H-R diagram


  • Devised by Ejnar Hertzsprung and Henry Russell, the Hertzsprung-Russell (H-R) diagram is a graph to plot the temperature of stars against their brightness. The temperature of a star is indicated by its colour,
  • Cool stars are red or reddish-yellow
  • Hot stars burn white or blue.
  • Medium-sized stars form a diagonal band called the main sequence across the graph.
  • The whiter and hotter a main sequence star is, the brighter it shines. White stars and blue-white stars are usually bigger and younger.
  • The redder and cooler a star is, the dimmer it glows. Cool red stars tend to be smaller and older.
  • Giant stars and white dwarfs lies to either side of the main sequence stars.
  • The H-R diagram shows how bright each star should be. If the star actually looks dimmer, it must be further away.

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