Absolute Brightness
The total luminosity radiated by an object.
Absolute Luminosity ...
Absolute Brightness (Absolute Magnitude)
A measure of the true brightness of an object. The absolute brightness or magnitude of an object is the apparent brightness or magnitude it would have if it were located exactly 32.
absolute brightness The apparent brightness a star would have if it were placed at a standard distance of 10 parsecs from Earth.
The absolute brightness of a star is equivalent to its luminosity. The apparent brightness of a star is the rate at which energy from the star reaches unit area of a detector.
Absolute brightness. The total energy radiated into space, per second, by a celestial object such as a star.
Lunation.
The period between successive New Moons.
M
Magnetosphere.
Deeply important, because their absolute brightnesses are tied to their variation periods, Cepheids are our keys to finding the distances of galaxies and to defining the expansion properties of the Universe.
novae: the absolute brightness is related to the decay rate of the brightness. This allows distances to be found for nearby galaxies.O stars: all O stars have roughly the same brightnesses, so the distances to nearby galaxies can be determined.
Relatively rare among this subclass are the Cepheid variables; these yellow supergiant stars are historically important because, having periods roughly proportional to their absolute brightness, ...
Further methods, mostly of the standard candle variety, are the variable stars called Cepheids — the absolute brightness of which depends on their observed period of variation —, supernova brightnesses, ...
(d) Total radiant energy output per second (absolute brightness, usually expressed in ergs s-1 or in magnitudes). L = 4R2T4 see Stefan's Law [H76] ...
Both the apparent and absolute brightness of objects in space will be different at different wavelengths, for example the infrared magnitude will not be the same as a visible light magnitude, however, the above formula still applies.
standard candle
An object for which the absolute brightness can be determined and then used to determine distance.
star
A massive ball of gas which produces its own energy by means of nuclear fusion occurring within its core.
PERIOD-LUMINOSITY RELATION - Relation between the pulsation period of a variable star and its absolute brightness. Measurement of the pulsation period allows the distance of the star to be determined.
Hubble used triangulation on nearby Cepheids, and correlated the Cepheid's period to their absolute brightness. Then by measuring the period and brightness of Cepheids in nebulae, he established their distance by their brightness.
Kapteyn finds that magnitude for magnitude, the absolute brightness of the solar stars is only one-fifth of that of the Sirian stars, so that in the mean they must be at less than half the distance.
But this technique also requires good calibration using parallax and Cepheids. Without knowing the precise distances to a few supernovae, there is no way to determine their absolute brightness, so the technique would not work.
 See also: Absolute, Distance, Light, Star, Solar
  
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