H-R Diagrams

Hertzsprung–Russell diagram is a scatter plot of stellar luminosity or absolute magnitude versus spectral type, stellar surface temperature, or star colour. Named after the inventors Ejnar Hertzsprung and Henry Norris Russell, these are fundamental tool for presentation of the diversity of stellar types and for understanding the interrelations between the different kinds of stars. Also referred as H-R diagrams, these are widely used in astrophysics as an analysis tool in the area of stellar evolution. They are also used in estimating distances and age of star clusters.