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Encyclopedia > Supernova nucleosynthesis
Nucleosynthesis
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edit Nucleosynthesis is the process of creating new atomic nuclei from preexisting nucleons (protons and neutrons). ... Image File history File links Wpdms_physics_proton_proton_chain_1. ... 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 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. ... 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 celestial 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 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. ... For the generation of electrical power by fission, see Nuclear power plant An induced nuclear fission event. ...

Supernova nucleosynthesis refers to the production of new chemical elements inside supernovae. It occurs primarily due to explosive nucleosynthesis during explosive oxygen burning and silicon burning [1]. Those fusion reactions create the elements silicon, sulfur, chlorine, argon, potassium, calcium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt and nickel. As a result of their ejection from individual supernovae, their abundances grow increasingly larger within the interstellar medium. Heavy elements (heavier than nickel) are created primarily by a neutron capture process known as the r process. However, there are other processes thought to be responsible for some of the element nucleosynthesis, notably a proton capture process known as the rp process and a photodisintegration process known as the gamma (or p) process. The latter synthesizes the lightest, most neutron-poor, isotopes of the heavy elements. The periodic table of the chemical elements (this version outdated on October 13, 2006) A chemical element, or element for short, is a pure substance that cannot be decomposed into any simpler substance. ... Multiwavelength X-ray image of the remnant of Keplers Supernova, SN 1604. ... Nucleosynthesis is the process of creating new atomic nuclei from preexisting nucleons (protons and neutrons). ... ≈≈ This article or section does not cite its references or sources. ... The R process (R for rapid) is a neutron capture process for radioactive elements which occurs in high neutron density, high temperature conditions. ... Nucleosynthesis is the process of creating new atomic nuclei from preexisting nucleons (protons and neutrons). ... // For alternative meanings see proton (disambiguation). ... 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. ...

Contents

Supernovae

Main Article: Supernova. Multiwavelength X-ray image of the remnant of Keplers Supernova, SN 1604. ...


A supernova is a massive explosion of a star that occurs under two possible scenarios. The first is that a white dwarf star undergoes a nuclear based explosion after it reaches its Chandrasekhar limit from absorbing mass from a neighboring star (usually a red giant). The second, and more common, cause is when a massive star, usually a red giant, reaches iron in its nuclear fusion (or burning) processes. Iron has one of the highest binding energies of all of the elements and is the last element that can be produced by nuclear fusion, exothermically. All nuclear fusion reactions from here on are endothermic and so the star loses energy. The star's gravity then pulls its outer layers rapidly inward. The star collapses very quickly, and then explodes. Blah Image of Sirius A and Sirius B taken by the Hubble Space Telescope. ... This article is about the astronomical object. ... The Chandrasekhar limit, is the maximum mass possible for a white dwarf (one of the end stages of stars when they cool down) and is approximately 3 × 1030 kg, around 1. ... Cross section of a red giant showing nucleosynthesis and elements formed 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. ... Cross section of a red giant showing nucleosynthesis and elements formed 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. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... Binding energy is the energy required to disassemble a whole into separate parts. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... In thermodynamics, the word exothermic describes a process or reaction that releases energy in the form of heat. ... In thermodynamics, the word endothermic describes a process or reaction that absorbs energy in the form of heat. ...


Elements fused

Composite image of Kepler's supernova from pictures by the Spitzer Space Telescope, Hubble Space Telescope, and Chandra X-ray Observatory.
Composite image of Kepler's supernova from pictures by the Spitzer Space Telescope, Hubble Space Telescope, and Chandra X-ray Observatory.

Due to the large amounts of energy released in a supernova explosion much higher temperatures are reached than stellar temperatures. Higher temperatures allow for an environment where elements up to the atomic mass of 254 are formed, californium being the heaviest known, though it is seen only as a synthetic element on Earth. In nuclear fusion processes in stellar nucleosynthesis, the maximum weight for an element fused is that of nickel, reaching an isotope with an atomic mass of 56. Fusion of elements between silicon and nickel occurs only in the largest of stars, which end as supernova explosions (see Silicon burning process). A neutron capture process known as the s process which also occurs during stellar nucleosynthesis can create elements up to bismuth with an atomic mass of approximately 209. However, the s process occurs primarily in low-mass stars that evolve more slowly. Download high resolution version (750x750, 53 KB)Remnants of Keplers Supernova (SN 1604). ... Download high resolution version (750x750, 53 KB)Remnants of Keplers Supernova (SN 1604). ... Supernova 1604, also known as Keplers Supernova or Keplers Star, was a supernova in the Milky Way, in the constellation Ophiuchus. ... The Spitzer Space Telescope (formerly the Space Infrared Telescope Facility [SIRTF]) is an infrared space observatory, the fourth and final of NASAs Great Observatories. ... -1... For other uses, see Chandra (disambiguation). ... The atomic mass of a chemical element is the mass of an atom at rest, most often expressed in unified atomic mass units. ... General Name, Symbol, Number californium, Cf, 98 Chemical series actinides Group, Period, Block n/a, 7, f Appearance unknown, probably silvery white or metallic gray Atomic mass (251) g·mol−1 Electron configuration [Rn] 5f10 7s2 Electrons per shell 2, 8, 18, 32, 28, 8, 2 Physical properties Phase solid... The chemical elements labelled as synthetic are unstable, with a half-life so short (ranging from a fraction of millisecond to a few million years) relative to the age of the Earth that any atoms of that element that may have been present when the Earth formed have long since... Adjectives: Terrestrial, Terran, Telluric, Tellurian, Earthly Atmosphere Surface pressure: 101. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... 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 astrophysics, silicon burning is a nuclear fusion reaction which occurs in massive stars. ... This article or section does not cite its references or sources. ... 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. ... This article or section does not cite its references or sources. ...


The R-Process

During supernova nucleosynthesis, the r process (r for rapid) creates very neutron-rich heavy isotopes, which decay after the event to the first stable isobar, thereby creating the neutron-rich stable isotopes of all heavy elements. This neutron capture process occurs in high neutron density with high temperature conditions. In the r process, any heavy nuclei are bombarded with a large neutron flux to form highly unstable neutron rich nuclei which very rapidly undergo beta decay to form more stable nuclei with higher atomic number and the same atomic weight. The neutron flux is astonishingly high, about 1022 neutrons per square centimeter per second. First calculation of a dynamic r process, showing the evolution of calculated results with time [2], also suggested that the r process abundances are a superposition of differing neutron fluences. Small fluence produces the first r process abundance peak near atomic weight A=130 but no actinides, whereas large fluence produces the actinides uranium and thorium but no longer contains the A=130 abundance peak. These processes occur in a fraction of a second to a few seconds, depending on details. Hundreds of subsequent papers published have utilized this time-dependent approach. Interestingly, the only modern nearby supernova, 1987A, has not revealed r process enrichments. Modern thinking is that the r process yield may be ejected from some supernovae but swallowed up in others as part of the residual neutron star or black hole. 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. ... In the various subfields of physics, there exist two common usages of the term flux, both with rigorous mathematical frameworks. ... A semi-accurate depiction of the helium atom. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... It has been suggested that List of elements by atomic number be merged into this article or section. ... ... This article is being considered for deletion in accordance with Wikipedias deletion policy. ... Look up second in Wiktionary, the free dictionary. ...


References

  • 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, "Handbook of Isotopes in the Cosmos", Cambridge University Press, 2003, ISBN 0 521 823811.

The Reviews of Modern Physics are a journal of the American Physical Society. ... Physical Review is one of the oldest and most-respected scientific journals publishing research on all aspects of physics. ...

Notes

  1. ^ Woosley, S.E., W. D. Arnett and D. D. Clayton (1973). "Explosive burning of oxygen and silicon". THE ASTROPHYSICAL JOURNAL SUPPLEMENT 26: 231-312. 
  2. ^ P. A. Seeger, W.A. Fowler, D. D. Clayton (1965). "Nucleosynthesis of heavy elements by neutron capture". THE ASTROPHYSICAL JOURNAL SUPPLEMENT 11: 121-166. 

See also

A sphere of plutonium surrounded by neutron-reflecting blocks of tungsten carbide. ... Multiwavelength X-ray image of the remnant of Keplers Supernova, SN 1604. ... 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. ... 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. ...

External links

  • Atom Smashers Shed Light on Supernovae, Big Bang Sky & Telescope Online, April 22, 2005
  • G. Gonzalez, D. Brownlee, P. Ward (2001). "The Galactic Habitable Zone: Galactic Chemical Evolution" (PDF). Icarus 152: 185-200. 

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