Since then, variations of the Stefan Law is widely used to determine some basic properties of a star, like:

- Star Radius
- Star Luminosity
- Star Surface temperature

To calculate any given star Luminosity, Stefan's law is expressed as:

**L = 4 π R ^{2} σ Τ ^{4}**

^{L: Luminosity (in Watts)}

^{R: Star radius}

^{T: Star's surface temperature}^{.}

^{−8}W.m

^{-2}K

^{-4}

^{This is a variation of the original Stefan's formula, widely used to calculate any star temperature by finding the absolute luminosity}

^{based in relative comparations with proper references:}

*j** = **T*^{4}

where j is the Iradiance or Flux Density (Watt/m^2), which is estimated by comparisons with references (like our Sun's Irradiance).

**Edited by rhertz, 18 June 2019 - 08:42 PM.**