Cepheid Star

  • Variable stars
  • Large, yellow, pulsating stars
  • Rise rapidly to maximum light then falls more slowly to minimum light
  • Several hundred known in our galaxy
  • The period is directly related to luminosity
  • Has a shell of partially ionized helium
    • Shell is effective at absorbing photons (energy from the core)
      1. The layer heats up and expands, making the star bigger and brighter
      2. Shell gets bigger and spread thin, stops absorbing photons
      3. Shell starts contracting and shrinking
      4. Repeat steps


Type 1

  • Metal-rich
  • Brighter

Type 2

Astronomy Star