Home > Stellar nucleosynthesis

The processes involved were elucidated over a number of years from 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.

In 1920, Arthur Eddington, on the basis of the precise mesurements of atoms by F.W Aston, was the first to suggest that stars obtained their energy from nuclear fusion of hydrogen to 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 barrierThe Coulomb barrier named after Coulomb, is the electrostatic repulsion of two point charges. Overcoming the Coulomb barrier is essential for achieving nuclear fusion. with :k Coulomb's constant :e charge of electron :r separation.. The Gamow factor was used in the decade that followed by Atkinson and HoutermansFriedrich Georg Houtermans ( January 22, 1903 March 1, 1966) was a physicist born in Zoppod near Danzig (today Gdansk, Poland). Houtermans made important contributions to geochemistry and cosmochemistry. External references Houtermans, F. 1953) "Determina and later by Gamow himself and TellerLawrence Livermore National Laboratory. Edward Teller (original Hungarian name Teller Ede ( January 15, 1908 September 9 2003) was an Hungarian-born American nuclear physicist of Jewish descent. He was known colloquially as "the father of the hydrogen bom to derive the rate at which nuclear reactions would proceed at the high temperatures believed to exist in stellar interiors.

In 1939Events January-June January 2 End of term for Frank Finley Merriam, 28th Governor of California. He is succeeded by Culbert Levy Olson. January 24 Earthquake kills 30. 000 in Chile about 50. 000 sq mi razed January 26 Falangists take Barcelona January 26, in a paper entitled "Energy Production in Stars", Hans BetheHans Albrecht Bethe (born July 2, 1906), is an American physicist from Strassburg (then part of Germany, now Strasbourg, France). Bethe (pronounced Bey-ta studied physics at Frankfurt and obtained his doctorate from the University of Munich. He left Germa analyzed the different possibilities for reactions by which hydrogen is fused into helium. He selected two process that he believed are the source of energy in stars. The first one, the proton-proton chain, is the dominant energy source in stars low masses about like the Sun or smaller. The second process, the carbon-nitrogen-oxygen cycle, which was also considered by Carl von Weizsäcker in 1938, is most important in more massive stars.

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.

The most important such reactions are:

• Hydrogen burning:
  • The proton-proton chain
  • The carbon-nitrogen-oxygen cycle
• Helium burning:
  • The triple-alpha process
  • The alpha process
• Heavier elements burning:
  • Carbon burning process
  • Oxygen burning process
  • Silicon burning process
• Production of elements heavier than Iron:
  • Neutron capture:
    • The R-process
    • The S-process
  • Proton capture:
    • The P-process