Astrophysics (Index)About

Stefan-Boltzmann constant

(σ, Stefan's constant)
(relates radiation power to temperature and surface area)

The Stefan-Boltzmann constant is a physical constant relating the power radiated from a black body to its temperature according to the Stefan-Boltzmann law (i.e., Stefan-Boltzmann equation, which is not the same as the Boltzmann equation): the energy radiated by a black body is proportional to its surface and the fourth power of its temperature:

j* = σT4

In SI units, it is:

σ = 5.670374419×10-8 W m-2 K-4

It can be derived from the Boltzmann constant, Planck constant, and the speed of light. A consequence of the Stefan-Boltzmann equation: the bolometric luminosity of a black body (which approximates real astronomical objects) is j* times the surface area:

Lbol = AσT4

Further reading:

Referenced by pages:
power law
stellar radius determination
stellar structure