Radiative flux, also known as
radiative flux density or
radiation flux, is the amount of
power radiated through a given area, in the form of
photons or other elementary particles, typically measured in W/m
2. It is used in
astronomy to determine the
magnitude and
spectral class of a star. Radiative flux also acts as a generalization of
heat flux, which is equal to the radiative flux when restricted to the
infrared spectrum.