The Hertzsprung-Russell Diagram or, the H-R Diagram for short, is a graph which plots stars according to their temperature and absolute magnitude. This graph reveals a pattern, which in fact is quite interesting. The H-R Diagram is named for the two astronomers, Ejnar Hertzsprung and Henry Russell, who discovered this pattern of stars. These two astronomers independently discovered that comparing magnitudes and spectral class color of stars yielded a lot of information about them. One key purpose of the H-R diagram is to show the relationship between temperature and absolute magnitude of stars. The type of temperature measurement used is...
white dwarfs. These stars are quite hot, around 20,000 degrees Kelvin. However, because of their small size, they are not very bright. A white dwarfs absolute magnitude is around +13.

There is some other information that the H-R diagram can give us about stars including spectral class color and luminosity. The possible colors that a star can be classified under are blue, white, yellow, orange, red, brown, and black. A black star is one that is known to be completely dead. A brown star describes a star that never reached a temperature of 18 million degrees F 10,000,255 K.