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In astrophysics, stellar nucleosynthesis is the creation of chemical elements by nuclear fusion reactions within stars. Stellar nucleosynthesis has occurred since the original creation of hydrogen, helium and lithium during the Big Bang. As a predictive theory, it yields accurate estimates of the observed abundances of the elements.
The x-process in cosmic rays is the primary means of nucleosynthesis for the five stable isotopes of lithium, beryllium, and boron. [3] As the proton–proton chain reaction cannot proceed beyond 4 He due to the unbound nature of 5 He and 5 Li, [ 4 ] and the triple-alpha process skips over all species between 4 He and 12 C, these elements are ...
The products of stellar nucleosynthesis are generally dispersed into the interstellar gas through mass loss episodes and the stellar winds of low mass stars. The mass loss events can be witnessed today in the planetary nebulae phase of low-mass star evolution, and the explosive ending of stars, called supernovae , of those with more than eight ...
Advanced Placement (AP) Human Geography (also known as AP Human Geo, AP Geography, APHG, AP HuGe, APHug, AP Human, HuGS, AP HuGo, or HGAP) is an Advanced Placement social studies course in human geography for high school, usually freshmen students in the US, culminating in an exam administered by the College Board.
One of these physical processes has to do with the characteristics of the host star of a planet, and how stellar influences on an origin of life setting can dictate how life evolves, if at all. Life required an energy source at its origin, and scientists have long speculated that this energy source could have been the ultraviolet radiation that ...
Fusing with additional helium nuclei can create heavier elements in a chain of stellar nucleosynthesis known as the alpha process, but these reactions are only significant at higher temperatures and pressures than in cores undergoing the triple-alpha process.
Logarithm of the relative energy output (ε) of proton–proton (PP), CNO and Triple-α fusion processes at different temperatures (T). The dashed line shows the combined energy generation of the PP and CNO processes within a star.
All chemical elements derive from stellar nucleosynthesis except for hydrogen and some helium and lithium. Basic chemical ingredients of life – the carbon-hydrogen molecule (CH), the carbon-hydrogen positive ion (CH+) and the carbon ion (C+) – can be produced by ultraviolet light from stars. [ 93 ]