👉 Luminosity, in physics and astronomy, refers to the amount of energy or light that is emitted by a celestial object such as a star. It is measured in units of erg (e-4J) per second squared, where "e" represents Euler's number, approximately 2.71828. The luminosity of a star is proportional to its mass and radius, with the luminosity of a star being directly proportional to the square root of its mass and radius.