Space.com movie: "Supernovae" [10'04"]
     [Midterm 3 material]
     Massive m. s. star death
          Fusion past Fe in cores cannot release energy
          Fusion now _absorbs_ energy, core gravitationally collapses
     Outer layers explode as type II supernovae 
          Core becomes neutron star
          All elements heavier than iron form during supernovae
     Expanding supernova remnant surrounds neutron star
     Rotating neutron star = lighthouse "pulsar"

     [Quiz 10 material]
     Extremely massive m. s. star cores become black holes
     Mass transfer in binary systems from star to white dwarf
          Fresh hydrogen undergoes fusion on surface of white dwarf
          [Novae = only surface explodes, white dwarf survives]
          [Type Ia supernovae = entire white dwarf explodes]