Luminosity

Luminosity is generally understood as a measurement of brightness. Each discipline, however, defines the term differently, depending on what is being measured.

In astronomy, luminosity measures the total amount of energy emitted by a star or other astronomical object in SI units of joules per second, which are watts. A watt is one unit of power, and just as a light bulb is measured in watts, so too is the Sun, the latter having a total power output of 3.846×1026 W. It is this number which constitutes the basic metric used in astronomy and is known as 1 solar luminosity, the symbol for which is . Radiant power, however, is not the only way to conceptualize brightness, so other metrics are also used. The most common is apparent magnitude, which is the perceived brightness of an object from an observer on Earth at visible wavelengths. Other metrics are absolute magnitude, which is an object's intrinsic brightness at visible wavelengths, irrespective of distance, while bolometric magnitude is the total power output across all wavelengths.

The field of optical photometry uses a different set of distinctions, the main ones being luminance and illuminance. Astronomical photometry, by contrast, is concerned with measuring the flux, or intensity of an astronomical object's electromagnetic radiation. In the field of computer graphics the concept of luminosity is different altogether, a synonym in fact for the concept of lightness, otherwise known as the value or tone component of a color.

Read more about Luminosity:  Optical Photometry, Computer Graphics, Scattering Theory

Other articles related to "luminosity":

Super Large Hadron Collider
... The High Luminosity Large Hadron Collider (HL-LHC formerly SLHC) is a proposed upgrade to the Large Hadron Collider to be made after around ten years of ... The upgrade aims at increasing the luminosity of the machine by a factor of 10, up to 1035 cm−2s−1, providing a better chance to see rare processes and improving statistically marginal measurements ... A collection of different designs of the high luminosity interaction regions is being maintained by the European Organization for Nuclear Research (CERN) ...
Scattering Theory - Elementary Relations For Luminosity
... The following relations hold (if the target is perfectly opaque) where is the (instantaneous) luminosity ... is the integrated luminosity ...
Luminosity Function (astronomy) - Schechter Luminosity Function
... The Schechter luminosity function gives the space density of galaxies within a luminosity bin ... The form of the function is where, and is a characteristic galaxy luminosity where the power-law form of the function cuts off ... The galaxy luminosity function may have different parameters for different populations and environments it is not a universal function ...
Luminosity Function (astronomy)
... In astronomy, the luminosity function gives the number of stars or galaxies per luminosity interval ... Luminosity functions are used to study the properties of large groups or classes of objects, such as the stars in clusters or the galaxies in the ...
Super Soft X-ray Source - VY Scl Cataclysmic Variables - V751 Cyg
... V751 Cyg (BB, MW) is a VY Scl CV, has a bolometric luminosity of 6.5 x 1036 erg/s, and emits soft X-rays at quiescence ... The high luminosity (6.5 x 1036 erg/s) is particularly hard to understand in the context of VY Scl stars generally, because observations suggest that the binaries become simple red dwarf + white dwarf pairs at ... A high luminosity in soft X-rays poses an additional problem of understanding why the spectrum is of only modest excitation." The ratio He II λ4686/Hβ did not exceed ~0.5 in any of the spectra ...