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Luminosity is the measurement of brightness. Depending on the field of study, luminosity is defined differently depending on what is being measured. In astronomy, luminosity measures the total amount of energy emitted by a star or other astronomical object per unit time.  Luminosity is an intrinsic measurable property of a star independent of distance. The concept of magnitude however incorporates distance.

The Stefan-Boltzmann equation applied to a black body gives the value for luminosity for a black body. The equation for this is

L = σAT4


A is the area

σ is the Stefan-Boltzmann constant of 5.67 x 108 W m-2K-4

For a point source of light of luminosity L that radiated equally in all directions the equation is as follows:

F = L/A


A is the area of the illuminated surface

F is the flux density of the illuminated surface

In scattering theory and acceleratory physics, luminosity is the number of particles per unit area per unit time multiplied by the opacity of the target. It is important to characterize the performance of an accelerator.