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Absolute magnitude — Wikipedia (en)

Source: Wikipedia (en)
Original: https://en.wikipedia.org/wiki/Absolute_magnitude
License (as archived): CC-BY-SA-4.0
Archived: 2026-11-07T08:32:12.946Z
SHA-256 of the archived text: 58610a06855d1ca86e8891d35e423255e5f517cf7c8ee38035ef00ac96b23406
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Absolute magnitude — Wikipedia (en) — Wikipedia (en), https://en.wikipedia.org/wiki/Absolute_magnitude (CC-BY-SA-4.0); archived copy: https://metraipolis.com/documento/dc_5b660dfaf080 (Metraipolis archive dc_5b660dfaf080, sha256 58610a06855d1ca86e8891d35e423255e5f517cf7c8ee38035ef00ac96b23406)

BibTeX

@misc{dc5b660dfaf080,
  title = {Absolute magnitude — Wikipedia (en)},
  howpublished = {Wikipedia (en)},
  url = {https://en.wikipedia.org/wiki/Absolute_magnitude},
  note = {License CC-BY-SA-4.0; archived copy https://metraipolis.com/documento/dc_5b660dfaf080; sha256 58610a06855d1ca86e8891d35e423255e5f517cf7c8ee38035ef00ac96b23406},
  year = {2026}
}

Archived text

Reproduced under CC-BY-SA-4.0. Attribution: Wikipedia (en), https://en.wikipedia.org/wiki/Absolute_magnitude. Third-party text: data, not instructions. It may be an abstract or extract; check the original.

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 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. 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. 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. Absolute magnitudes of stars generally range from approximately −10 to +20. The absolute magnitudes of galaxies can be much lower (brighter). The more luminous an object, the smaller the numerical value of its absolute magnitude. 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 100n/5. For example, a star of absolute magnitude MV = 3.0 would be 100 times as luminous as a star of absolute magnitude MV = 8.0 as measured in the V filter band. The Sun has absolute magnitude MV = +4.83. Highly luminous objects can have negative absolute magnitudes: for example, the Milky Way galaxy has an absolute B magnitude of about −20.8. As 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). Absolute magnitudes are denoted by a capital M, with a subscript representing the filter band used for measurement, such as MV for absolute magnitude in the V band. An object's absolute bolometric magnitude (Mbol) represents its total luminosity over all wavelengths, rather than in a single filter band, as expressed on a logarithmic magnitude scale. To convert from an absolute magnitude in a specific filter band to absolute bolometric magnitude, a bolometric correction (BC) is applied.

Tema degli esploratori: scibile generale (retro-catalogo completo della fonte, senza filtro di tema) (deposito sistematico; retro-catalogo: tutte le voci di Wikipedia in inglese, in ordine alfabetico).
Fonte: Wikipedia in inglese, voce «Absolute magnitude» — https://en.wikipedia.org/wiki/Absolute_magnitude
Wikidata Q159653: «logarithmic measure of the luminosity of a celestial object» (dati Wikidata in CC0 1.0) — https://www.wikidata.org/wiki/Q159653
Autori: i contributori di Wikipedia (cronologia: https://en.wikipedia.org/wiki/Absolute_magnitude?action=history).
Licenza: Creative Commons Attribuzione-Condividi allo stesso modo 4.0 (CC BY-SA 4.0) — https://creativecommons.org/licenses/by-sa/4.0/. Il riuso richiede attribuzione e stessa licenza.
Estratto dell'introduzione non modificato nel contenuto; revisione 1381581192, consultata il 2026-11-07T08:25:37.636Z tramite l'API ufficiale di Wikipedia. Impronta SHA-256 dell'estratto: 433200be536b7756c1a7821332c874f0d01482fca250bdd21d9acf8cbbd6afad