FOMALHAUT

'Fomalhaut' (α PsA / α Piscis Austrini / Alpha Piscis Austrini) is the brightest star in the constellation Piscis Austrinus and one of the brightest stars in the nighttime sky. Its name means "mouth of the whale", from the Arabic 'فم الحوت' ''fum al-ḥawt''. It is a class A star on the main sequence approximately 25 light-years (7.7 parsecs) from Earth.
Until about March 2000, Fomalhaut and Achernar were the two first magnitude stars furthest in angular distance from any other first magnitude star in the celestial sphere. Antares, in the constellation of Scorpius, is now the most isolated first magnitude star.
Fomalhaut is believed to be a young star, only 200 to 300 million years old, with a potential lifespan of only a billion years. The surface temperature of the star is around 8500 kelvin. Compared to the Sun, its mass is about 2.3, its luminosity is about 15, and its diameter is roughly 1.7.
It is surrounded by a disk of dust in a toroidal shape with a very sharp inner edge at a radial distance of 133 AU, inclined 24 degrees from edge-on. The dust is distributed in a belt about 25 AU wide; the geometric centre of the disk is offset by about 15 AU from Fomalhaut. The disk is sometimes referred to as "Fomalhaut's Kuiper belt".
Fomalhaut's disk is believed to be protoplanetary, and emits considerable infrared radiation. A planet has been inferred from analysis of the dust cloud in 1998.
Fomalhaut, has had various names ascribed to it through time. One such name in common use is the Lonely Star of Autumn, because it is the only first-magnitude star in the autumn sky of mid-northern latitudes. It has been recognized by many cultures of the northern hemisphere, including the Arabs, Persians and Chinese. Archaeological evidence links it to rituals dating back to about 2500 BCE. It is one of the Persians' four "royal stars". The Stregheria religion from Italy, portrays Fomalhaut as a fallen angel and quarter guardian of the northern gate.
The much-fainter flare star TW Piscis Austrini is located within a light year of Fomalhaut and the two share a common proper motion through the sky. They are believed to be companion stars and may have had a common origin in a star cluster.

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See also

★ Fomalhaut in fiction

References

# Nature 435, 1067-1070 (23 June 2005) | doi: 10.1038/nature03601

External links

★ ''Sky and Telescope'': Fomalhaut's Kuiper Belt

★ Fomalhaut

★ ALF Psa