PCS 181 Lecture Notes - Lecture 5: Milky Way, Sn 1987A, Large Magellanic Cloud
20 Apr 2016
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Document Summary
Adeath of middleweight stars: star undergoes several ted giant phases, producing ever-heavier elements in the core. 1 day: not enough mass to raise temperature high enough for iron to fuse, material gets ejected into space, leaving a dense core, supernova explosion. 10 seconds supernovae: when star has an iron core, iron will not fuse outward radiation pressure decreases, star collapses inward, compressing core. 4: protons and electrons are forced to merge to produce neutrons, neutrons reach max density and collapsing layers of star strike this tight ball of neutrons. Massive stars live for a few million years but go supernova in seconds. A supernova event can shine 108 times brighter than the progenitor star. The bright ejecta grow more diffuse and dim over a few years. We observe very few supernovae in our milky way galaxy. Only ~5% of stars have sufficient mass. We observe ~2 supernovae every hundred years in other galaxies.
