Stars: Physical Properites

• masses: binary stars
• luminosity, flux, and a reprise of the inverse square law
• distance: parallax

Stars: Stability, Lifespan, and Energy Supply

Nuclear Reactions in Stars and the Universe

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!