AST-1A Lecture Notes - Lecture 14: Electron Degeneracy Pressure, Degenerate Matter, Solar Mass
Document Summary
Once the star exhausts the helium in its core, the carbon-oxygen core begins to contract and heat up. If the star"s initial mass was greater than about 8 times the mass of our sun, the carbon core will become sufficiently hot to ignite the carbon. The carbon can fuse into oxygen, neon, sodium, magnesium, helicon, etc. The formation of new elements is called nucleosythesis. Theories of how nucleosynthesis proceeds in massive stars have been very successful in predicting the relative abundances of the elements. Once the core reaches iron-56, the most stable nucleus, it can no longer generate energy through nuclear fusion. All fusion reactions beyond this point require that energy be added (they are endothermic). At this point, the star resembles an onion, with many shells fusing different elements. The binding energy is a measure of the force holding the nucleus of an atom together. The higher the binding energy, the more tightly bound is the nucleus.
