The Brightest Stars

Stars: Physical Properties

• Apparent brightness
• Colors
  
  • Orion
  • Southern Cross optical image, objective prism
  • filters: commonly used wavelength bands; a filter wheel
    
  • multiwavelength comparison: Plieades star cluster
• Luminosity
• Distance: parallax
  RECONS project data on the 100 nearest stars
  nearest stars mapped
  
• Mass: from binary systems

  visual binaries: Mizar orbit

  spectroscopic binaries

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)

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