“nucleosynthesis”的概念、定义、翻译、参考文献-科学参考

nucleosynthesis

Physics

The synthesis of chemical elements by nuclear processes. There are several ways in which nucleosynthesis can take place. Primordial nucleosynthesis took place very soon after the big bang, when the universe was extremely hot. This process was responsible for the cosmic abundances observed for light elements, such as helium. Explosive nucleosynthesis can occur during the explosion of a supernova. Many of the elements that are heavier than iron are made in this way. However, stellar nucleosynthesis, which takes place in the centre of stars at very high temperatures, is the principal form of nucleosynthesis. The exact process occurring in stellar nucleosynthesis depends on the temperature, density, and chemical composition of the star. The synthesis of helium from protons and of carbon from helium can both occur in stellar nucleosynthesis. Some light elements, such as boron, are made by spallation. See also carbon cycle; early universe; stellar evolution.

Astronomy

The process of creating elements by nuclear reactions. Helium was produced by nucleosynthesis in the few minutes following the Big Bang. Helium and heavier elements are built up by nucleosynthesis inside stars. First, hydrogen is converted to helium by the proton–proton reaction or the carbon–nitrogen cycle. When the hydrogen-to-helium phase ends, the triple-alpha process takes over. Successively heavier elements up to iron are then synthesized, each in turn using the product of the previous reaction. If a star becomes a supernova, the heaviest possible nuclei are formed and are ejected into interstellar space. New generations of stars forming from the enriched medium have a higher heavy element content than old stars. See also r-process; s-process.

Chemistry

The synthesis of chemical elements by nuclear processes. There are several ways in which nucleosynthesis can take place. Primordial nucleosynthesis took place very soon after the big bang, when the universe was extremely hot. This process was responsible for the cosmic abundances observed for light elements, such as helium. Explosive nucleosynthesis can also occur during the explosion of a supernova. However, stellar nucleosynthesis, which takes place in the centre of stars at very high temperatures, is now the principal form of nucleosynthesis. The exact process occurring in stellar nucleosynthesis depends on the temperature, density, and chemical composition of the star. The synthesis of helium from protons and of carbon from helium can both occur in stellar nucleosynthesis. Nucleosynthesis also occurs when a very large star collapses to a neutron star in a supernova explosion after its nuclear ‘fuel’ is exhausted or when two neutron stars collide. Another process by which nucleosynthesis can occur is spallation. See also origin of elements.

Geology and Earth Sciences

The process by which elements are formed. Modern theories suggest that nucleosynthesis is intimately linked with the stages in the life-cycle of stars (stellar evolution), and that, commencing with hydrogen, heavier elements are created by nuclear fusion of lighter nuclides at the temperatures and pressures existing in the cores of stars. Because the lighter elements are consumed to produce energy these thermonuclear reactions are referred to as ‘burning’, although they have nothing to do with combustion. The stages of stellar evolution conform well with the overall pattern of peaks and troughs in the cosmic abundance of elements in order of increasing atomic number (Z). During the first and longest (main-sequence) phase, hydrogen (which is by far the most abundant element of the stellar material) is consumed to produce helium (hydrogen burning). Hydrogen burning is followed in turn by helium burning, carbon and oxygen burning, and silicon burning, each phase producing heavier elements from lighter ones. The heaviest elements are formed in the last stages in the sequence: the equilibrium (e) process (coinciding with the ‘iron peak’ elements, Cr, Mn, Fe, Co, and Ni), followed by the ‘slow-neutron (s) process producing elements up to Bi (atomic number 83), and finally (in supernova events) the rapid-neutron (r) process producing elements with atomic number greater than 83. See also protostar.

单词	nucleosynthesis
释义	nucleosynthesis Physics The synthesis of chemical elements by nuclear processes. There are several ways in which nucleosynthesis can take place. Primordial nucleosynthesis took place very soon after the big bang, when the universe was extremely hot. This process was responsible for the cosmic abundances observed for light elements, such as helium. Explosive nucleosynthesis can occur during the explosion of a supernova. Many of the elements that are heavier than iron are made in this way. However, stellar nucleosynthesis, which takes place in the centre of stars at very high temperatures, is the principal form of nucleosynthesis. The exact process occurring in stellar nucleosynthesis depends on the temperature, density, and chemical composition of the star. The synthesis of helium from protons and of carbon from helium can both occur in stellar nucleosynthesis. Some light elements, such as boron, are made by spallation. See also carbon cycle; early universe; stellar evolution. Astronomy The process of creating elements by nuclear reactions. Helium was produced by nucleosynthesis in the few minutes following the Big Bang. Helium and heavier elements are built up by nucleosynthesis inside stars. First, hydrogen is converted to helium by the proton–proton reaction or the carbon–nitrogen cycle. When the hydrogen-to-helium phase ends, the triple-alpha process takes over. Successively heavier elements up to iron are then synthesized, each in turn using the product of the previous reaction. If a star becomes a supernova, the heaviest possible nuclei are formed and are ejected into interstellar space. New generations of stars forming from the enriched medium have a higher heavy element content than old stars. See also r-process; s-process. Chemistry The synthesis of chemical elements by nuclear processes. There are several ways in which nucleosynthesis can take place. Primordial nucleosynthesis took place very soon after the big bang, when the universe was extremely hot. This process was responsible for the cosmic abundances observed for light elements, such as helium. Explosive nucleosynthesis can also occur during the explosion of a supernova. However, stellar nucleosynthesis, which takes place in the centre of stars at very high temperatures, is now the principal form of nucleosynthesis. The exact process occurring in stellar nucleosynthesis depends on the temperature, density, and chemical composition of the star. The synthesis of helium from protons and of carbon from helium can both occur in stellar nucleosynthesis. Nucleosynthesis also occurs when a very large star collapses to a neutron star in a supernova explosion after its nuclear ‘fuel’ is exhausted or when two neutron stars collide. Another process by which nucleosynthesis can occur is spallation. See also origin of elements. Geology and Earth Sciences The process by which elements are formed. Modern theories suggest that nucleosynthesis is intimately linked with the stages in the life-cycle of stars (stellar evolution), and that, commencing with hydrogen, heavier elements are created by nuclear fusion of lighter nuclides at the temperatures and pressures existing in the cores of stars. Because the lighter elements are consumed to produce energy these thermonuclear reactions are referred to as ‘burning’, although they have nothing to do with combustion. The stages of stellar evolution conform well with the overall pattern of peaks and troughs in the cosmic abundance of elements in order of increasing atomic number (Z). During the first and longest (main-sequence) phase, hydrogen (which is by far the most abundant element of the stellar material) is consumed to produce helium (hydrogen burning). Hydrogen burning is followed in turn by helium burning, carbon and oxygen burning, and silicon burning, each phase producing heavier elements from lighter ones. The heaviest elements are formed in the last stages in the sequence: the equilibrium (e) process (coinciding with the ‘iron peak’ elements, Cr, Mn, Fe, Co, and Ni), followed by the ‘slow-neutron (s) process producing elements up to Bi (atomic number 83), and finally (in supernova events) the rapid-neutron (r) process producing elements with atomic number greater than 83. See also protostar.
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