# Luminosity and power?

by Mafia
Tags: luminosity, power
 P: 2,179 Luminosity and power? It does have to do with power. The luminosity is the power of the radiation that the stars emit. Since a star is roughly a blackbody, the total luminosity of a star is $$L =4\pi r^2 * \sigma T^4$$ where sigma is the Stefan-Boltzmann constant. White dwarfs emit a lot of radiation per square cm of surface area because their temperature is high, but their total luminosity is low because their radius is so small.