![]() ![]() To convert from an absolute magnitude in a specific filter band to absolute bolometric magnitude, a bolometric correction (BC) is applied. Īn object's absolute bolometric magnitude (M bol) represents its total luminosity over all wavelengths, rather than in a single filter band, as expressed on a logarithmic magnitude scale. Highly luminous objects can have negative absolute magnitudes: for example, the Milky Way galaxy has an absolute B magnitude of about −20.8. The Sun has absolute magnitude M V = +4.83. For example, a star of absolute magnitude M V = 3.0 would be 100 times as luminous as a star of absolute magnitude M V = 8.0 as measured in the V filter band. A difference of 5 magnitudes between the absolute magnitudes of two objects corresponds to a ratio of 100 in their luminosities, and a difference of n magnitudes in absolute magnitude corresponds to a luminosity ratio of 100 n/5. The more luminous an object, the smaller the numerical value of its absolute magnitude. Absolute magnitudes are denoted by a capital M, with a subscript representing the filter band used for measurement, such as M V for absolute magnitude in the V band. For Solar System bodies that shine in reflected light, a different definition of absolute magnitude (H) is used, based on a standard reference distance of one astronomical unit.Īs with all astronomical magnitudes, the absolute magnitude can be specified for different wavelength ranges corresponding to specified filter bands or passbands for stars a commonly quoted absolute magnitude is the absolute visual magnitude, which uses the visual (V) band of the spectrum (in the UBV photometric system). By hypothetically placing all objects at a standard reference distance from the observer, their luminosities can be directly compared among each other on a magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it were viewed from a distance of exactly 10 parsecs (32.6 light-years), without extinction (or dimming) of its light due to absorption by interstellar matter and cosmic dust. For the science fiction magazine, see Absolute Magnitude (magazine).Ībsolute magnitude ( M) is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale. This article is about the brightness of stars. ![]()
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