ASTR 20 Lecture Notes - Lecture 27: Hubble Deep Field, Crab Nebula, Degenerate Matter
Document Summary
Iron is a dead end for fusion because nuclear reactions involving iron do not release energy. (iron has lowest mass per nuclear particle) To create heavier elements than iron by fusion, need to put energy in. Iron builds up in the core until degeneracy pressure can no longer resist gravity. The core then suddenly collapses, creating a supernova explosion. Can be more luminous than the entire host galaxy (100 billion stars) Core degeneracy pressure goes away because electrons combine with protons, making neutrons and neutrinos. Neutrons collapse to the center, forming a neutron star (more massive than the sun) If the core is even more massive, a black hole can result. Energy released by the collapse of the core drives outer layers into space. The crab nebula is the remnant of the supernova seen in a. d. 1054. Summary of stellar evolution- the role of mass. A star"s mass determines its entire life story because it determines its core temperature.
