11.23: The Four Hertzsprung-Russell Diagram Stellar Groups
The H-R Diagram plots stars such that there are four major groups.
The Supergiants are cool stars, which are very large and very bright. They are located towards the top right of the graph.
The Giants are cool stars, which are a little smaller and dimmer than the Supergiants.
The White Dwarfs are very hot stars, which are small in size and relatively dim. They are found in the lower left of the H-R Diagram.
The Main Sequence is a band of stars, which includes most of the stars, like our Sun. These are usually smaller stars, often dwarf stars.
The H-R Diagram can also show a star’s life, referred to as Stellar Evolution. During the 1930s, it was found for stars with uniform chemical composition, there is a relationship between stellar mass and the star’s luminosity and diameter.
Other important derivations of the Hertzsprung-Russell diagram can be used to show different data, for example classes of stars, protostars, brown dwarf objects, or graphs known as color index and color magnitude diagram.