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lecture8 - Ring nebula! Late stellar Evolution & !...

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Late stellar Evolution & Death !! Ring nebula Catseye Planetary nebulae How do we get to the planetaries and what happens after ??
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: H in core converted to He => main sequence phase ends 1) H burns in shell around core 3) core collapses slowly => higher T 3) outer radius increases to ~ 1 AU (100 R sun ) = red giant 4) At 100 million K, 3 He ! C 6) core He converted to C 8) C + He ! O + He ! Ne + He ! Mg + He ! Si synthesize heavy elements up to iron (Fe) virtually all elements Be => Fe ! He fusion w/i core H fusion in shell surrounding core H fusion w/i core e’s (fermions) => must obey Pauli exclusion no 2 e’s w/ same space and spin wave functions as gas compresses, e’s must go to higher energy states for degenerate gas, P = 1.06 x 10 13 ! 5/3 ==> ! 4/3 (relativistic) [ for ideal gas, P = 8.6 x 10 14 ! (T / 10 7 ) ] for deg. gas , P no longer depends on T !! ==> lose temperature regulation and stability ==> get 10 11 L sun (absorbed in raising gas out of degeneracy) ==> most He => C (requires 200 x 10 6 K to fuse) when * core ==> iron (Fe), fusion can no longer generate energy to replace luminosity lost at surface ==> star core cools ==> collapse of star if star is massive => supernova explosion
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lecture8 - Ring nebula! Late stellar Evolution & !...

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