Fomalhaut

Fomalhaut
	; DSS image of Fomalhaut, field of view 2.7×2.9 degrees.; Credit NASA, ESA, and the Digitized Sky Survey 2. Acknowledgment: Davide De Martin (ESA/Hubble)
Observation data; Epoch J2000 Equinox J2000
Constellation	Piscis Austrinus (Fomalhaut A+B), Aquarius (Fomalhaut C)
Pronunciation	/ˈfoʊməl.hɔːt/, /foʊməlˈhɔːt/
	Fomalhaut
Right ascension	22h 57m 39.0465s
Declination	−29° 37′ 20.050″
Apparent magnitude (V)	1.16
	TW Piscis Austrini
Right ascension	22h 56m 24.05256s
Declination	−31° 33′ 56.0306″
Apparent magnitude (V)	6.48
	LP 876-10
Right ascension	22h 48m 04.47s
Declination	−24° 22′ 07.5″
Apparent magnitude (V)	12.618
Characteristics
Spectral type	A3 V / K5Vp / M4V
U−B color index	0.08 / 1.02 / ?
B−V color index	0.09 / 1.10 / 1.683
Variable type	None / BY Draconis / ?
Astrometry
Fomalhaut
Proper motion (μ)	RA: +328.95 mas/yr ; Dec.: −164.67 mas/yr
Parallax (π)	129.81 ± 0.47 mas
Distance	25.13 ± 0.09 ly ; (7.70 ± 0.03 pc)
Absolute magnitude (MV)	1.72
TW Piscis Austrini
Radial velocity (Rv)	+6.79 km/s
Proper motion (μ)	RA: +330.203 mas/yr ; Dec.: −158.98 mas/yr
Parallax (π)	131.5525 ± 0.0275 mas
Distance	24.793 ± 0.005 ly ; (7.602 ± 0.002 pc)
Absolute magnitude (MV)	7.08
Details
Fomalhaut
Mass	1.92±0.02 M☉
Radius	1.842±0.019 R☉
Luminosity	16.63±0.48 L☉
Surface gravity (log g)	4.21 cgs
Temperature	8,590 K
Metallicity [Fe/H]	−0.03 to −0.34 dex
Rotational velocity (v sin i)	93 km/s
Age	440±40 Myr
TW Piscis Austrini
Mass	0.704±0.016 M☉
Radius	0.658±0.009 R☉
Luminosity	0.19 L☉
Temperature	4,610±67 K
Metallicity [Fe/H]	−0.07±0.03 dex
Rotation	10.3 days
Rotational velocity (v sin i)	2.93 km/s
Age	440 Myr
Other designations
	Fomalhaut: α Piscis Austrini, α PsA, Alpha PsA, 24 Piscis Austrini, CPD−30°685, FK5 867, GJ 881, HD 216956, HIP 113368, HR 8728, SAO 191524
	TW Piscis Austrini: Fomalhaut B, TW PsA, CD−32°17321, CPD−32°6550, GJ 879, HD 216803, HIP 113283, HR 8721, SAO 214197, LTT 9283
	LP 876-10: Fomalhaut C, NLTT 54872, GSC 06964-01226, 2MASS J22480446-2422075
Database references
SIMBAD	AC
	AB
	A (Fomalhaut)
	B (TW PsA)
	C (LP 876-10)
	planet b
Exoplanet Archive	data
ARICNS	A (Fomalhaut)
	B (TW PsA)
	A B C Location of Fomalhaut A, B, C;

Fomalhaut (UK: /ˈfɒməloʊt/, US: /ˈfoʊməlhɔːt/^[16]) is the brightest star in the southern constellation of Piscis Austrinus, the Southern Fish, and one of the brightest stars in the night sky. It has the Bayer designation Alpha Piscis Austrini, which is an alternative form of α Piscis Austrini, and is abbreviated Alpha PsA or α PsA. This is a class A star on the main sequence approximately 25 light-years (7.7 pc) from the Sun as measured by the Hipparcos astrometry satellite.^[17] Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.^[18]

It is classified as a Vega-like star that emits excess infrared radiation,^[19]^[20] indicating it is surrounded by a circumstellar disk.^[21] Fomalhaut, K-type main-sequence star TW Piscis Austrini, and M-type, red dwarf star LP 876-10 constitute a triple system, even though the companions are separated by approximately 8 degrees.^[22]^[23]

Fomalhaut was the first stellar system with an extrasolar planet candidate imaged at visible wavelengths, designated Fomalhaut b. However, analyses in 2019 and 2023 of existing and new observations indicate that Fomalhaut b is not a planet, but rather an expanding region of debris from a massive planetesimal collision.^[24]^[25]^[20]

^ "Fomalhaut". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
^ ^a ^b ^c ^d ^e Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).
^ Cite error: The named reference ducati was invoked but never defined (see the help page).
^ ^a ^b ^c ^d ^e ^f Cite error: The named reference Gaia3 was invoked but never defined (see the help page).
^ Cite error: The named reference hojjatpanah2019 was invoked but never defined (see the help page).
^ ^a ^b ^c ^d ^e Cite error: The named reference SIMBAD-fomC was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference aaa505_1_205 was invoked but never defined (see the help page).
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^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Cite error: The named reference age_mam was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference aaa426 was invoked but never defined (see the help page).
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^ ^a ^b ^c ^d Cite error: The named reference Gomes2021 was invoked but never defined (see the help page).
^ Cite error: The named reference Mamajek was invoked but never defined (see the help page).
^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
^ Wells, John C. (2008). Longman Pronunciation Dictionary (3rd ed.). Longman. ISBN 978-1-4058-8118-0.
^ Cite error: The named reference GSM was invoked but never defined (see the help page).
^ Cite error: The named reference baas25_1319 was invoked but never defined (see the help page).
^ Andrews, Robin George (8 May 2023). "Webb Telescope Finds a Star Cloaked in 3 Rings of Ruined Worlds - Astronomers have gained a new understanding of the chaos that wreathes the bright star Fomalhaut with the help of the powerful space observatory". The New York Times. Archived from the original on 8 May 2023. Retrieved 8 May 2023.
^ ^a ^b Cite error: The named reference Gaspar2023 was invoked but never defined (see the help page).
^ Cite error: The named reference vegalikedisc was invoked but never defined (see the help page).
^ Cite error: The named reference Mamajek2013 was invoked but never defined (see the help page).
^ Cite error: The named reference skyandtelescope2014-10-01 was invoked but never defined (see the help page).
^ Cite error: The named reference gaspar20newhst was invoked but never defined (see the help page).
^ Andreoli, Claire (20 April 2020). "Exoplanet Apparently Disappears in Latest Hubble Observations". NASA. Retrieved 21 April 2020.

[1] "Fomalhaut". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)

[aaa474_2_653-2] Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).

[ducati-3] Cite error: The named reference ducati was invoked but never defined (see the help page).

[Gaia3-4] ^ ^a ^b ^c ^d ^e ^f Cite error: The named reference Gaia3 was invoked but never defined (see the help page).

[hojjatpanah2019-5] Cite error: The named reference hojjatpanah2019 was invoked but never defined (see the help page).

[SIMBAD-fomC-6] Cite error: The named reference SIMBAD-fomC was invoked but never defined (see the help page).

[aaa505_1_205-7] Cite error: The named reference aaa505_1_205 was invoked but never defined (see the help page).

[clpl4-8] Cite error: The named reference clpl4 was invoked but never defined (see the help page).

[age_mam-9] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Cite error: The named reference age_mam was invoked but never defined (see the help page).

[aaa426-10] Cite error: The named reference aaa426 was invoked but never defined (see the help page).

[mnras286_3-11] Cite error: The named reference mnras286_3 was invoked but never defined (see the help page).

[aaa490_1-12] Cite error: The named reference aaa490_1 was invoked but never defined (see the help page).

[Gomes2021-13] Cite error: The named reference Gomes2021 was invoked but never defined (see the help page).

[Mamajek-14] Cite error: The named reference Mamajek was invoked but never defined (see the help page).

[SIMBAD-15] Cite error: The named reference SIMBAD was invoked but never defined (see the help page).

[16] Wells, John C. (2008). Longman Pronunciation Dictionary (3rd ed.). Longman. ISBN 978-1-4058-8118-0.

[GSM-17] Cite error: The named reference GSM was invoked but never defined (see the help page).

[baas25_1319-18] Cite error: The named reference baas25_1319 was invoked but never defined (see the help page).

[NYT-20230508-19] Andrews, Robin George (8 May 2023). "Webb Telescope Finds a Star Cloaked in 3 Rings of Ruined Worlds - Astronomers have gained a new understanding of the chaos that wreathes the bright star Fomalhaut with the help of the powerful space observatory". The New York Times. Archived from the original on 8 May 2023. Retrieved 8 May 2023.

[Gaspar2023-20] Cite error: The named reference Gaspar2023 was invoked but never defined (see the help page).

[vegalikedisc-21] Cite error: The named reference vegalikedisc was invoked but never defined (see the help page).

[Mamajek2013-22] Cite error: The named reference Mamajek2013 was invoked but never defined (see the help page).

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[gaspar20newhst-24] Cite error: The named reference gaspar20newhst was invoked but never defined (see the help page).

[25] Andreoli, Claire (20 April 2020). "Exoplanet Apparently Disappears in Latest Hubble Observations". NASA. Retrieved 21 April 2020.

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Observation data Epoch J2000 Equinox J2000
DSS image of Fomalhaut, field of view 2.7×2.9 degrees. Credit NASA, ESA, and the Digitized Sky Survey 2. Acknowledgment: Davide De Martin (ESA/Hubble)
Constellation	Piscis Austrinus (Fomalhaut A+B), Aquarius (Fomalhaut C)
Pronunciation	/ˈfoʊməl.hɔːt/,^[1] /foʊməlˈhɔːt/
Fomalhaut
Right ascension	22^h 57^m 39.0465^s^[2]
Declination	−29° 37′ 20.050″^[2]
Apparent magnitude (V)	1.16^[3]
TW Piscis Austrini
Right ascension	22^h 56^m 24.05256^s^[4]
Declination	−31° 33′ 56.0306″^[4]
Apparent magnitude (V)	6.48^[5]
LP 876-10
Right ascension	22^h 48^m 04.47^s^[6]
Declination	−24° 22′ 07.5″^[6]
Apparent magnitude (V)	12.618^[6]
Characteristics
Spectral type	A3 V / K5Vp / M4V^[6]^[7]
U−B color index	0.08 / 1.02 / ?^[8]
B−V color index	0.09 / 1.10 / 1.683^[6]^[8]
Variable type	None / BY Draconis / ?
Astrometry
Fomalhaut
Proper motion (μ)	RA: +328.95^[2] mas/yr Dec.: −164.67^[2] mas/yr
Parallax (π)	129.81 ± 0.47 mas^[2]
Distance	25.13 ± 0.09 ly (7.70 ± 0.03 pc)
Absolute magnitude (M_V)	1.72^[9]
TW Piscis Austrini
Radial velocity (R_v)	+6.79^[4] km/s
Proper motion (μ)	RA: +330.203^[4] mas/yr Dec.: −158.98^[4] mas/yr
Parallax (π)	131.5525 ± 0.0275 mas^[4]
Distance	24.793 ± 0.005 ly (7.602 ± 0.002 pc)
Absolute magnitude (M_V)	7.08^[9]
Details
Fomalhaut
Mass	1.92±0.02^[9] `M`_☉
Radius	1.842±0.019^[9] `R`_☉
Luminosity	16.63±0.48^[9] `L`_☉
Surface gravity (log g)	4.21^[10] cgs
Temperature	8,590^[9] K
Metallicity [Fe/H]	−0.03^[11] to −0.34^[12] dex
Rotational velocity (v sin i)	93^[10] km/s
Age	440±40^[9] Myr
TW Piscis Austrini
Mass	0.704±0.016^[13] `M`_☉
Radius	0.658±0.009^[13] `R`_☉
Luminosity	0.19^[9] `L`_☉
Temperature	4,610±67^[13] K
Metallicity [Fe/H]	−0.07±0.03^[13] dex
Rotation	10.3^[14] days
Rotational velocity (v sin i)	2.93^[7] km/s
Age	440^[9] Myr
Other designations

Fomalhaut: α Piscis Austrini, α PsA, Alpha PsA, 24 Piscis Austrini, CPD−30°685, FK5 867, GJ 881, HD 216956, HIP 113368, HR 8728, SAO 191524^[15]
TW Piscis Austrini: Fomalhaut B, TW PsA, CD−32°17321, CPD−32°6550, GJ 879, HD 216803, HIP 113283, HR 8721, SAO 214197, LTT 9283
LP 876-10: Fomalhaut C, NLTT 54872, GSC 06964-01226, 2MASS J22480446-2422075
Database references
SIMBAD	AC
	AB
	A (Fomalhaut)
	B (TW PsA)
	C (LP 876-10)
	planet b
Exoplanet Archive	data
ARICNS	A (Fomalhaut)
	B (TW PsA)
A B C Location of Fomalhaut A, B, C