Stellar Spectra and the Hertzsprung-Russell Diagram

• Classification: spectral line strengths lead to spectral types
• a census of stars: the Hertzsprung-Russell diagram
  real data: Hipparchos
  observer's version (i.e., axes in observational units)
  theoretical version (i.e., axes in underlying physical units)
• animated HR diagram
• stellar radii: the movie

Mass, Luminosity, and Lifespan

• Mass-luminosity relation plotted for main sequence stars
• implications for HR diagram
  HR diagram comparison: nearest vs brightest (highest flux) stars

The Life Cycle of of a 1 M_sun star

• protostar birth in molecular clouds
• adulthood: the main sequence
• Red giants and implications for HR diagrams like this and this
• Helium flash
• Helium burning: horizontal branch
• Death throes: asymptotic giant branch
• 1M_sun HR diagram: evolutionary path, animation

Testing Stellar Evolution Theory: Star Clusters

• open clusters: stellar kindergartens
  • the Plieades image and HR diagram
  • the Hyades image and HR diagram
  • h and chi Persei image and HR diagram
• globular clusters: stellar retirement communities
  • M55 image and HR diagram
  • M5 image, zoom, and HR diagram