page_title: Alpha Centauri
section_title: Nomenclature
hierarchical_section_title: Alpha Centauri / Nomenclature
caption_attribution_description: English: Photo of the constellation Centaurus, the Centaur
context_page_description: Alpha Centauri is the closest star system and closest planetary system to Earth's Solar System at 4.37 light-years from the Sun. It is a triple star system, consisting of three stars: α Centauri A, α Centauri B, and α Centauri C.
  Alpha Centauri A and B are Sun-like stars, and together they form the binary star Alpha Centauri AB. To the naked eye, the two main components appear to be a single star with an apparent magnitude of −0.27, the brightest star in the southern constellation of Centaurus and the third-brightest in the night sky, outshone only by Sirius and Canopus.
  Alpha Centauri A has 1.1 times the mass and 1.519 times the luminosity of the Sun, while Alpha Centauri B is smaller and cooler, at 0.907 times the Sun's mass and 0.445 times its luminosity. The pair orbit around a common centre with an orbital period of 79.91 years. Their elliptical orbit is eccentric, so that the distance between A and B varies from 35.6 AU, or about the distance between Pluto and the Sun, to 11.2 AU, or about the distance between Saturn and the Sun.
  Alpha Centauri C, or Proxima Centauri, is a small and faint red dwarf.
context_section_description: α Centauri (Latinised to Alpha Centauri) is the system's designation given by Johann Bayer in 1603. It bears the traditional name Rigil Kentaurus, which is a Latinisation of the Arabic name رِجْل القِنْطورُس‎ Rijl al-Qinṭūrus, meaning 'the Foot of the Centaur'.
  The name is frequently abbreviated to Rigil Kent or even Rigil, though the latter name is better known for Beta Orionis (Rigel).
  An alternative name found in European sources, Toliman, is an approximation of the Arabic الظَّلِيمَان‎ aẓ-Ẓalīmān (in older transcription, aṭ-Ṭhalīmān), meaning 'the (two male) Ostriches', an appellation Zakariya al-Qazwini had applied to Lambda and Mu Sagittarii, also in the southern hemisphere.
  A third name that has been applied is Bungula (/ˈbʌŋɡjuːlə/), of obscure origin. Allen can only surmise it may have been coined from the Greek letter beta (β) and Latin ungula 'hoof'.
  Alpha Centauri C was discovered in 1915 by Robert T. A. Innes, who suggested that it be named Proxima Centaurus, from Latin, meaning 'the nearest [star] of Centaurus'. The name Proxima Centauri later became more widely used and is now listed by the IAU as the approved proper name.
  In 2016, the Working Group on Star Names of the International Astronomical Union (IAU), having decided to attribute proper names to individual component stars rather than to multiple systems, approved the name Rigil Kentaurus (/ˈraɪdʒəl kɛnˈtɔːrəs/) as being restricted to Alpha Centauri A and the name Proxima Centauri (/ˈprɒksɪmə sɛnˈtɔːraɪ/) for Alpha Centauri C. 
  On 10 August 2018, the IAU approved the name Toliman (/ˈtɒlɪmæn/) for Alpha Centauri B.
caption: Alpha Centauri is the brightest object in the constellation of Centaurus (top left).
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