Introduction:
Fomalhaut or Alpha Piscis Austrini (Beyer designation) is a bright main sequence star with a radius about 1.92 of the sun’. It is approximately 25 light-years from Earth and is located in the southern constellation of Piscis Austrinus. This star has captured the attention of astronomers due to its unique characteristics, particularly its debris disk and the presence of Fomalhaut b. Fomalhaut is the 18th brightest star in the night sky. Although Fomalhaut appears to be light blue to the naked eye, the true colour of the star is white.
Origin of Name and Constellation Myth and History:
Fomalhaut, (Fum al Hut), originates from Arabic (الحوت فم), which means mouth of the fish. It was named by this name due to it being present in the constellation of Piscis Austrinus which is Latin for the ‘southern fish’ and is not to be mistaken for Pisces. Fomalhaut is considered one of the Four Royal Stars that mark the seasons. Fomalhaut marks the season of autumn; therefore, it is also called the Autumn Star. It is also known for being nicknamed 'The Loneliest Star’ or ‘The Solitary One’ due to it being the only bright star in a field of faint stars. The star has taken part in a copious number of cultures and has left its mark on history. Fomalhaut was seen as a representation of the sea god Dagon in Canaanite mythology. At the winter solstice in Persia in 2582 B.C., Fomalhaut was called Hastorang, a Royal Star and one of the "four Guardians of Heaven," sentinels guarding other stars. Around 500 B.C., it was worshipped during sunrise in the Demeter temple at Eleusis.
Properties:
Coordinates: R.A= 22h 57m 39.1s, Dec = -29° 37' 20" |
Distance/ Parallax angle: 25.13 ± 0.09 ly (7.70 ± 0.03 pc) 129.81 ± 0.47 mas |
Proper Motion: RA: +328.95[2] mas/yr Dec.: −164.67[2] mas/yr |
Radial Velocity: +6.79 km/s |
Spectral type: A3V |
Surface Temperature: 8,590 K |
Mass: 3.819 × 10^30 kg |
Trinary star system: Fomalhaut forms a trinary star system with M-type, red dwarf star LP 876-10 and K-type main-sequence star TW Piscis Austrini |
Magnitude: 1.16 |
Luminosity: 16.63 L☉ |
Fomalhaut’s Debris Disks:
Fomalhaut is classified as a Vega-type star that emits extra infrared radiation. It is known to have 3 debris disks surrounding it. These disks are speculated to be caused by occasional collisions between asteroids and comets in the system. It is shaped by the gravitational forces of the unseen planets. The outermost disk with a radial distance of 133 AU and is shaped toroidally. The Debris disks are also commonly known as ‘Fomalhaut’s Kuiper Belt’. Unlike other disks, Fomalhaut’s debris disks are distinct because they are not protoplanetary disks due to the star being 440±40 million years old and the lack of gas. The presence of a debris disk around Fomalhaut indicates that there could be an exoplanet orbiting it. Certain studies suggest that there is an exoplanet called Fomalhaut b orbiting it, however, there are still debates surrounding its existence.
Life Cycle:
Fomalhaut is an A-type main sequence star, which means that it is a relatively large, hot, and luminous star expected to have a short lifespan of just a few hundred million years. It is expected to live a total of around 400-900 million years compared to the Sun's expected 10-billion-year lifespan. Due to Fomalhaut’s high mass and luminosity, it will eventually use up its hydrogen fuel relatively quickly and move off the main sequence, passing through the red giant phase before shedding its outer layers and becoming a white dwarf star



References:
European Space Agency. (2008). *Fomalhaut and Fomalhaut b*. ESA/Hubble. https://esahubble.org/images/heic0821a/
Byrd, D. (2022, October 27). *Solitary Fomalhaut guards the southern sky*. EarthSky. https://earthsky.org/brightest-stars/solitary-fomalhaut-guards-the-southern-sky/
Centre de Données astronomiques de Strasbourg. (n.d.). *Fomalhaut*. SIMBAD Astronomical Database. https://simbad.cds.unistra.fr/mobile/object.html?object_name=Fomalhaut+
NASA. (2023, May 8). *Webb looks for Fomalhaut’s asteroid belt and finds much more*. https://www.nasa.gov/missions/webb/webb-looks-for-fomalhauts-asteroid-belt-and-finds-much-more/
Webb Telescope. (2023). *Fomalhaut*. https://webbtelescope.org/contents/media/images/2023/109/01GWWHHHT27VZEQ5D1MK6EHD46
Flanders, T. (2017, October 24). *Meet Fomalhaut, the Autumn Star*. Sky & Telescope. https://skyandtelescope.org/astronomy-news/meet-fomalhaut-the-autumn-star/
Horvatin, J. (n.d.). *Brightest Stars*. Michigan State University. https://web.pa.msu.edu/people/horvatin/Astronomy_Facts/brightest_stars.html
-Authored by: Lilian Jan from The Eunolia.
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