a plot of stars that shows their relative brightness and temperature; first developed by Enjar Hertzsprung and Henry Norris Russell.
A plot of luminosity versus temperature for a group of stars that can be used to classify the evolutionary state of stars.
A plot of the intrinsic brightness versus the surface temperature of the stars. It separates the effects of temperature and surface area versus spectral type, but also luminosity versus surface temperature or color.
The H-R (Hertzsprung-Russell) diagram is used by astronomers to classify stars according to their luminosity, spectral type, color, temperature and evolutionary stage. Most stars fall into the Main Sequence, which runs from upper left to lower right.
The Hertzsprung -Russell (H-R) Diagram is a graph that plots stars color (spectral type or surface temperature) vs. its luminosity (intrinsic brightness or absolute magnitude). On it, astronomers plot stars' color, temperature, luminosity, spectral type, and evolutionary stage. This diagram shows that there are 3 very different types of stars: Most stars, including the sun, are "main sequence stars," fueled by nuclear fusion converting hydrogen into helium. For these stars, the hotter they are, the brighter. Giants and Supergiants are above the main sequence. Faint white dwarfs (hot, dim stars) are below the main sequence stars.