• Stars are classified using the Hertzsprung-Russell (HR) diagram
• This is a plot of:
  • The?luminosity?on the y-axis
    • This is from?dim?(at the bottom) to?bright?(at the top)

     

  • The?temperature?on the x-axis
    • This is from?hot?(on the left) to?cool?(to the right)
    • This is normally in?Kelvin

     

   

The Hertzsprung-Russell Diagram

• The main features of the Hertzsprung-Russell diagram are:
  • Most stars lie on the?Main?Sequence. This is the band of stars going from top left to bottom right
  • Below the main sequence (and slightly to the left) are the?White Dwarfs
  • Above the main sequence on the right-hand side are the?Red Giants
  • Above those are the?Red Supergiants

   

• This means the white dwarfs are?dimmer?and?hotter?than the red giants which are?brighter?and?cooler
• Sometimes, the absolute magnitude is on the y-axis instead
  • Remember this will still go from dimmest (highest?number) at the bottom to brightest (lowest?number) at the top!