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In astronomy, absolute magnitude (M) is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale; the more luminous (intrinsically bright) an object, the lower its magnitude number. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it ...
absolute magnitude A measure of a star 's absolute brightness. It is defined as the apparent magnitude the star would show if it were located at a distance of 10 parsecs, or 32.6 light-years. accretion disk A roughly circular mass of diffuse material in orbit around a central object, such as a star or black hole. The material is acquired from a ...
An illustration of light sources from magnitude 1 to 3.5, in 0.5 increments. In astronomy, magnitude is a measure of the brightness of an object, usually in a defined passband. An imprecise but systematic determination of the magnitude of objects was introduced in ancient times by Hipparchus. Magnitude values do not have a unit.
Zeta Aquarii (ζ Aquarii, ζ Aqr) is the Bayer designation for a triple star system, [7] the central star of the "water jar" asterism [9] in the equatorial constellation of Aquarius. The combined apparent visual magnitude of this system is 3.65, [ 2 ] which is readily visible to the naked eye.
The brightness usually refers the object's absolute magnitude, which, in turn, is its apparent magnitude at a distance of one astronomical unit from the Earth and Sun. The phase curve is useful for characterizing an object's regolith (soil) and atmosphere. It is also the basis for computing the geometrical albedo and the Bond albedo of the body.
For example, 3C 273 has an average apparent magnitude of 12.8 (when observing with a telescope), but an absolute magnitude of −26.7. If this object were 10 parsecs away from Earth it would appear nearly as bright in the sky as the Sun (apparent magnitude −26.744).
The absolute magnitude M, of a star or astronomical object is defined as the apparent magnitude it would have as seen from a distance of 10 parsecs (33 ly). The absolute magnitude of the Sun is 4.83 in the V band (visual), 4.68 in the Gaia satellite's G band (green) and 5.48 in the B band (blue). [20] [21] [22]
Apparent magnitude of ~12.9 Absolute magnitude: −26.7 Seemingly optically brightest APM 08279+5255: Seeming absolute magnitude of −32.2 This quasar is gravitationally lensed; its actual absolute magnitude is estimated to be −30.5 Most luminous SMSS J215728.21-360215.1: Absolute magnitude of −32.36 Highest absolute magnitude discovered ...