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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 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.
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]
In astronomy, the bolometric correction is the correction made to the absolute magnitude of an object in order to convert its visible magnitude to its bolometric magnitude. It is large for stars which radiate most of their energy outside of the visible range. A uniform scale for the correction has not yet been standardized.
The monochromatic AB magnitude is defined as the logarithm of a spectral flux density with the usual scaling of astronomical magnitudes and a zero-point of about 3 631 janskys (symbol Jy), [1] where 1 Jy = 10 −26 W Hz −1 m −2 = 10 −23 erg s −1 Hz −1 cm −2 ("about" because the true definition of the zero point is based on ...
The distance modulus = is the difference between the apparent magnitude (ideally, corrected from the effects of interstellar absorption) and the absolute magnitude of an astronomical object. It is related to the luminous distance d {\displaystyle d} in parsecs by: log 10 ( d ) = 1 + μ 5 μ = 5 log 10 ( d ) − 5 {\displaystyle {\begin ...
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 ...