Noun
intrinsic brightness (plural intrinsic brightnesses)
English Wikipedia has an article on:intrinsic brightnessWikipedia
The brightness a star would have if not attenuated by distance or intervening gas or dust. As opposed to apparent brightness which it has as measured at a distance.
The intrinsic brightness of theSun is fully 5,000 times as great as if the whole surface were formed of the molten steel just issuing from the Bessemer converter. Robert Stawell Ball