Nuclear Fusion and Nucleosynthesis

As snch a star ages and accnmnlates helinm, it begins to contract under the in-flnence of its immense gravity. As it contracts, its helium core heats up when it reaches a temperatnre of abont 10 K, a stage of helium burning begins. The first reaction that occnrs is 

This reaction is written as an eqnilibrinm because the Be quickly reverts to helium nuclei with a half-life of only 2 X 10 s. Even with this short half-life, the Be nnclei are believed to occasionally react with alpha particles to form stable 

The overall effect of the helium-burning phase of a star s life is to convert three helium nuclei to a carbon nucleus, just as helium was formed from four hydrogen nuclei in the hydrogen-burning phase. The density of the core of a star that is burning helium is on the order of 10 g cm.  

This process of nucleosynthesis continues beyond the formation of to produce and The stars in this stage are classified as red 

Heavy elements can also be produced in particle accelerators, which accelerate ions to high speeds, causing collisions that generate the new elements. Technetium, for example, is not found in nature but was first produced in 1937 when high-energy deuterons were directed at a molybdenum source  

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