ASTR 121 Lecture Notes - Lecture 6: Nuclear Fusion, Binding Energy, Pressure Gradient
1 Mar 2018
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Document Summary
Lecture 06: life as a high mass star. Most of the elements in the universe heavier than helium are formed in high mass stars. High mass core temperatures permit more advanced fusion reactions. Supernovae generate some to most of the remaining elements by fusion and fission. H fuses to he around he core (not flash) He fuses to c in core, h fuses to he is shell. Things get complicated if stars change mass suddenly. High-mass stars can make elements as heavy as iron in their cores and their explosive deaths- supernovae- create a large deaths- supernovae- create a large fraction of the heavy elements of the periodic table. Some can be made by inspiraling neutron stars. Helium can sometimes form carbon in low mass stars. Cno cycle can change carbon into nitrogen and oxygen. Mid to high mass stars fuse h to he at a higher rate using carbon nitrogen and oxygen as a catalyst.
