Fusion in the Sun

• Reactions and products
  • deuterium
  • positrons
  • neutrinos
• Where does the energy come from?
• A prizewinning theory

The Evidence: Solar Neutrinos

• Radiochemical experiments
  • The pioneer: Ray Davis and the Homestake Mine experiment
  • GALLEX experiment (Gran Sasso, Italy): gallium tank
• Scattering experiments
  • Super-Kamiokande (Japan); Super-K neutrino image of the Sun
    
  • Sudbury Neutrino Observatory (Canada); detector image
  • Borexino (Italy); detector image
• The 2002 Nobel Prize in Physics
• Coda: Cosmic Gall, by John Updike

Life Cycles of Stars

• birth in cold gas clouds
• main sequence: hydrogen burning
• helium burning
• low mass stars:
  • ejection of planetary nebula: Ring, Cat's Eye
  • compact cinder: white dwarf
• high mass stars:
  • cycles of contraction and burning
  • gravitational collapse of iron core

Supernova Explosions: Death of Massive Stars

• explosions: SN 1987A, SN 1994D
  SN1572 (Tycho): Tycho's sketch in 1572; X-rays today
• ejecta: Veil nebula, Crab nebula
• compact cinders: Crab nebula X-ray zoom, Cas A neutron star, Guitar nebula--duck!