Hertzsprung Russell diagram
Main sequence stars
Zero-age main sequence stars
Dwarf stars
An evolutionary stage in the life of a star when it generates its energy by the conversion of hydrogen to helium via nuclear fusion in its core. Stars spend 90% of their life on the main sequence. On the Hertzsprung-Russell diagram it appears as a track running from top left (high temperature, high luminosity, high mass) to lower right (low temperature, low luminosity, low mass).
Main sequence