In
astronomy,
luminosity is the amount of
energy a body radiates in unit
time.
Stellar luminosities are usually expressed in
solar luminosities, sometimes the absolute
bolometric magnitude is given instead, what is related to the luminosity.
In
X-ray and
radio wavelengths, luminosity is sometimes expressed in
watts.
In physics, luminosity is the density of luminous intensity[?] in a given direction.