Stellar ignition, or star ignition, is the initiation of the nuclear fusion reactions that power the Sun and other stars. Ideas about stellar ignition by heat produced during gravitiational collapse developed during the early 20th century. Before nuclear fission was discovered, no one for more than six decades thought to question the concept. The idea that natural fusion reactions are ignited by natural fission reactions was a fundamentally new and revolutionary concept with profound astrophysical implications.7) [1] History Stellar energy source At the beginning of the 20th century, understanding the nature of the energy source that powers the Sun and other stars was one of the most important problems in physical science. Initially, the idea was that as the dust and gas collapsed to form a star, it would heat. In other words, gravitational potential energy would be converted into heat. Soon, however, calculations were made showing that the energy released would only be sufficient to power a star for a few million years at most and certainly life has existed on Earth for a longer time. The discovery of radioactivity, especially thermonuclear fusion,[1] and the developments that followed led to the idea that thermonuclear fusion reactions power the Sun and other stars.[2][3] For work on the theory of stellar nucleosynthesis, Hans Albrecht Bethe was awarded the 1967 Nobel Prize in Physics. Thermonuclear fusion Thermonuclear fusion reactions are called "thermonuclear" because temperatures on the order of a million degrees Celsius are required. The principal energy released from the detonation of hydrogen bombs comes from thermonuclear fusion reactions. The high temperatures necessary to ignite H-bomb thermonuclear fusion reactions comes from their A-bomb nuclear fission triggers. Each hydrogen bomb is ignited by its own small nuclear fission A-bomb. By 1938, the idea of thermonuclear fusion reactions as the energy source for stars had been reasonably well developed, but nuclear fission had not yet been discovered.[4] Astrophysicists assumed that the million-degree temperatures necessary for stellar thermonuclear ignition would be produced by the in-fall of dust and gas during star formation and have continued to make that assumption to the present, although clearly there have been signs of potential trouble with the concept. Heating by the in-fall of dust and gas takes place at the surface of the forming star. This heating is off-set by radiation from the surface, which is a function of the fourth power of temperature (T4), which for T = 1,000,000 becomes a huge loss factor. Generally, in numerical models of protostellar collapse, thermonuclear ignition temperatures, on the order of a million degrees Celsius, are not attained by the gravitational in-fall of matter without assumption of an additional shockwave-induced sudden flare-up[5][6] or by result-optimizing the model-parameters, such as opacity and rate of in-fall.[7] Nuclear fission After demonstrating the feasibility for planetocentric nuclear fission reactors,[8][9] including Earth’s georeactor, J. Marvin Herndon proposed that thermonuclear fusion reactions in stars, as in hydrogen bombs, are ignited by self-sustaining, neutron-induced nuclear fission.[10] This concept is fundamentally different in that heating takes place at the protostar centre, not at the surface where heat loss occurs. Moreover, the ability of nuclear fission reactions to ignite thermonuclear fusion reactions has been experimentally verified with each successful hydrogen bomb detonation. The idea that stars are ignited by nuclear fission triggers opens the possibility of stellar non-ignition, a concept which may have fundamental implications bearing on the nature of dark matter[10] and dark galaxies.[11] Now, there is reason to think that so-called hot Jupiter exoplanets,[12] which have densities less than that of Jupiter, may derive much of their internal heat production from interfacial thermonuclear fusion reactions ignited by nuclear fission.[13] References 1. ^ Oliphant, M.L., P. Harteck, and E. Rutherford (1934). "Transmutation effects observed with heavy hydrogen". Nature 133: 413. 2. ^ Gamow, G. and E. Teller (1938). "The rate of selective thermonuclear reactions". Phys. Rev. 53: 608–9. 3. ^ Bethe, H.A. (1938). "Energy production in stars". Phys. Rev. 55: 434–56. 4. ^ Hahn, O. and F. Strassmann (1939). "Uber den Nachweis und das Verhalten der bei der Bestrahlung des Urans mittels Neutronen entstehenden Erdalkalimetalle". Die Naturwissenschaften 27: 11–5. 5. ^ Hayashi, C. and T. Nakano (1965). "Thermal and dynamic properties of a protostar and its contraction to the stage of quasi-static equilibrium". Prog. Theor. Physics 35: 754–75. 6. ^ Larson, R.B. (1984). "Gravitational torques and star formation". Mon. Not. R. Astr. Soc. 206: 197–207. 7. ^ Stahler, S.W., et al. (1994). "The early evolution of protostellar disks". Astrophys. J. 431: 341–58. 8. ^ Herndon, J.M. (1992). "Nuclear fission reactors as energy sources for the giant outer planets". Naturwissenschaften 79: 7–14. 9. ^ Herndon, J.M. (1993). "Feasibility of a nuclear fission reactor at the center of the Earth as the energy source for the geomagnetic field". J. Geomag. Geoelectr. 45: 423–37. 10. ^ a b Herndon, J.M. (1994). "Planetary and protostellar nuclear fission: Implications for planetary change, stellar ignition and dark matter". Proc. R. Soc. Lond A455: 453–61. 11. ^ Herndon, J.M. (13 April 2006). Thermonuclear ignition of dark galaxies. 12. ^ Charbonneau, D., et al. (19 Oct. 2006). Precise radius estimates for the exoplanets WASP-1b and WASP-2b. 13. ^ Herndon, J.M. (20 Dec. 2006). "New concept for internal heat production in hot Jupiter exo-planets". Retrieved from "http://en.wikipedia.org/"
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