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单词 Urca process
释义
Urca process

Physics
  • A process, first postulated by George Gamow (1904–68) and Mario Schoenberg (1914–90) in 1941, in which much of the large quantity of energy generated by the collapse of a large star to produce a neutron star (see supernova) is carried away by neutrinos. This process explains why stars can collapse rapidly rather than have this collapse delayed by the heat generated. Neutrinos created in this way have been detected. The Urca process is named after the Casino da Urca, which was a nightclub in Rio de Janeiro that Gamow and Schoenberg were visiting when they had their idea.


Astronomy
  • A cycle of nuclear reactions in which an electron is absorbed by a nucleus and is subsequently re-emitted as a beta particle (a fast electron) with the generation of a neutrino–antineutrino pair. The process makes no change to the composition of the nucleus, but removes energy from it in the form of the neutrino and antineutrino. While insignificant in ordinary stars, it is important at very high densities and temperatures such as those which give rise to supernovae. The process is named after the Urca Casino in Rio de Janeiro, where it was said that money disappeared as rapidly as energy from the stars.


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