Hertzsprung-Russell Diagram

The Hertzsprung-Russell Diagram is a graphical tool that astronomers use to classify stars according to their luminosity, spectral type, color, temperature and evolutionary stage.

Stars in the stable phase of hydrogen burning lie along the Main Sequence according to their mass.

After a star uses up all the hydrogen in its core, it leaves the main sequence and moves towards the red giant branch.

The most massive stars may also become red supergiants, in the upper right corner of the diagram.

The lower left corner is reserved for the white dwarfs.

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