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The Death of High Mass Stars: 8 Solar Masses and up. All stars will live to see the Red Giant phase, then… • Low mass stars never reach 600 million K in their cores, so fusion of C is impossible. • Larger stars can, here is what happens... C Ne and Mg Ne O and Mg O Si ,S, Mg, & P Si Fe Core Temp= 600 mil K Core Temp= 1.2 bil K Core Temp= 1.5 bil K Core Temp= 2.7 bil K Relative Sizes of the Solar System Sun compared to larger stars Sun compared to SUPER massive stars AHHHHHHHHH! Iron Core!!! • Iron does NOT give off energy during in fusion. It takes energy IN for fusion to occur. • If no energy is produced in the core! Then gravity wins and pulls matter towards the center. • Remember, the core was already 2.7 bil K, before gravity pulls. With the increase in pressure, it gets even hotter! Supernova • The collapsing star reaches core temps over 10 billion K!!! • Densities can reach upwards of 1018kg/m3. At this density, neutrons are brought into contact. • This causes a rebound effect (with a vengeance) creating a shock wave. • Blasts all layers above into space. This blast creates all elements more massive than Fe. Characteristics of Supernova • Most energetic event in the universe!!! • Once the core is iron, it takes just seconds for the Supernova to occur. • The brightness of Supernova can actually rival the brightness of the galaxy they are found in. If found in our galaxy, they are often so bright they can be seen during the day!!! Supernova 1987a • Located in a nearby dwarf galaxy called Large Magellanic Cloud. 170,000 ly away (orbits Milky Way). • Energy released was equal to 1027 nuclear warheads. SN 2006GY is brighter than the galaxy (NGC 1260 ) it is found in. Supernova in distant Galaxy • The only time an individual star can be seen in distant galaxies. • SN clearly rivals the brightness of the entire galaxy it is in. Crab Nebula (M1) • Supernova remnant (past explosion). Occurred in 1054 AD and observed by Chinese astronomers. • 1800 parsecs away (5400 light years). • Nebula spans “only” 2 parsecs- about 7 light years (considered young). • Was seen for 1 month during the day. • Found in between the horns of Taurus. Where did I come from? • You are star stuff!!! The elements that make up everything around you are star stuff. • Primordial Elements- hydrogen and helium are believed to have been here since right after the “Big Bang.” – Mostly H and He, with some Li and Be as well. • All remaining elements came from stars. Everything past iron was created during supernova explosions. 2 Types of Supernovae • Type I: Carbon Detonation – Part of a binary system where a white dwarf gains enough mass to overcome electron degeneracy. • Type II: Core Collapse – Core fuses until Fe Type I Supernova Type II SN: VERY MASSIVE STAR Type II Supernova