is a massive body of plasma in outer space that is currently producing or has produced energy through nuclear fusion. ... Jump to: navigation, search A chemical element, often called simply element, is the class of atoms which contain the same number of protons. ... Nucleosynthesis is the process of creating new atomic nuclei either by nuclear fusion or nuclear fission. ...


The processes involved began to be understood early in the 20th century, when it was first realised that the energy released from nuclear reactions accounted for the longevity of the Sun as a source of heat and light. The prime energy producer in the sun is the fusion of hydrogen to helium, which occurs at a minimum temperature of 3 million kelvins. (19th century - 20th century - 21st century - more centuries) Decades: 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s As a means of recording the passage of time, the 20th century was that century which lasted from 1901–2000 in the sense of the Gregorian calendar (1900–1999 in the... Jump to: navigation, search The Sun is the star at the centre of our Solar system. ... Jump to: navigation, search A red-hot iron rod cooling after being worked by a blacksmith. ... Jump to: navigation, search Prism splitting light Light is electromagnetic radiation with a wavelength that is visible to the eye (visible light) or, in a technical or scientific setting, electromagnetic radiation of any wavelength. ... Fusion typically refers to the merging of two or more entities into a single one: In physics, nuclear fusion is the combination of two atomic nuclei into a single nucleus. ... Jump to: navigation, search General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Jump to: navigation, search General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... Jump to: navigation, search The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. ...

Contents


History

Nucleosynthesis
Related topics

edit Nucleosynthesis is the process of creating new atomic nuclei either by nuclear fusion or nuclear fission. ... Image File history File links File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... In cosmology, Big Bang nucleosynthesis (alternately: 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. ... Composite image of Keplers supernova from pictures by the Spitzer Space Telescope, Hubble Space Telescope, and Chandra X-ray Observatory. ... Cosmic ray spallation is a form of naturally occuring nuclear fission and nucleosynthesis. ... 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. ... Jump to: navigation, search The deuterium-tritium fusion reaction is considered the most promising for producing fusion power. ... 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. ... Jump to: navigation, search Sketch of induced nuclear fission, a neutron (n) strikes a uranium nucleus which splits into similar products (F. P.), and releases more neutrons to continue the process, and energy in the form of gamma and other radiation. ...

In 1920, Arthur Eddington, on the basis of the precise measurements of atoms by F.W. Aston, was the first to suggest that stars obtained their energy from nuclear fusion of hydrogen to form helium. In 1928, George Gamow derived what is now called the Gamow factor, a quantum-mechanical formula that gave the probability of bringing two nuclei sufficiently close for the strong nuclear force to overcome the Coulomb barrier. The Gamow factor was used in the decade that followed by Atkinson and Houtermans and later by Gamow himself and Teller to derive the rate at which nuclear reactions would proceed at the high temperatures believed to exist in stellar interiors. Jump to: navigation, search 1920 is a leap year starting on Thursday (link will take you to calendar) // Events WIKIPEDIA EATS VAGINA January 7 - Forces of Russian White admiral Kolchak surrender in Krasnoyarsk. ... One of Sir Arthur Stanley Eddingtons papers announced Einsteins theory of general relativity to the English-speaking world. ... Francis William Aston (born Birmingham, September 1, 1877; died Cambridge, November 20, 1945) was a British physicist who won the 1922 Nobel Prize in Chemistry for the invention of the mass spectrometer. ... Jump to: navigation, search The deuterium-tritium fusion reaction is considered the most promising for producing fusion power. ... Jump to: navigation, search General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Jump to: navigation, search General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... Jump to: navigation, search 1928 was a leap year starting on Sunday (link will take you to calendar). ... George Gamow (pronounced GAM-off) (March 4, 1904 – August 19, 1968) , born Georgiy Antonovich Gamow (Георгий Антонович Гамов) was a Ukrainian born physicist and cosmologist. ... Jump to: navigation, search Fig. ... The strong nuclear force or strong interaction (also called color force or colour force) is a fundamental force of nature which affects only quarks and antiquarks, and is mediated by gluons in a similar fashion to how the electromagnetic force is mediated by photons. ... The Coulomb barrier, named after physicist Charles-Augustin de Coulomb (1736—1806), is the energy barrier due to electrostatic interaction that two nuclei need to overcome so they can get close enough to undergo nuclear fusion. ... Robert Atkinson is the name of several people, including: Robert Chatham Atkinson, U.S. administrator. ... Friedrich Georg Houtermans (January 22, 1903 - March 1, 1966) was a physicist born in Zoppod near Danzig (today Gdansk, Poland). ... Edward Teller in 1958 as Director of Lawrence Livermore National Laboratory. ...


In 1939, in a paper entitled "Energy Production in Stars", Hans Bethe analyzed the different possibilities for reactions by which hydrogen is fused into helium. He selected two processes that he believed to be the sources of energy in stars. The first one, the proton-proton chain, is the dominant energy source in stars with masses up to about the mass of the Sun. The second process, the carbon-nitrogen-oxygen cycle, which was also considered by Carl Friedrich von Weizs├Ącker in 1938, is most important in more massive stars. Jump to: navigation, search 1939 was a common year starting on Sunday (link will take you to calendar). ... Hans Bethe Hans Albrecht Bethe (pronounced Bay-tuh; July 2, 1906 – March 6, 2005), was a German-American physicist who won the Nobel Prize in Physics for 1967 for his discovery of stellar nucleosynthesis. ... The proton-proton chain reaction is one of two fusion reactions by which stars convert hydrogen to helium, the other being the CNO cycle. ... The CNO (carbon-nitrogen-oxygen) cycle is one of two fusion reactions by which stars convert hydrogen to helium, the other being the proton-proton chain. ... Carl Friedrich von Weizsäcker (born 28 June 1912) is a German physicist. ... Jump to: navigation, search 1938 was a common year starting on Saturday (link will take you to calendar). ...


Later, many important details were added to Bethe's theory, like the publication of a celebrated paper in 1957 by Burbidge, Burbidge, Fowler and Hoyle. This latter work collected and refined earlier researches into a coherent picture that accounted for the observed relative abundances of the elements. Jump to: navigation, search 1957 was a common year starting on Tuesday of the Gregorian calendar. ... Margaret Burbidge (nee Eleanor Margaret Peachey) (born August 12, 1919) is a British astrophysicist, noted for original research and holding many administrative posts, including director of the Royal Greenwich Observatory. ... Geoffrey Ronald Burbidge (September 24, 1925 – ) is a British-American physics professor in the University of California. ... 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. ... Sir Fred Hoyle Sir Fred Hoyle (June 24, 1915 in Yorkshire – August 20in Bournemouth, England, 2001) 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 his son...


Key Reactions

The most important reactions in stellar nucleosynthesis are:

Jump to: navigation, search General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... The proton-proton chain reaction is one of two fusion reactions by which stars convert hydrogen to helium, the other being the CNO cycle. ... The CNO (carbon-nitrogen-oxygen) cycle is one of two fusion reactions by which stars convert hydrogen to helium, the other being the proton-proton chain. ... Jump to: navigation, search General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... Jump to: navigation, search The triple alpha process is the process by which three helium nuclei (alpha particles) are transformed into carbon. ... The alpha reactions is one of two class of fusion reactions by which stars convert helium into heavier elements, the other being the triple_alpha process. ... 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. ... Jump to: navigation, search General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... 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. ...

References

  • H. A. Bethe, Energy Production in Stars, Phys. Rev. 55 (1939) 103; online edition (subscription needed)
  • H. A. Bethe, Energy Production in Stars, Phys. Rev. 55 (1939) 434-456; online edition (subscription needed)
  • Alak K. Ray (2004) Stars as thermonuclear reactors: their fuels and ashes (arxiv.org article)

External links

  • How the Sun Shines by John N. Bacall
  • http://helios.gsfc.nasa.gov/nucleo.html

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