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]
Nomenclature
Fomalhaut is the brightest star in the constellation of Piscis Austrinus (center).
α Piscis Austrini, or Alpha Piscis Austrini, is the system's Bayer designation. It also bears the Flamsteed designation of 24 Piscis Austrini. The classical astronomer Ptolemy included it in the constellation of Aquarius, along with the rest of Piscis Austrinus. In the 17th century, Johann Bayer firmly planted it in the primary position of Piscis Austrinus. Following Ptolemy, John Flamsteed in 1725 additionally denoted it 79 Aquarii. The current designation reflects modern consensus on Bayer's decision, that the star belongs in Piscis Austrinus.[26] Under the rules for naming objects in multiple-star systems, the three components – Fomalhaut, TW Piscis Austrini and LP 876-10 – are designated A, B and C, respectively.[27]
The star's traditional name derives from Fom al-Haut from scientific Arabic فم الحوتfam al-ḥūt (al-janūbī) "the mouth of the [Southern] Fish" (literally, "mouth of the whale"), a translation of how Ptolemy labeled it.[28][29][30]Fam in Arabic means "mouth", al "the", and ḥūt "fish"[31]
or "whale".[32]
In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[33] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[34] included a table of the first two batches of names approved by the WGSN, which included the name "Fomalhaut" for this star.
At a declination of −29.6°, Fomalhaut is located south of the celestial equator, and hence is best viewed from the Southern Hemisphere. However, its southerly declination is not as great as that of stars such as Acrux, Alpha Centauri and Canopus, meaning that, unlike them, Fomalhaut is visible from a large part of the Northern Hemisphere as well, being best seen in autumn. Its declination is greater than that of Sirius and similar to that of Antares. At 40°N, Fomalhaut rises above the horizon for eight hours and reaches only 20° above the horizon, while Capella, which rises at approximately the same time, will stay above the horizon for twenty hours. Fomalhaut can be located in northern latitudes by the fact that the western (right-hand) side of the Square of Pegasus points to it. Continuing the line from Beta to Alpha Pegasi towards the southern horizon, Fomalhaut is about 45˚[clarification needed] south of Alpha Pegasi, with no bright stars in between.[41]
Properties
Fomalhaut is a young star, for many years thought to be only 100 to 300 million years old, with a potential lifespan of a billion years.[42][43] A 2012 study gave a slightly higher age of 440±40 million years.[9] The surface temperature of the star is around 8,590 K (8,320 °C). Fomalhaut's mass is about 1.92 times that of the Sun, its luminosity is about 16.6 times greater, and its diameter is roughly 1.84 times as large.[9]
Fomalhaut is slightly metal-deficient compared to the Sun, which means it is composed of a smaller percentage of elements other than hydrogen and helium.[10] The metallicity is typically determined by measuring the abundance of iron in the photosphere relative to the abundance of hydrogen. A 1997 spectroscopic study measured a value equal to 93% of the Sun's abundance of iron.[11][nb 1] A second 1997 study deduced a value of 78%, by assuming Fomalhaut has the same metallicity as the neighboring star TW Piscis Austrini, which has since been argued to be a physical companion.[9][44] In 2004, a stellar evolutionary model of Fomalhaut yielded a metallicity of 79%.[10] Finally, in 2008, a spectroscopic measurement gave a significantly lower value of 46%.[12]
Fomalhaut has been claimed to be one of approximately 16 stars belonging to the Castor Moving Group. This is an association of stars which share a common motion through space, and have been claimed to be physically associated. Other members of this group include Castor and Vega. The moving group has an estimated age of 200±100 million years and originated from the same location.[42] More recent work has found that purported members of the Castor Moving Group appear to not only have a wide range of ages, but their velocities are too different to have been possibly associated with one another in the distant past.[22] Hence, "membership" in this dynamical group has no bearing on the age of the Fomalhaut system.[22]
The inner disk is a high-carbon small-grain (10–300 nm) ash disk, clustering at 0.1 AU from the star. Next is a disk of larger particles, with inner edge 0.4-1 AU of the star. The innermost disk is unexplained as yet.[21]
The outermost disk is at a radial distance of 133 AU (1.99×1010 km; 1.24×1010 mi), in a toroidal shape with a very sharp inner edge, all inclined 24 degrees from edge-on.[46][47] The dust is distributed in a belt about 25 AU wide. The geometric center of the disk is offset by about 15 AU (2.2×109 km; 1.4×109 mi) from Fomalhaut.[48] The disk is sometimes referred to as "Fomalhaut's Kuiper belt". Fomalhaut's dusty disk is believed to be protoplanetary,[49] and emits considerable infrared radiation. Measurements of Fomalhaut's rotation indicate that the disk is located in the star's equatorial plane, as expected from theories of star and planet formation.[50]
Herschel Space Observatory images of Fomalhaut, analysed in 2012, reveal that a large amount of fluffy micrometer-sized dust is present in the outer dust belt. Because such dust is expected to be blown out of the system by stellar radiation pressure on short timescales, its presence indicates a constant replenishment by collisions of planetesimals. The fluffy morphology of the grains suggests a cometary origin. The collision rate is estimated to be approximately 2000 kilometre-sized comets per day.[51] Observations of this outer dust ring by the Atacama Large Millimeter Array also suggested the possible existence of two planets in the system.[52] If there are additional planets from 4 to 10 AU, they must be under 20MJ; if from 2.5 outward, then 20MJ.[53]
On November 13, 2008, astronomers announced an extrasolar planet candidate, orbiting just inside the outer debris ring. This was the first extrasolar orbiting object candidate to be directly imaged in visible light, captured by the Hubble Space Telescope.[54][55] The mass of the tentative planet, Fomalhaut b, was estimated to be less than three times the mass of Jupiter, and at least the mass of Neptune. However, M-band images taken from the MMT Observatory put strong limits on the existence of gas giants within 40 AU of the star,[56] and Spitzer Space Telescope imaging suggested that the object Fomalhaut b was more likely to be a dust cloud.[57] A later 2019 synthesis of new and existing direct observations of the object confirmed that it is expanding, losing brightness, has not enough mass to detectably perturb the outer ring while crossing it, and is probably a dispersing cloud of debris from a massive planetesimal collision on a hyperbolic orbit destined to leave the Fomalhaut A system.[24] Further 2022 observations with the James Webb Space Telescope in mid-infrared failed to resolve the object in the 25.5 μmMIRI wideband filter wavelength range, reported by the same team to be consistent with the previous result.[20]
The same 2022 JWST imaging data discovered another apparent feature in the outer disk, dubbed the "Great Dust Cloud".[20] However, another team's analysis, which included other existing data, preferred its interpretation as a coincident background object, not part of the outer ring.[58] Another 2023 study detected 10 point sources around Fomalhaut; all but one of these are background objects, including the "Great Dust Cloud", but the nature of the last is unclear. It may be a background object, or a planetary companion to Fomalhaut.[59]
Fomalhaut forms a binary star with the K4-type star TW Piscis Austrini (TW PsA), which lies 0.28 parsecs (0.91 light-years) away from Fomalhaut, and its space velocity agrees with that of Fomalhaut within 0.1±0.5 km/s, consistent with being a bound companion. A recent age estimate for TW PsA (400±70 million years) agrees very well with the isochronal age for Fomalhaut (450±40 million years), further arguing for the two stars forming a physical binary.[9]
The designation TW Piscis Austrini is astronomical nomenclature for a variable star. Fomalhaut B is a flare star of the type known as a BY Draconis variable. It varies slightly in apparent magnitude, ranging from 6.44 to 6.49 over a 10.3 day period. While smaller than the Sun, it is relatively large for a flare star. Most flare stars are red M-type dwarfs.
In 2019, a team of researchers analyzing the astrometry, radial velocity measurements, and images of Fomalhaut B suggested the existence of a planet orbiting the star with a mass of 1.2+0.7 −0.6 Jupiter masses, and a poorly defined orbital period with an estimate loosely centering around 25 years.[61]
LP 876-10 is also associated with the Fomalhaut system, making it a trinary star. In October 2013, Eric Mamajek and collaborators from the RECONS consortium announced that the previously known high-proper-motion star LP 876-10 had a distance, velocity, and color-magnitude position consistent with being another member of the Fomalhaut system.[22] LP 876-10 was originally catalogued as a high-proper-motion star by Willem Luyten in his 1979 NLTT catalogue; however, a precise trigonometric parallax and radial velocity was only measured quite recently. LP 876-10 is a red dwarf of spectral type M4V, and located even farther from Fomalhaut A than TW PsA—about 5.7° away from Fomalhaut A in the sky, in the neighbouring constellation Aquarius, whereas both Fomalhaut A and TW PsA are located in constellation Piscis Austrinus. Its current separation from Fomalhaut A is about 0.77 parsecs (2.5 light-years), and it is currently located 0.987 parsecs (3.22 light-years) away from TW PsA (Fomalhaut B). LP 876-10 is located well within the tidal radius of the Fomalhaut system, which is 1.9 parsecs (6.2 light-years).[22] Although LP 876-10 is itself catalogued as a binary star in the Washington Double Star Catalog (called "WSI 138"), there was no sign of a close-in stellar companion in the imaging, spectral, or astrometric data in the Mamajek et al. study.[22] In December 2013, Kennedy et al. reported the discovery of a cold dusty debris disk associated with Fomalhaut C, using infrared images from the Herschel Space Observatory. Multiple-star systems hosting multiple debris disks are exceedingly rare.[62]
Etymology and cultural significance
Fomalhaut has had various names ascribed to it through time, and has been recognized by many cultures of the northern hemisphere, including the Arabs, Persians, and Chinese. It marked the solstice in 2500 BC. It was also a marker for the worship of Demeter in Eleusis.[63]
The Latin names are ōs piscis merīdiāni, ōs piscis merīdionālis, ōs piscis notii "the mouth of the Southern Fish".[29]
A folk name among the early Arabs was Difdi' al Awwal (الضفدع الأولal-ḍifdiʿ al-awwal) "the first frog" (the second frog is Beta Ceti).[29]
The Chinese name北落師門/北落师门 (Mandarin: Běiluòshīmén), meaning North Gate of the Military Camp, because this star is marking itself and stands alone in North Gate of the Military Campasterism, Encampment mansion (see: Chinese constellations).[64]北落师门 (Běiluòshīmén), westernized into Pi Lo Sze Mun by R.H. Allen.[29]
To the Moporr Aboriginal people of South Australia, it is a male being called Buunjill.[65] The Wardaman people of the Northern Territory called Fomalhaut Menggen —white cockatoo.[66]
^Calculation of metallicity: if m = [Fe/H], then the ratio of iron to hydrogen for Fomalhaut divided by the ratio of iron to hydrogen for the Sun is given by 10m.
^Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237: 0. Bibcode:2002yCat.2237....0D.
^ abDemory, Brice-Olivier; Ségransan, Damien; Forveille, Thierry; Queloz, Didier; Beuzit, Jean-Luc; Delfosse, Xavier; Di Folco, Emmanuel; Kervella, Pierre; Le Bouquin, Jean-Baptiste; Perrier, Christian; Benisty, Myriam; Duvert, Gilles; Hofmann, Karl-Heinz; Lopez, Bruno; Petrov, Romain (October 2009). "Mass-radius relation of low and very low-mass stars revisited with the VLTI". Astronomy and Astrophysics. 505 (1): 205–215. arXiv:0906.0602. Bibcode:2009A&A...505..205D. doi:10.1051/0004-6361/200911976. S2CID14786643.
^ abJohnson, H. L.; Iriarte, B.; Mitchell, R. I.; Wisniewskj, W. Z. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory. 4 (99): 99. Bibcode:1966CoLPL...4...99J.
^ abcdGomes da Silva, J.; Santos, N. C.; Adibekyan, V.; Sousa, S. G.; Campante, T. L.; Figueira, P.; Bossini, D.; Delgado-Mena, E.; Monteiro, M. J. P. F. G.; de Laverny, P.; Recio-Blanco, A.; Lovis, C. (1 February 2021). "Stellar chromospheric activity of 1674 FGK stars from the AMBRE-HARPS sample. I. A catalogue of homogeneous chromospheric activity". Astronomy and Astrophysics. 646: A77. arXiv:2012.10199. Bibcode:2021A&A...646A..77G. doi:10.1051/0004-6361/202039765. ISSN0004-6361. Tw piscis austrini's database entry at VizieR.
^
Bob King (1 October 2014). "Fomalhaut: A crazy-wide triple stat". Sky & Telescope. Retrieved 13 June 2020. When you next look at Fomalhaut twinkling above the fall leaves, put four fingers together and hold them up against the sky. They'll cover about 8°, or the amount of real estate spanned by the triple system.
^Couper, Heather; Henbest, Nigel (5 December 2011) [2007]. The Story of Astronomy: How the universe revealed its secrets. Hachette UK. ISBN978-1-84403-726-1. Retrieved 25 May 2024. Ptolemy [...] generally described stars by their positions in the constellation patterns: but this could get quite cumbersome, such as 'the northernmost of two stars close together over the little shield in the stern.' [...] The jewel in the constellation of Piscis Austrinus [...] is dubbed by Ptolemy as 'the mouth of the southern fish.' In Arabic, this became fam al-hut al-janub – our star Fomalhaut.
^The disc was reported by Holland, Wayne S.; et al. (1998). "Submillimetre images of dusty debris around nearby stars". Nature. 392 (6678): 788–791. Bibcode:1998Natur.392..788H. doi:10.1038/33874. S2CID4373502. They noted that the disc was centered on a cavity, which they suggested might have been swept out by planets.
^天文教育資訊網 [Astronomy Education Information Network]. Activities of Exhibition and Education in Astronomy (AEEA) (in Chinese). 7 July 2006. Archived from the original on 21 May 2011. Retrieved 24 August 2012.
^Harney, Bill Yidumduma; Cairns, Hugh C. (2004) [2003]. Dark Sparklers (revised ed.). Merimbula, New South Wales: Hugh C. Cairns. p. 204. ISBN0-9750908-0-1.
^Robinson, J.H. (September 1980). "Fomalhaut and cairn D at the Big Horn and Moose Mountain medicine wheels". Bulletin of the Astronomical Society. 12: 887. Bibcode:1980BAAS...12..887R.
Este artículo o sección necesita referencias que aparezcan en una publicación acreditada.Este aviso fue puesto el 5 de septiembre de 2011. Mapa de los calendarios utilizados por los países del mundo. En los países en que se utiliza más de un calendario se encuentran los colores de ambos calendarios en franjas. El calendario es una cuenta sistematizada del transcurso del tiempo, utilizado para la organización cronológica de actividades. Se trata de un conjunto de reglas o normas que t...
Alfred Johann Theophil Jansa von TannenauLahir16 Juli 1884Stanislawow, UkrainaMeninggal20 Desember 1963Wina, AustriaPekerjaanPerwira Angkatan Darat Austria Feldmarschalleutnant Alfred Johann Theophil Jansa von Tannenau (16 Juli 1884 di Stanislawow – 20 Desember 1963 di Wina) adalah seorang perwira Angkatan Darat Austria. Ayah Alfred Jansa adalah Emanuel Jansa, seorang kolonel di Angkatan Darat Austria-Hungaria. Ibunya adalah Anna von Meyer. Sebelum peristiwa Anschluss (ketika Austria d...
Estádio JKFull nameEstádio Municipal Juscelino KubitschekLocationItumbiara, Goiás, BrazilCoordinates18°24′31″S 49°14′37″W / 18.40861°S 49.24361°W / -18.40861; -49.24361OwnerItumbiara City HallCapacity14,445ConstructionBuilt1977OpenedOctober 12, 1977TenantsItumbiara Esporte Clube Estádio Municipal Juscelino Kubitschek, usually known as Estádio JK, is a multi-use stadium in Itumbiara, Goiás, Brazil. It is currently used mostly for football matches. The ...
У этого термина существуют и другие значения, см. Гели (значения) и Гель. Ге́ли (ед.ч. гель, от лат. gelo — «застываю») — структурированные системы, состоящие из высокомолекулярных и низкомолекулярных веществ. Наличие трёхмерного полимерного каркаса (сетки, матрицы) �...
Daryl SabaraDaryl Sabara 2007LahirDaryl Christopher SabaraPekerjaanaktorTahun aktif1995-sekarangSuami/istriMeghan Trainor (m. 2018) Daryl Christopher Sabara (lahir 14 Juni 1992) adalah seorang aktor asal Amerika Serikat. Ia berperan sebagai Juni Cortez dalam film Spy Kids (2001). Dan ia kembali berperan sebagai Juni Cortez dalam film Spy Kids 2 (2002) dan Spy Kids 3-D: Game Over (2003). Filmografi Film Tahun Film Peran Catatan 1999 Hôhokekyo tonari no Yam...
Max Stirner, sebagaimana digambarkan oleh Friedrich Engels Johann Kaspar Schmidt (25 Oktober 1806 – 26 Juni 1856), lebih dikenal dengan nama samarannya, Max Stirner, adalah seorang filsuf Jerman yang terkenal dengan teorinya tentang individualisme radikal,[1] terutama individualisme anarkis, dan sebagai salah satu pendahulu nihilisme, eksistensialisme, teori psikoanalitika, dan pascamodernisme.[2][3] Karya terpenting Stirner adalah buku berjudul Individ...
Maggiora commune di Italia Tempat Negara berdaulatItaliaRegion di ItaliaPiedmontProvinsi di ItaliaProvinsi Novara NegaraItalia Ibu kotaMaggiora PendudukTotal1.616 (2023 )GeografiLuas wilayah10,66 km² [convert: unit tak dikenal]Ketinggian397 m Berbatasan denganBoca Cureggio Valduggia Borgomanero Gargallo SejarahSanto pelindungAgapitus of Palestrina Informasi tambahanKode pos28014 Zona waktuUTC+1 UTC+2 Kode telepon0322 ID ISTAT003088 Kode kadaster ItaliaE803 Lain-lainSitus webLaman ...
ХристианствоБиблия Ветхий Завет Новый Завет Евангелие Десять заповедей Нагорная проповедь Апокрифы Бог, Троица Бог Отец Иисус Христос Святой Дух История христианства Апостолы Хронология христианства Раннее христианство Гностическое христианство Вселенские соборы Н...
2007 television miniseries For other uses, see Tin Man (disambiguation). Tin ManSci Fi Channel promotional posterGenreAdventureFantasyScience FictionWritten byJill E. BlotevogelSteven Long MitchellCraig W. Van SickleDirected byNick WillingStarringZooey DeschanelAlan CummingNeal McDonoughRaoul TrujilloKathleen RobertsonRichard DreyfussTheme music composerSimon BoswellCountry of originUnited StatesOriginal languageEnglishNo. of episodes3ProductionProducerMatthew O'ConnorCinematographyThomas Bur...
Branch of the Torricelli language family MaimaiGeographicdistributioneastern Sandaun Province, Papua New GuineaLinguistic classificationTorricelliMaimaiGlottolognucl1590The Torricelli languages as classified by Foley (2018) The Maimai languages constitute a branch of the Torricelli language family. They are spoken just to the west of Nuku town in eastern Sandaun Province, Papua New Guinea (including in Maimai Wanwan Rural LLG). Languages Maimai Beli, Laeko-Libuat Wiaki Siliput, Yahang, Heyo P...
Voce principale: Coppa Italia Dilettanti 1991-1992. Questa voce sull'argomento edizioni di competizioni calcistiche italiane è solo un abbozzo. Contribuisci a migliorarla secondo le convenzioni di Wikipedia. Coppa Italia Dilettanti(Fase Interregionale)1991-1992 Competizione Coppa Italia Dilettanti Sport Calcio Edizione 11ª Organizzatore Lega Nazionale Dilettanti Date dal 19 agosto 1991al 19 marzo 1992 Luogo Italia Partecipanti 180 Formula Gironi ed eliminazione diretta R...
Type of AC electric motor Tesla motor redirects here. For the electric car company, see Tesla, Inc. Three-phase totally-enclosed fan-cooled (TEFC) induction motor with end cover on the left, and without end cover to show cooling fan on the right. In TEFC motors, interior heat losses are dissipated indirectly through enclosure fins, mostly by forced air convection. Cutaway view through stator of TEFC induction motor, showing rotor with internal air circulation vanes. Many such motors have a sy...
المغرب: السياسة المائية الموارد المائية الموارد السطحية 15 مليار متر3 [1] الموارد الباطنية 5 ملايير متر3 [1] الموارد الكلية 20 مليار متر3 (الرتبة 114)[2] الموارد المائية نسبة الولوج إلى الماء الصالح للشرب 82% (2004) نسبة الولوج إلى شبكة المياه العادمة 76% (1996) استمرارية الماء...
State of Mexico For other uses, see Guerrero (disambiguation). You can help expand this article with text translated from the corresponding article in Spanish. (January 2023) Click [show] for important translation instructions. Machine translation, like DeepL or Google Translate, is a useful starting point for translations, but translators must revise errors as necessary and confirm that the translation is accurate, rather than simply copy-pasting machine-translated text into the English...
Public airport in Upstate New York Ogdensburg International AirportIATA: OGSICAO: KOGSFAA LID: OGSSummaryAirport typePublicOwnerOgdensburg Bridge & Port AuthorityServesOgdensburg, New York and Ottawa, OntarioLocationOswegatchie, New YorkElevation AMSL297 ft / 91 mCoordinates44°40′55″N 075°27′56″W / 44.68194°N 75.46556°W / 44.68194; -75.46556Websitewww.ogsair.comMapsFAA airport diagramRunways Direction Length Surface ft m 9/27 6,400 1,951 ...
L’ADSL (de l'anglais Asymmetric Digital Subscriber Line) est une technique de communication numérique (couche physique) de la famille xDSL. Elle permet d'utiliser une ligne téléphonique, une ligne spécialisée, ou encore une ligne RNIS (en anglais ISDN pour integrated services digital network), pour transmettre et recevoir des données numériques de manière indépendante du service téléphonique conventionnel (analogique). À ce titre, cette méthode de communication diffère de cel...
.png)
