Altair: Difference between revisions

Altair
	Location of Altair (circled)
Observation data; Epoch J2000.097 Equinox J2000.0 (ICRS)
Constellation	Aquila
Pronunciation	/ˈæltɛər/, /ˈæltaɪər/
Right ascension	19h 50m 46.99855s
Declination	+08° 52′ 05.9563″
Apparent magnitude (V)	0.76
Characteristics
Evolutionary stage	Main sequence
Spectral type	A7Vn
U−B color index	+0.09
B−V color index	+0.22
V−R color index	+0.14
R−I color index	+0.13
Variable type	Delta Scuti
Astrometry
Radial velocity (Rv)	−26.1±0.9 km/s
Proper motion (μ)	RA: +536.23 mas/yr ; Dec.: +385.29 mas/yr
Parallax (π)	194.95 ± 0.57 mas
Distance	16.73 ± 0.05 ly ; (5.13 ± 0.01 pc)
Absolute magnitude (MV)	2.22
Details
Mass	1.86±0.03 M☉
Radius	1.57 – 2.01 R☉
Luminosity	10.6 L☉
Surface gravity (log g)	4.29 cgs
Temperature	6,860 – 8,621 K
Metallicity [Fe/H]	−0.2 dex
Rotation	7.77 hours
Rotational velocity (v sin i)	242 km/s
Age	100 Myr
Other designations
	Atair, α Aquilae, α Aql, Alpha Aquilae, Alpha Aql, 53 Aquilae, 53 Aql, BD+08°4236, FK5 745, GJ 768, HD 187642, HIP 97649, HR 7557, SAO 125122, WDS 19508+0852A, LFT 1499, LHS 3490, LTT 15795, NLTT 48314
Database references
SIMBAD	data

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Latest revision as of 04:00, 23 January 2024

Altair is the brightest star in the constellation of Aquila and the twelfth-brightest star in the night sky. It has the Bayer designation Alpha Aquilae, which is Latinised from α Aquilae and abbreviated Alpha Aql or α Aql. Altair is an A-type main-sequence star with an apparent visual magnitude of 0.77 and is one of the vertices of the Summer Triangle asterism; the other two vertices are marked by Deneb and Vega.^[7]^[14]^[15] It is located at a distance of 16.7 light-years (5.1 parsecs) from the Sun.^[16]^: 194 Altair is currently in the G-cloud—a nearby interstellar cloud, an accumulation of gas and dust.^[17]^[18]

Altair rotates rapidly, with a velocity at the equator of approximately 286 km/s.^{[nb 2]}^[11] This is a significant fraction of the star's estimated breakup speed of 400 km/s.^[19] A study with the Palomar Testbed Interferometer revealed that Altair is not spherical, but is flattened at the poles due to its high rate of rotation.^[20] Other interferometric studies with multiple telescopes, operating in the infrared, have imaged and confirmed this phenomenon.^[11]

Nomenclature

Altair is the brightest star in the constellation Aquila.

α Aquilae (Latinised to Alpha Aquilae) is the star's Bayer designation. The traditional name Altair has been used since medieval times. It is an abbreviation of the Arabic phrase النسر الطائر Al-Nisr Al-Ṭa'ir, "the flying eagle".^[21]

In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)^[22] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016^[23] included a table of the first two batches of names approved by the WGSN, which included Altair for this star. It is now so entered in the IAU Catalog of Star Names.^[24]

Physical characteristics

Along with β Aquilae and γ Aquilae, Altair forms the well-known line of stars sometimes referred to as the Family of Aquila or Shaft of Aquila.^[16]^: 190

Altair is a type-A main-sequence star with about 1.8 times the mass of the Sun and 11 times its luminosity.^[11]^[9] It is thought to be a young star close to the zero age main sequence at about 100 million years old, although previous estimates gave an age closer to one billion years old.^[8] Altair rotates rapidly, with a rotational period of under eight hours;^[8] for comparison, the equator of the Sun makes a complete rotation in a little more than 25 days, but Altair's rotation is similar to, and slightly faster than, those of Jupiter and Saturn. Like those two planets, its rapid rotation causes the star to be oblate; its equatorial diameter is over 20 percent greater than its polar diameter.^[11]

A light curve for Altair, adapted from Buzasi *et al.* (2005)^[6]

Satellite measurements made in 1999 with the Wide Field Infrared Explorer showed that the brightness of Altair fluctuates slightly, varying by just a few thousandths of a magnitude with several different periods less than 2 hours.^[6] As a result, it was identified in 2005 as a Delta Scuti variable star. Its light curve can be approximated by adding together a number of sine waves, with periods that range between 0.8 and 1.5 hours.^[6] It is a weak source of coronal X-ray emission, with the most active sources of emission being located near the star's equator. This activity may be due to convection cells forming at the cooler equator.^[19]

Rotational effects

The angular diameter of Altair was measured interferometrically by R. Hanbury Brown and his co-workers at Narrabri Observatory in the 1960s. They found a diameter of 3 milliarcseconds.^[25] Although Hanbury Brown et al. realized that Altair would be rotationally flattened, they had insufficient data to experimentally observe its oblateness. Later, using infrared interferometric measurements made by the Palomar Testbed Interferometer in 1999 and 2000, Altair was found to be flattened. This work was published by G. T. van Belle, David R. Ciardi and their co-authors in 2001.^[20]

Theory predicts that, owing to Altair's rapid rotation, its surface gravity and effective temperature should be lower at the equator, making the equator less luminous than the poles. This phenomenon, known as gravity darkening or the von Zeipel effect, was confirmed for Altair by measurements made by the Navy Precision Optical Interferometer in 2001, and analyzed by Ohishi et al. (2004) and Peterson et al. (2006).^[9]^[26] Also, A. Domiciano de Souza et al. (2005) verified gravity darkening using the measurements made by the Palomar and Navy interferometers, together with new measurements made by the VINCI instrument at the VLTI.^[27]

Altair is one of the few stars for which a direct image has been obtained.^[28] In 2006 and 2007, J. D. Monnier and his coworkers produced an image of Altair's surface from 2006 infrared observations made with the MIRC instrument on the CHARA array interferometer; this was the first time the surface of any main-sequence star, apart from the Sun, had been imaged.^[28] The false-color image was published in 2007. The equatorial radius of the star was estimated to be 2.03 solar radii, and the polar radius 1.63 solar radii—a 25% increase of the stellar radius from pole to equator.^[11] The polar axis is inclined by about 60° to the line of sight from the Earth.^[19]

Etymology, mythology and culture

The term Al Nesr Al Tair appeared in Al Achsasi al Mouakket's catalogue, which was translated into Latin as Vultur Volans.^[29] This name was applied by the Arabs to the asterism of Altair, β Aquilae and γ Aquilae and probably goes back to the ancient Babylonians and Sumerians, who called Altair "the eagle star".^[2]^: 17–18 The spelling Atair has also been used.^[30] Medieval astrolabes of England and Western Europe depicted Altair and Vega as birds.^[31]

The Koori people of Victoria also knew Altair as Bunjil, the wedge-tailed eagle, and β and γ Aquilae are his two wives the black swans. The people of the Murray River knew the star as Totyerguil.^[32]^: 4 The Murray River was formed when Totyerguil the hunter speared Otjout, a giant Murray cod, who, when wounded, churned a channel across southern Australia before entering the sky as the constellation Delphinus.^[32]^: 115

In Chinese belief, the asterism consisting of Altair, β Aquilae and γ Aquilae is known as Hé Gǔ (河鼓; lit. "river drum").^[30] The Chinese name for Altair is thus Hé Gǔ èr (河鼓二; lit. "river drum two", meaning the "second star of the drum at the river").^[33] However, Altair is better known by its other names: Qiān Niú Xīng (牵牛星 / 牽牛星) or Niú Láng Xīng (牛郎星), translated as the cowherd star.^[34]^[35] These names are an allusion to a love story, The Cowherd and the Weaver Girl, in which Niulang (represented by Altair) and his two children (represented by β Aquilae and γ Aquilae) are separated from respectively their wife and mother Zhinu (represented by Vega) by the Milky Way. They are only permitted to meet once a year, when magpies form a bridge to allow them to cross the Milky Way.^[35]^[36]

The people of Micronesia called Altair Mai-lapa, meaning "big/old breadfruit", while the Māori people called this star Poutu-te-rangi, meaning "pillar of heaven".^[37]

In Western astrology, the star was ill-omened, portending danger from reptiles.^[30]

This star is one of the asterisms used by Bugis sailors for navigation, called bintoéng timoro, meaning "eastern star".^[38]

A group of Japanese scientists sent a radio signal to Altair in 1983 with the hopes of contacting extraterrestrial life.^[39]

NASA announced Altair as the name of the Lunar Surface Access Module (LSAM) on December 13, 2007.^[40] The Russian-made Beriev Be-200 Altair seaplane is also named after the star.^[41]

Visual companions

The bright primary star has the multiple star designation WDS 19508+0852A and has several faint visual companion stars, WDS 19508+0852B, C, D, E, F and G.^[13] All are much more distant than Altair and not physically associated.^[42]

Multiple/double star designation: WDS 19508+0852^[13]
Component	Primäre	Right ascension (α) Equinox J2000.0	Declination (δ) Equinox J2000.0	Epoch of observed separation	Angular distance from primary	Position angle (relative to primary)	Apparent magnitude (V)	Database reference
B	A	19^h 50^m 40.5^s	+08° 52′ 13″^[43]	2015	195.8″	286°	9.8	SIMBAD
C	A	19^h 51^m 00.8^s	+08° 50′ 58″^[44]	2015	186.4″	110°	10.3	SIMBAD
D	A			2015	26.8″	105°	11.9
E	A			2015	157.3″	354°	11.0
F	A	19^h 51^m 02.0^s	+08° 55′ 33″	2015	292.4″	48°	10.3	SIMBAD
G	A			2015	185.1″	121°	13.0

Notes

^ ^a ^b Owing to its rapid rotation, Altair's radius is larger at its equator than at its poles; it is also cooler at the equator than at the poles.
^ From values of v sin i and i in the second column of Table 1, Monnier et al. 2007.

References

^ "Altair: definition of Altair in Oxford dictionary (American English)". Archived from the original on May 12, 2014.
^ ^a ^b Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
^ ^a ^b ^c ^d ^e van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600
^ ^a ^b ^c ^d ^e 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.
^ Gray, R. O.; et al. (2003), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I", The Astronomical Journal, 126 (4): 2048, arXiv:astro-ph/0308182, Bibcode:2003AJ....126.2048G, doi:10.1086/378365, S2CID 119417105.
^ ^a ^b ^c ^d ^e Buzasi, D. L.; Bruntt, H.; Bedding, T. R.; Retter, A.; Kjeldsen, H.; Preston, H. L.; Mandeville, W. J.; Suarez, J. C.; Catanzarite, J. (February 2005). "Altair: The Brightest δ Scuti Star". The Astrophysical Journal. 619 (2): 1072–1076. arXiv:astro-ph/0405127. Bibcode:2005ApJ...619.1072B. doi:10.1086/426704. ISSN 0004-637X. S2CID 16524681.
^ ^a ^b ^c NAME ALTAIR -- Variable Star of delta Sct type, database entry, SIMBAD. Accessed on line November 25, 2008.
^ ^a ^b ^c ^d ^e ^f ^g Bouchaud, K.; Domiciano De Souza, A.; Rieutord, M.; Reese, D. R.; Kervella, P. (2020). "A realistic two-dimensional model of Altair". Astronomy and Astrophysics. 633: A78. arXiv:1912.03138. Bibcode:2020A&A...633A..78B. doi:10.1051/0004-6361/201936830. S2CID 208857428.
^ ^a ^b ^c ^d Peterson, D. M.; Hummel, C. A.; Pauls, T. A.; et al. (2006). "Resolving the Effects of Rotation in Altair with Long-Baseline Interferometry". The Astrophysical Journal. 636 (2): 1087–1097. arXiv:astro-ph/0509236. Bibcode:2006ApJ...636.1087P. doi:10.1086/497981. S2CID 18683397. See Table 2 for stellar parameters.
^ Malagnini, M. L.; Morossi, C. (November 1990), "Accurate absolute luminosities, effective temperatures, radii, masses and surface gravities for a selected sample of field stars", Astronomy and Astrophysics Supplement Series, 85 (3): 1015–1019, Bibcode:1990A&AS...85.1015M
^ ^a ^b ^c ^d ^e ^f Monnier, J. D.; Zhao, M; Pedretti, E; Thureau, N; Ireland, M; Muirhead, P; Berger, J. P.; Millan-Gabet, R; Van Belle, G; Ten Brummelaar, T; McAlister, H; Ridgway, S; Turner, N; Sturmann, L; Sturmann, J; Berger, D (2007). "Imaging the surface of Altair". Science. 317 (5836): 342–345. arXiv:0706.0867. Bibcode:2007Sci...317..342M. doi:10.1126/science.1143205. PMID 17540860. S2CID 4615273. See second column of Table 1 for stellar parameters.
^ HR 7557, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line November 25, 2008.
^ ^a ^b ^c Entry 19508+0852, The Washington Double Star Catalog Archived 2009-01-31 at the Wayback Machine, United States Naval Observatory. Accessed online November 25, 2008.
^ David Darling. "Altair". The Internet Encyclopedia of Science. Retrieved 2022-08-03.
^ Darling, David. "Summer Triangle". www.daviddarling.info. Retrieved 2008-11-26.
^ ^a ^b Hoboken, Fred Schaaf (2008). The brightest stars : discovering the universe through the sky's most brilliant stars. New Jersey: John Wiley & Sons, Inc. ISBN 978-0-471-70410-2. OCLC 440257051.
^ "Our Local Galactic Neighborhood". NASA. Archived from the original on 2013-11-21.
^ Gilster, Paul (2010-09-01). "Into the Interstellar Void". Centauri Dreams. Retrieved 2017-03-26.
^ ^a ^b ^c Robrade, J.; Schmitt, J. H. M. M. (April 2009), "Altair - the "hottest" magnetically active star in X-rays", Astronomy and Astrophysics, 497 (2): 511–520, arXiv:0903.0966, Bibcode:2009A&A...497..511R, doi:10.1051/0004-6361/200811348, S2CID 14320453.
^ ^a ^b Belle, Gerard T. van; Ciardi, David R.; Thompson, Robert R.; Akeson, Rachel L.; Lada, Elizabeth A. (2001). "Altair's Oblateness and Rotation Velocity from Long-Baseline Interferometry". The Astrophysical Journal. 559 (2): 1155–1164. Bibcode:2001ApJ...559.1155V. doi:10.1086/322340. ISSN 0004-637X. S2CID 13969695.
^ "the definition of altair". www.dictionary.com. Retrieved 2018-09-30.
^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Archived (PDF) from the original on 2022-10-09. Retrieved 28 July 2016.
^ "IAU Catalog of Star Names". Retrieved 28 July 2016.
^ Hanbury Brown, R.; Davis, J.; Allen, L. R.; Rome, J. M. (1967). "The stellar interferometer at Narrabri Observatory-II. The angular diameters of 15 stars". Monthly Notices of the Royal Astronomical Society. 137 (4): 393. Bibcode:1967MNRAS.137..393H. doi:10.1093/mnras/137.4.393.
^ Ohishi, Naoko; Nordgren, Tyler E.; Hutter, Donald J. (2004). "Asymmetric Surface Brightness Distribution of Altair Observed with the Navy Prototype Optical Interferometer". The Astrophysical Journal. 612 (1): 463–471. arXiv:astro-ph/0405301. Bibcode:2004ApJ...612..463O. doi:10.1086/422422. S2CID 15857535.
^ Domiciano de Souza, A.; Kervella, P.; Jankov, S.; Vakili, F.; Ohishi, N.; Nordgren, T. E.; Abe, L. (2005). "Gravitational-darkening of Altair from interferometry". Astronomy & Astrophysics. 442 (2): 567–578. Bibcode:2005A&A...442..567D. doi:10.1051/0004-6361:20042476.
^ ^a ^b "Gazing up at the Man in the Star?" (Press release). National Science Foundation. May 31, 2007. Retrieved 2022-08-03.
^ Knobel, E. B. (June 1895). "Al Achsasi Al Mouakket, on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket". Monthly Notices of the Royal Astronomical Society. 55 (8): 429–438. Bibcode:1895MNRAS..55..429K. doi:10.1093/mnras/55.8.429.
^ ^a ^b ^c Allen, Richard Hinckley (1899). Star-names and their meanings. unknown library. New York, Leipzig [etc.] G.E. Stechert. pp. 59–60.
^ Gingerich, O. (1987). "Zoomorphic Astrolabes and the Introduction of Arabic Star Names into Europe". Annals of the New York Academy of Sciences. 500 (1): 89–104. Bibcode:1987NYASA.500...89G. doi:10.1111/j.1749-6632.1987.tb37197.x. S2CID 84102853.
^ ^a ^b Aboriginal mythology: an A-Z spanning the history of aboriginal mythology from the earliest legends to the present day, Mudrooroo, London: HarperCollins, 1994, ISBN 1-85538-306-3.
^ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived 2008-10-25 at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 26, 2008.
^ Mayers, William Frederick (1874). The Chinese reader's manual: A handbook of biographical, historical ... Harvard University. American Presbyterian Mission Press. pp. 97–98, 161.
^ ^a ^b p. 72, China, Japan, Korea Culture and Customs: Culture and Customs, Ju Brown and John Brown, 2006, ISBN 978-1-4196-4893-9.
^ pp. 105–107, Magic Lotus Lantern and Other Tales from the Han Chinese, Haiwang Yuan and Michael Ann Williams, Libraries Unlimited, 2006, ISBN 978-1-59158-294-6.
^ Ross, Malcolm; Pawley, Andrew; Osmond, Meredith (2007-03-01). The Lexicon of Proto-Oceanic: The Culture and Environment of Ancestral Oceanic Society. The physical environment. Volume 2. ANU E Press. p. 175. ISBN 978-1-921313-19-6.
^ Kelley, David H.; Milone, Eugene F.; Aveni, A.F. (2011). Exploring Ancient Skies: A Survey of Ancient and Cultural Astronomy. New York, New York: Springer. p. 344. ISBN 978-1-4419-7623-9.
^ "'Anybody there?' Astronomers waiting for a reply from Altair". August 20, 2023. Retrieved 2023-08-25.
^ "NASA names next-gen lunar lander Altair". .collectSPACE. December 13, 2007. Retrieved 2022-08-03.
^ "Results of the competition for the best personal names for the Be-103 and the Be-200 amphibious aircraft" (Press release). Beriev Aircraft Company. February 12, 2003. Archived from the original on 2021-11-05. Retrieved 2022-08-03.
^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051.
^ BD+08 4236B -- Star in double system, database entry, SIMBAD. Accessed online November 25, 2008.
^ BD+08 4238 -- Star in double system, database entry, SIMBAD. Accessed online November 25, 2008.

External links

Star with Midriff Bulge Eyed by Astronomers, JPL press release, July 25, 2001.
Spectrum of Altair
Imaging the Surface of Altair, University of Michigan news release detailing the CHARA array direct imaging of the stellar surface in 2007.
PIA04204: Altair, NASA. Image of Altair from the Palomar Testbed Interferometer.
Altair, SolStation.
Secrets of Sun-like star probed, BBC News, June 1, 2007.
Astronomers Capture First Images of the Surface Features of Altair Archived 2009-06-29 at the Wayback Machine, Astromart.com
Image of Altair from Aladin.

[rot-9] Owing to its rapid rotation, Altair's radius is larger at its equator than at its poles; it is also cooler at the equator than at the poles.

[20] From values of v sin i and i in the second column of Table 1, Monnier et al. 2007.

[1] "Altair: definition of Altair in Oxford dictionary (American English)". Archived from the original on May 12, 2014.

[Kunitzsch-2] Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.

[aaa474_2_653-3] van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600

[ducati-4] 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.

[gray_et_al_2003-5] Gray, R. O.; et al. (2003), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I", The Astronomical Journal, 126 (4): 2048, arXiv:astro-ph/0308182, Bibcode:2003AJ....126.2048G, doi:10.1086/378365, S2CID 119417105.

[Buzasi_et_al_2005-6] Buzasi, D. L.; Bruntt, H.; Bedding, T. R.; Retter, A.; Kjeldsen, H.; Preston, H. L.; Mandeville, W. J.; Suarez, J. C.; Catanzarite, J. (February 2005). "Altair: The Brightest δ Scuti Star". The Astrophysical Journal. 619 (2): 1072–1076. arXiv:astro-ph/0405127. Bibcode:2005ApJ...619.1072B. doi:10.1086/426704. ISSN 0004-637X. S2CID 16524681.

[sb0-7] NAME ALTAIR -- Variable Star of delta Sct type, database entry, SIMBAD. Accessed on line November 25, 2008.

[bouchaud2020-8] ^ ^a ^b ^c ^d ^e ^f ^g Bouchaud, K.; Domiciano De Souza, A.; Rieutord, M.; Reese, D. R.; Kervella, P. (2020). "A realistic two-dimensional model of Altair". Astronomy and Astrophysics. 633: A78. arXiv:1912.03138. Bibcode:2020A&A...633A..78B. doi:10.1051/0004-6361/201936830. S2CID 208857428.

[peterson06-10] Peterson, D. M.; Hummel, C. A.; Pauls, T. A.; et al. (2006). "Resolving the Effects of Rotation in Altair with Long-Baseline Interferometry". The Astrophysical Journal. 636 (2): 1087–1097. arXiv:astro-ph/0509236. Bibcode:2006ApJ...636.1087P. doi:10.1086/497981. S2CID 18683397. See Table 2 for stellar parameters.

[aass85_3_1015-11] Malagnini, M. L.; Morossi, C. (November 1990), "Accurate absolute luminosities, effective temperatures, radii, masses and surface gravities for a selected sample of field stars", Astronomy and Astrophysics Supplement Series, 85 (3): 1015–1019, Bibcode:1990A&AS...85.1015M

[monnier07-12] ^ ^a ^b ^c ^d ^e ^f Monnier, J. D.; Zhao, M; Pedretti, E; Thureau, N; Ireland, M; Muirhead, P; Berger, J. P.; Millan-Gabet, R; Van Belle, G; Ten Brummelaar, T; McAlister, H; Ridgway, S; Turner, N; Sturmann, L; Sturmann, J; Berger, D (2007). "Imaging the surface of Altair". Science. 317 (5836): 342–345. arXiv:0706.0867. Bibcode:2007Sci...317..342M. doi:10.1126/science.1143205. PMID 17540860. S2CID 4615273. See second column of Table 1 for stellar parameters.

[bsc1-13] HR 7557, database entry, The Bright Star Catalogue, 5th Revised Ed. (Preliminary Version), D. Hoffleit and W. H. Warren, Jr., CDS ID V/50. Accessed on line November 25, 2008.

[wds-14] Entry 19508+0852, The Washington Double Star Catalog Archived 2009-01-31 at the Wayback Machine, United States Naval Observatory. Accessed online November 25, 2008.

[darlingaltair-15] David Darling. "Altair". The Internet Encyclopedia of Science. Retrieved 2022-08-03.

[darlingsummer-16] Darling, David. "Summer Triangle". www.daviddarling.info. Retrieved 2008-11-26.

[schaaf2008-17] Hoboken, Fred Schaaf (2008). The brightest stars : discovering the universe through the sky's most brilliant stars. New Jersey: John Wiley & Sons, Inc. ISBN 978-0-471-70410-2. OCLC 440257051.

[18] "Our Local Galactic Neighborhood". NASA. Archived from the original on 2013-11-21.

[19] Gilster, Paul (2010-09-01). "Into the Interstellar Void". Centauri Dreams. Retrieved 2017-03-26.

[robrade2009-21] Robrade, J.; Schmitt, J. H. M. M. (April 2009), "Altair - the "hottest" magnetically active star in X-rays", Astronomy and Astrophysics, 497 (2): 511–520, arXiv:0903.0966, Bibcode:2009A&A...497..511R, doi:10.1051/0004-6361/200811348, S2CID 14320453.

[pti2001-22] Belle, Gerard T. van; Ciardi, David R.; Thompson, Robert R.; Akeson, Rachel L.; Lada, Elizabeth A. (2001). "Altair's Oblateness and Rotation Velocity from Long-Baseline Interferometry". The Astrophysical Journal. 559 (2): 1155–1164. Bibcode:2001ApJ...559.1155V. doi:10.1086/322340. ISSN 0004-637X. S2CID 13969695.

[23] "the definition of altair". www.dictionary.com. Retrieved 2018-09-30.

[WGSN-24] "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.

[WGSN1-25] "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Archived (PDF) from the original on 2022-10-09. Retrieved 28 July 2016.

[IAU-CSN-26] "IAU Catalog of Star Names". Retrieved 28 July 2016.

[27] Hanbury Brown, R.; Davis, J.; Allen, L. R.; Rome, J. M. (1967). "The stellar interferometer at Narrabri Observatory-II. The angular diameters of 15 stars". Monthly Notices of the Royal Astronomical Society. 137 (4): 393. Bibcode:1967MNRAS.137..393H. doi:10.1093/mnras/137.4.393.

[28] Ohishi, Naoko; Nordgren, Tyler E.; Hutter, Donald J. (2004). "Asymmetric Surface Brightness Distribution of Altair Observed with the Navy Prototype Optical Interferometer". The Astrophysical Journal. 612 (1): 463–471. arXiv:astro-ph/0405301. Bibcode:2004ApJ...612..463O. doi:10.1086/422422. S2CID 15857535.

[29] Domiciano de Souza, A.; Kervella, P.; Jankov, S.; Vakili, F.; Ohishi, N.; Nordgren, T. E.; Abe, L. (2005). "Gravitational-darkening of Altair from interferometry". Astronomy & Astrophysics. 442 (2): 567–578. Bibcode:2005A&A...442..567D. doi:10.1051/0004-6361:20042476.

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[26]

[27]

[28]

[29]

[30]

[31]

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@@ Line 1: / Line 1: @@
 {{Short description|Brightest star in the constellation Aquila}}
-{{About|the star}}
+{{About|a star in the constellation Aquila}}
 {{good article}}
 {{Starbox begin}}
 {{Starbox image
@@ Line 26: / Line 25: @@
 {{Starbox character
  | type=[[Main sequence]]
- | class = A7V<ref name=sb0/>
+ | class = A7Vn<ref name=gray_et_al_2003/>
  | u-b = +0.09<ref name=ducati/>
  | b-v = +0.22<ref name=ducati/>
@@ Line 34: / Line 33: @@
 }}
 {{Starbox astrometry
- | radial_v = {{nowrap|−26.1 ± 0.9}}<ref name=sb0/>
+ | radial_v = {{val|−26.1|0.9}}<ref name=sb0/>
  | prop_mo_ra = +536.23<ref name=aaa474_2_653/>
  | prop_mo_dec = +385.29<ref name=aaa474_2_653/>
@@ Line 54: / Line 53: @@
 }}
 {{Starbox catalog
-| names = {{odlist | name=Atair | B=α&nbsp;Aquilae, α&nbsp;Aql, Alpha&nbsp;Aquilae, Alpha&nbsp;Aql | F=53&nbsp;Aquilae, 53&nbsp;Aql | BD=+08°4236 | FK5=745 | GCTP=4665.00 | GJ=768 | HD=187642 | HIP=97649 | HR=7557 | LFT=1499 | LHS=3490 | LTT=15795 | NLTT=48314 | SAO=125122 | WDS=19508+0852A }}<ref name=sb0/><ref name=bsc1/><ref name=wds/>
+| names = {{odlist | name=Atair | B=α&nbsp;Aquilae, α&nbsp;Aql, Alpha&nbsp;Aquilae, Alpha&nbsp;Aql | F=53&nbsp;Aquilae, 53&nbsp;Aql | BD=+08°4236 | FK5=745 | GCTP=4665.00 | GJ=768 | HD=187642 | HIP=97649 | HR=7557 | LFT=1499 | LHS=3490 | LTT=15795 | NLTT=48314 | SAO=125122 | WDS=19508+0852A }}<ref name=sb0/><ref name=bsc1/><ref name=wds/> | LA001
 }}
 {{Starbox reference
@@ Line 62: / Line 61: @@
 }}
-'''Altair''' is the brightest [[star]] in the [[constellation]] of [[Aquila (constellation)|Aquila]] and the [[list of brightest stars|twelfth-brightest star]] in the [[night sky]]. It has the [[Bayer designation]] Alpha&nbsp;Aquilae, which is [[Latinisation of names|Latinised]] from '''α&nbsp;Aquilae''' and abbreviated '''Alpha&nbsp;Aql''' or '''α&nbsp;Aql'''. Altair is an [[A-type star|A-type]] [[main-sequence star]] with an [[apparent visual magnitude]] of 0.77 and is one of the vertices of the [[Summer Triangle]] [[Asterism (astronomy)|asterism]]; the other two vertices are marked by [[Deneb]] and [[Vega]].<ref name=sb0/><ref name=darlingaltair/><ref name="darlingsummer">{{Cite web |last=Darling |first=David |title=Summer Triangle |url=http://www.daviddarling.info/encyclopedia/S/Summer_Triangle.html |access-date=2008-11-26 |website=www.daviddarling.info}}</ref> It is located at a distance of {{convert|16.7|ly|pc|abbr=off|lk=on}} from the [[Sun]].<ref name="schaaf2008">{{Cite book |last=Hoboken |first=Fred Schaaf |title=The brightest stars : discovering the universe through the sky's most brilliant stars |publisher=John Wiley & Sons, Inc. |year=2008 |isbn=978-0-471-70410-2 |location=New Jersey |pages= |oclc=440257051}}</ref>{{Citation page|page=194}} Altair is currently in the [[G-cloud]]—a nearby [[interstellar cloud]], an accumulation of gas and dust.<ref>{{Cite web|url=http://interstellar.jpl.nasa.gov/interstellar/probe/introduction/neighborhood.html|title=Our Local Galactic Neighborhood|publisher=[[NASA]]|archive-url=https://web.archive.org/web/20131121061128/http://interstellar.jpl.nasa.gov/interstellar/probe/introduction/neighborhood.html|archive-date=2013-11-21|url-status=dead}}</ref><ref>{{Cite news|url=http://www.centauri-dreams.org/?p=14203|title=Into the Interstellar Void|last=Gilster|first=Paul|date=2010-09-01|work=Centauri Dreams|access-date=2017-03-26|language=en-US}}</ref>
+'''Altair''' is the brightest [[star]] in the [[constellation]] of [[Aquila (constellation)|Aquila]] and the [[list of brightest stars|twelfth-brightest star]] in the [[night sky]]. It has the [[Bayer designation]] Alpha&nbsp;Aquilae, which is [[Latinisation of names|Latinised]] from '''α&nbsp;Aquilae''' and abbreviated '''Alpha&nbsp;Aql''' or '''α&nbsp;Aql'''. Altair is an [[A-type main-sequence star|A-type]] [[main-sequence star]] with an [[apparent visual magnitude]] of 0.77 and is one of the vertices of the [[Summer Triangle]] [[Asterism (astronomy)|asterism]]; the other two vertices are marked by [[Deneb]] and [[Vega]].<ref name=sb0/><ref name=darlingaltair/><ref name="darlingsummer">{{Cite web |last=Darling |first=David |title=Summer Triangle |url=http://www.daviddarling.info/encyclopedia/S/Summer_Triangle.html |access-date=2008-11-26 |website=www.daviddarling.info}}</ref> It is located at a distance of {{convert|16.7|ly|pc|abbr=off|lk=on}} from the [[Sun]].<ref name="schaaf2008">{{Cite book |last=Hoboken |first=Fred Schaaf |title=The brightest stars : discovering the universe through the sky's most brilliant stars |publisher=John Wiley & Sons, Inc. |year=2008 |isbn=978-0-471-70410-2 |location=New Jersey |pages= |oclc=440257051}}</ref>{{Citation page|page=194}} Altair is currently in the [[G-cloud]]—a nearby [[interstellar cloud]], an accumulation of gas and dust.<ref>{{Cite web|url=http://interstellar.jpl.nasa.gov/interstellar/probe/introduction/neighborhood.html|title=Our Local Galactic Neighborhood|publisher=[[NASA]]|archive-url=https://web.archive.org/web/20131121061128/http://interstellar.jpl.nasa.gov/interstellar/probe/introduction/neighborhood.html|archive-date=2013-11-21|url-status=dead}}</ref><ref>{{Cite news|url=http://www.centauri-dreams.org/?p=14203|title=Into the Interstellar Void|last=Gilster|first=Paul|date=2010-09-01|work=Centauri Dreams|access-date=2017-03-26|language=en-US}}</ref>
-Altair rotates rapidly, with a velocity at the [[equator]] of approximately 286&nbsp;km/s.<ref group=nb>From values of ''v'' sin ''i'' and ''i'' in the second column of Table 1, Monnier et al. 2007.</ref><ref name=monnier07/> This is a significant fraction of the star's estimated breakup speed of 400&nbsp;km/s.<ref name=robrade2009/> A study with the [[Palomar Testbed Interferometer]] revealed that Altair is not spherical, but is flattened at the poles due to its high rate of rotation.<ref name="pti2001">{{Cite journal|last1=Belle|first1=Gerard T. van|last2=Ciardi|first2=David R.|last3=Thompson|first3=Robert R.|last4=Akeson|first4=Rachel L.|last5=Lada|first5=Elizabeth A.|year=2001|title=Altair's Oblateness and Rotation Velocity from Long-Baseline Interferometry|url=http://stacks.iop.org/0004-637X/559/i=2/a=1155|journal=The Astrophysical Journal|language=en|volume=559|issue=2|pages=1155–1164|bibcode=2001ApJ...559.1155V|doi=10.1086/322340|issn=0004-637X}}</ref> Other [[interferometric]] studies with multiple telescopes, operating in the [[infrared]], have imaged and confirmed this phenomenon.<ref name="monnier07">{{Cite journal|last2=Zhao|first2=M|last3=Pedretti|first3=E|last4=Thureau|first4=N|last5=Ireland|first5=M|last6=Muirhead|first6=P|last7=Berger|first7=J. P.|last8=Millan-Gabet|first8=R|last9=Van Belle|first9=G|year=2007|title=Imaging the surface of Altair|journal=Science|volume=317|issue=5836|pages=342–345|bibcode=2007Sci...317..342M|doi=10.1126/science.1143205|pmid=17540860|last1=Monnier|first1=J. D.|last10=Ten Brummelaar|first10=T|last11=McAlister|first11=H|last12=Ridgway|first12=S|last13=Turner|first13=N|last14=Sturmann|first14=L|last15=Sturmann|first15=J|last16=Berger|first16=D|arxiv = 0706.0867 |s2cid=4615273}}  See second column of Table 1 for stellar parameters.</ref>
+Altair rotates rapidly, with a velocity at the [[equator]] of approximately 286&nbsp;km/s.<ref group=nb>From values of ''v'' sin ''i'' and ''i'' in the second column of Table 1, Monnier et al. 2007.</ref><ref name=monnier07/> This is a significant fraction of the star's estimated breakup speed of 400&nbsp;km/s.<ref name=robrade2009/> A study with the [[Palomar Testbed Interferometer]] revealed that Altair is not spherical, but is flattened at the poles due to its high rate of rotation.<ref name="pti2001">{{Cite journal|last1=Belle|first1=Gerard T. van|last2=Ciardi|first2=David R.|last3=Thompson|first3=Robert R.|last4=Akeson|first4=Rachel L.|last5=Lada|first5=Elizabeth A.|year=2001|title=Altair's Oblateness and Rotation Velocity from Long-Baseline Interferometry|url=http://stacks.iop.org/0004-637X/559/i=2/a=1155|journal=The Astrophysical Journal|language=en|volume=559|issue=2|pages=1155–1164|bibcode=2001ApJ...559.1155V|doi=10.1086/322340|s2cid=13969695 |issn=0004-637X}}</ref> Other [[interferometric]] studies with multiple telescopes, operating in the [[infrared]], have imaged and confirmed this phenomenon.<ref name="monnier07">{{Cite journal|last2=Zhao|first2=M|last3=Pedretti|first3=E|last4=Thureau|first4=N|last5=Ireland|first5=M|last6=Muirhead|first6=P|last7=Berger|first7=J. P.|last8=Millan-Gabet|first8=R|last9=Van Belle|first9=G|year=2007|title=Imaging the surface of Altair|journal=Science|volume=317|issue=5836|pages=342–345|bibcode=2007Sci...317..342M|doi=10.1126/science.1143205|pmid=17540860|last1=Monnier|first1=J. D.|last10=Ten Brummelaar|first10=T|last11=McAlister|first11=H|last12=Ridgway|first12=S|last13=Turner|first13=N|last14=Sturmann|first14=L|last15=Sturmann|first15=J|last16=Berger|first16=D|arxiv = 0706.0867 |s2cid=4615273}}  See second column of Table 1 for stellar parameters.</ref>
 ==Nomenclature==
-[[File:AquilaCC.jpg|thumb|left|Altair is the brightest star in the constellation Aquila]]
+[[File:AquilaCC.jpg|thumb|left|Altair is the brightest star in the constellation Aquila.]]
-''α Aquilae'' ([[Latinisation of names|Latinised]] to ''Alpha Aquilae'') is the star's [[Bayer designation]]. The traditional name ''Altair'' has been used since medieval times. It is an abbreviation of the [[Arabic]] phrase {{lang|ar|النسر الطائر}} ''Al-Nisr Al-Ta'ir'', "{{lang|en|the flying eagle}}".<ref>{{Cite web|url=https://www.dictionary.com/browse/altair|title=the definition of altair|website=www.dictionary.com|language=en|access-date=2018-09-30}}</ref>
+''α Aquilae'' ([[Latinisation of names|Latinised]] to ''Alpha Aquilae'') is the star's [[Bayer designation]]. The traditional name ''Altair'' has been used since medieval times. It is an abbreviation of the [[Arabic]] phrase {{lang|ar|النسر الطائر}} ''Al-Nisr Al-Ṭa'ir'', "{{lang|en|the flying eagle}}".<ref>{{Cite web|url=https://www.dictionary.com/browse/altair|title=the definition of altair|website=www.dictionary.com|language=en|access-date=2018-09-30}}</ref>
-In 2016, the [[International Astronomical Union]] organized a [[Working Group on Star Names]] (WGSN)<ref name="WGSN">{{cite web | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN)|access-date=22 May 2016}}</ref> to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016<ref name="WGSN1">{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf | title=Bulletin of the IAU Working Group on Star Names, No. 1 |access-date=28 July 2016}}</ref> included a table of the first two batches of names approved by the WGSN, which included ''Altair'' for this star. It is now so entered in the IAU Catalog of Star Names.<ref name="IAU-CSN">{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |access-date=28 July 2016}}</ref>
+In 2016, the [[International Astronomical Union]] organized a [[Working Group on Star Names]] (WGSN)<ref name="WGSN">{{cite web | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN)|access-date=22 May 2016}}</ref> to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016<ref name="WGSN1">{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf |archive-date=2022-10-09 |url-status=live | title=Bulletin of the IAU Working Group on Star Names, No. 1 |access-date=28 July 2016}}</ref> included a table of the first two batches of names approved by the WGSN, which included ''Altair'' for this star. It is now so entered in the IAU Catalog of Star Names.<ref name="IAU-CSN">{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |access-date=28 July 2016}}</ref>
 {{clear left}}
 ==Physical characteristics==
 [[File:Altair-Sun comparison.png|thumb|left|Altair in comparison with the Sun]]
@@ Line 77: / Line 77: @@
 Along with [[β Aquilae]] and [[γ Aquilae]], Altair forms the well-known line of stars sometimes referred to as the ''Family of Aquila'' or ''Shaft of Aquila''.<ref name="schaaf2008" />{{Citation page|page=190}}
-Altair is a [[Type-A star|type-A]] [[main-sequence star]] with about 1.8 times the [[mass of the Sun]] and 11 times [[Solar luminosity|its luminosity]].<ref name=monnier07/><ref name=peterson06/> It is thought to be a young star close to the [[zero age main sequence]] at about 100 million years old, although previous estimates gave an age closer to one billion years old.<ref name=bouchaud2020/>  Altair rotates rapidly, with a rotational period of under eight hours;<ref name=bouchaud2020/> for comparison, the equator of the [[Sun]] makes a complete rotation in a little more than 25 days, but Altair's rotation is similar to, and slightly faster than, those of [[Jupiter]] and [[Saturn]]. Like those two planets, its rapid rotation forces the star to be [[oblate spheroid|oblate]]; its equatorial diameter is over 20 percent greater than its polar diameter.<ref name=monnier07/>
+Altair is a [[Type-A star|type-A]] [[main-sequence star]] with about 1.8 times the [[mass of the Sun]] and 11 times [[Solar luminosity|its luminosity]].<ref name=monnier07/><ref name=peterson06/> It is thought to be a young star close to the [[zero age main sequence]] at about 100 million years old, although previous estimates gave an age closer to one billion years old.<ref name=bouchaud2020/>  Altair rotates rapidly, with a rotational period of under eight hours;<ref name=bouchaud2020/> for comparison, the equator of the [[Sun]] makes a complete rotation in a little more than 25 days, but Altair's rotation is similar to, and slightly faster than, those of [[Jupiter]] and [[Saturn]]. Like those two planets, its rapid rotation causes the star to be [[oblate spheroid|oblate]]; its equatorial diameter is over 20 percent greater than its polar diameter.<ref name=monnier07/>
 [[File:AlphaAqlLightCurve.png|thumb|left|A [[light curve]] for Altair, adapted from Buzasi ''et al.'' (2005)<ref name="Buzasi et al 2005"/>]]
@@ Line 84: / Line 84: @@
 ===Rotational effects===
 [[Image:Altair_PR_image6_(white).jpg|thumb|left|Direct image of Altair, taken with the [[CHARA array]]]]
-The angular diameter of Altair was measured [[interferometrically]] by [[R. Hanbury Brown]] and his co-workers at [[Narrabri Stellar Intensity Interferometer|Narrabri Observatory]] in the 1960s. They found a diameter of 3{{nbsp}}[[milliarcseconds]].<ref>{{cite journal |bibcode=1967MNRAS.137..393H |title=The stellar interferometer at Narrabri Observatory-II. The angular diameters of 15 stars |last1=Hanbury Brown |first1=R. |last2=Davis |first2=J. |last3=Allen |first3=L. R. |last4=Rome |first4=J. M. |journal=Monthly Notices of the Royal Astronomical Society |year=1967 |volume=137 |issue=4 |page=393 |doi=10.1093/mnras/137.4.393 }}</ref> Although Hanbury Brown et al. realized that Altair would be rotationally flattened, they had insufficient data to experimentally observe its oblateness. Later, using [[infrared]] interferometric measurements made by the [[Palomar Testbed Interferometer]] in 1999 and 2000, Altair was found to be flattened. This work was published by [[Gerard van Belle|G. T. van Belle]], [[David Ciardi|David R. Ciardi]] and their co-authors in 2001.<ref name=pti2001/>
+The angular diameter of Altair was measured [[interferometrically]] by [[R. Hanbury Brown]] and his co-workers at [[Narrabri Stellar Intensity Interferometer|Narrabri Observatory]] in the 1960s. They found a diameter of 3{{nbsp}}[[milliarcseconds]].<ref>{{cite journal |bibcode=1967MNRAS.137..393H |title=The stellar interferometer at Narrabri Observatory-II. The angular diameters of 15 stars |last1=Hanbury Brown |first1=R. |last2=Davis |first2=J. |last3=Allen |first3=L. R. |last4=Rome |first4=J. M. |journal=Monthly Notices of the Royal Astronomical Society |year=1967 |volume=137 |issue=4 |page=393 |doi=10.1093/mnras/137.4.393 |doi-access=free }}</ref> Although Hanbury Brown et al. realized that Altair would be rotationally flattened, they had insufficient data to experimentally observe its oblateness. Later, using [[infrared]] interferometric measurements made by the [[Palomar Testbed Interferometer]] in 1999 and 2000, Altair was found to be flattened. This work was published by [[Gerard van Belle|G. T. van Belle]], [[David Ciardi|David R. Ciardi]] and their co-authors in 2001.<ref name=pti2001/>
 Theory predicts that, owing to Altair's rapid rotation, its [[surface gravity]] and [[effective temperature]] should be lower at the equator, making the equator less luminous than the poles. This phenomenon, known as [[gravity darkening]] or the [[von Zeipel effect]], was confirmed for Altair by measurements made by the [[Navy Precision Optical Interferometer]] in 2001, and analyzed by Ohishi et al. (2004) and Peterson et al. (2006).<ref name=peterson06/><ref>{{cite journal | doi = 10.1086/422422| title = Asymmetric Surface Brightness Distribution of Altair Observed with the Navy Prototype Optical Interferometer| year = 2004| last1 = Ohishi| first1 = Naoko| last2 = Nordgren| first2 = Tyler E.| last3 = Hutter| first3 = Donald J.| journal = The Astrophysical Journal| volume = 612| issue = 1| pages = 463–471| arxiv = astro-ph/0405301| bibcode = 2004ApJ...612..463O| s2cid = 15857535}}</ref> Also, A. Domiciano de Souza et al. (2005) verified gravity darkening using the measurements made by the Palomar and Navy interferometers, together with new measurements made by the VINCI instrument at the [[VLTI]].<ref>{{cite journal | doi = 10.1051/0004-6361:20042476| title = Gravitational-darkening of Altair from interferometry| year = 2005| last1 = Domiciano de Souza| first1 = A. | last2 = Kervella| first2 = P.| last3 = Jankov| first3 = S.| last4 = Vakili| first4 = F.| last5 = Ohishi| first5 = N.| last6 = Nordgren| first6 = T. E.| last7 = Abe| first7 = L.| journal = Astronomy & Astrophysics| volume = 442| issue = 2| pages = 567–578| bibcode = 2005A&A...442..567D| doi-access = free}}</ref>
@@ Line 93: / Line 93: @@
 ==Etymology, mythology and culture==
 [[Image:Altair.jpg|Altair|thumb|left]]
-The term ''Al Nesr Al Tair'' appeared in [[Al Achsasi al Mouakket]]'s catalogue, which was translated into [[Latin]] as ''Vultur Volans''.<ref>{{cite journal|last=Knobel|first= E. B.|title=Al Achsasi Al Mouakket, on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket|journal=Monthly Notices of the Royal Astronomical Society|volume=55|issue= 8|pages=429–438|date=June 1895|bibcode=1895MNRAS..55..429K|doi=10.1093/mnras/55.8.429|doi-access=free}}</ref> This name was applied by the Arabs to the [[asterism (astronomy)|asterism]] of Altair, [[β Aquilae]] and [[γ Aquilae]] and probably goes back to the ancient Babylonians and Sumerians, who called Altair "the eagle star".<ref name="Kunitzsch" />{{Citation page|pages=17-18}} The spelling ''Atair'' has also been used.<ref name="allen">{{Cite book |last=Allen |first=Richard Hinckley |url=http://archive.org/details/bub_gb_5xQuAAAAIAAJ |title=Star-names and their meanings |date= |publisher=New York, Leipzig [etc.] G.E. Stechert |others=unknown library |year=1899 |pages=59-60}}</ref> Medieval [[astrolabe]]s of England and Western Europe depicted Altair and Vega as birds.<ref>{{Cite journal | last1 = Gingerich | first1 = O.| doi = 10.1111/j.1749-6632.1987.tb37197.x | title = Zoomorphic Astrolabes and the Introduction of Arabic Star Names into Europe | journal = Annals of the New York Academy of Sciences | volume = 500 | pages = 89–104 | year = 1987 | issue = 1|bibcode = 1987NYASA.500...89G | s2cid = 84102853}}</ref>
+The term ''Al Nesr Al Tair'' appeared in [[Al Achsasi al Mouakket]]'s catalogue, which was translated into [[Latin]] as ''Vultur Volans''.<ref>{{cite journal|last=Knobel|first= E. B.|title=Al Achsasi Al Mouakket, on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket|journal=Monthly Notices of the Royal Astronomical Society|volume=55|issue= 8|pages=429–438|date=June 1895|bibcode=1895MNRAS..55..429K|doi=10.1093/mnras/55.8.429|doi-access=free}}</ref> This name was applied by the Arabs to the [[asterism (astronomy)|asterism]] of Altair, [[β Aquilae]] and [[γ Aquilae]] and probably goes back to the ancient Babylonians and Sumerians, who called Altair "the eagle star".<ref name="Kunitzsch" />{{Citation page|pages=17-18}} The spelling ''Atair'' has also been used.<ref name="allen">{{Cite book |last=Allen |first=Richard Hinckley |url=http://archive.org/details/bub_gb_5xQuAAAAIAAJ |title=Star-names and their meanings |publisher=New York, Leipzig [etc.] G.E. Stechert |others=unknown library |year=1899 |pages=59–60}}</ref> Medieval [[astrolabe]]s of England and Western Europe depicted Altair and Vega as birds.<ref>{{Cite journal | last1 = Gingerich | first1 = O.| doi = 10.1111/j.1749-6632.1987.tb37197.x | title = Zoomorphic Astrolabes and the Introduction of Arabic Star Names into Europe | journal = Annals of the New York Academy of Sciences | volume = 500 | pages = 89–104 | year = 1987 | issue = 1|bibcode = 1987NYASA.500...89G | s2cid = 84102853}}</ref>
 The [[Koori]] people of [[Victoria (Australia)|Victoria]] also knew Altair as ''Bunjil'', the [[wedge-tailed eagle]], and β and γ Aquilae are his two wives the [[black swan]]s. The people of the [[Murray River]] knew the star as ''Totyerguil''.<ref name="mudrooroo1994">''Aboriginal mythology: an A-Z spanning the history of aboriginal mythology from the earliest legends to the present day'', Mudrooroo, London: HarperCollins, 1994, {{ISBN|1-85538-306-3}}.</ref>{{Citation page|page=4}} The Murray River was formed when ''Totyerguil'' the hunter speared ''Otjout'', a giant [[Murray cod]], who, when wounded, churned a channel across southern Australia before entering the sky as the constellation [[Delphinus]].<ref name="mudrooroo1994" />{{Citation page|page=115}}
-In Chinese belief, the asterism consisting of Altair, β Aquilae and γ Aquilae is known as ''Hé Gǔ'' ({{lang|zh|河鼓}}; lit. "river drum").<ref name=allen/> The [[Chinese star names|Chinese name]] for Altair is thus ''Hé Gǔ èr'' ({{lang|zh|河鼓二}}; lit. "river drum two", meaning the "second star of the drum at the river").<ref>{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm 香港太空館 - 研究資源 - 亮星中英對照表] {{webarchive|url=https://web.archive.org/web/20081025110153/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm |date=2008-10-25 }}, Hong Kong Space Museum. Accessed on line November 26, 2008.</ref> However, Altair is better known by its other names: ''Qiān Niú Xīng'' ({{lang|zh-hans|牵牛星}} / {{lang|zh-hant|牽牛星}}) or ''Niú Láng Xīng'' ({{lang|zh|牛郎星}}), translated as the ''cowherd star''.<ref>{{Cite book |last=Mayers |first=William Frederick |url=http://archive.org/details/chinesereadersm01mayegoog |title=The Chinese reader's manual: A handbook of biographical, historical ... |date= |publisher=American Presbyterian Mission Press |others=Harvard University |year=1874 |pages=97-98, 161 |author-link=William Frederick Mayers}}</ref><ref name=brown>p. 72, ''China, Japan, Korea Culture and Customs: Culture and Customs'', Ju Brown and John Brown, 2006, {{ISBN|978-1-4196-4893-9}}.</ref> These names are an allusion to a love story, ''[[The Cowherd and the Weaver Girl]]'', in which Niulang (represented by Altair) and his two children (represented by [[β Aquilae]] and [[γ Aquilae]]) are separated from respectively their wife and mother Zhinu (represented by Vega) by the [[Milky Way]]. They are only permitted to meet once a year, when magpies form a bridge to allow them to cross the Milky Way.<ref name=brown/><ref>pp. 105–107, ''Magic Lotus Lantern and Other Tales from the Han Chinese'', Haiwang Yuan and Michael Ann Williams, Libraries Unlimited, 2006, {{ISBN|978-1-59158-294-6}}.</ref>
+In Chinese belief, the asterism consisting of Altair, β Aquilae and γ Aquilae is known as ''Hé Gǔ'' ({{lang|zh|河鼓}}; lit. "river drum").<ref name=allen/> The [[Chinese star names|Chinese name]] for Altair is thus ''Hé Gǔ èr'' ({{lang|zh|河鼓二}}; lit. "river drum two", meaning the "second star of the drum at the river").<ref>{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm 香港太空館 - 研究資源 - 亮星中英對照表] {{webarchive|url=https://web.archive.org/web/20081025110153/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm |date=2008-10-25 }}, Hong Kong Space Museum. Accessed on line November 26, 2008.</ref> However, Altair is better known by its other names: ''Qiān Niú Xīng'' ({{lang|zh-hans|牵牛星}} / {{lang|zh-hant|牽牛星}}) or ''Niú Láng Xīng'' ({{lang|zh|牛郎星}}), translated as the ''cowherd star''.<ref>{{Cite book |last=Mayers |first=William Frederick |url=http://archive.org/details/chinesereadersm01mayegoog |title=The Chinese reader's manual: A handbook of biographical, historical ... |publisher=American Presbyterian Mission Press |others=Harvard University |year=1874 |pages=97–98, 161 |author-link=William Frederick Mayers}}</ref><ref name=brown>p. 72, ''China, Japan, Korea Culture and Customs: Culture and Customs'', Ju Brown and John Brown, 2006, {{ISBN|978-1-4196-4893-9}}.</ref> These names are an allusion to a love story, ''[[The Cowherd and the Weaver Girl]]'', in which Niulang (represented by Altair) and his two children (represented by [[β Aquilae]] and [[γ Aquilae]]) are separated from respectively their wife and mother Zhinu (represented by Vega) by the [[Milky Way]]. They are only permitted to meet once a year, when magpies form a bridge to allow them to cross the Milky Way.<ref name=brown/><ref>pp. 105–107, ''Magic Lotus Lantern and Other Tales from the Han Chinese'', Haiwang Yuan and Michael Ann Williams, Libraries Unlimited, 2006, {{ISBN|978-1-59158-294-6}}.</ref>
-The people of [[Micronesia]] called Altair ''Mai-lapa'', meaning "big/old breadfruit", while the [[Māori people]] called this star ''Poutu-te-rangi'', meaning "pillar of heaven".<ref>{{Cite book |last=Ross |first=Malcolm |url=https://books.google.com/books?id=bJFfm59fVr4C |title=The Lexicon of Proto-Oceanic: The Culture and Environment of Ancestral Oceanic Society. The physical environment. Volume 2 |last2=Pawley |first2=Andrew |last3=Osmond |first3=Meredith |date=2007-03-01 |publisher=ANU E Press |isbn=978-1-921313-19-6 |page=175 |language=en}}</ref>
+The people of [[Micronesia]] called Altair ''Mai-lapa'', meaning "big/old breadfruit", while the [[Māori people]] called this star ''Poutu-te-rangi'', meaning "pillar of heaven".<ref>{{Cite book |last1=Ross |first1=Malcolm |url=https://books.google.com/books?id=bJFfm59fVr4C |title=The Lexicon of Proto-Oceanic: The Culture and Environment of Ancestral Oceanic Society. The physical environment. Volume 2 |last2=Pawley |first2=Andrew |last3=Osmond |first3=Meredith |date=2007-03-01 |publisher=ANU E Press |isbn=978-1-921313-19-6 |page=175 |language=en}}</ref>
 In Western [[astrology]], the star was ill-omened, portending danger from [[reptile]]s.<ref name=allen/>
@@ Line 105: / Line 105: @@
 This star is one of the asterisms used by [[Bugis]] sailors for navigation, called ''bintoéng timoro'', meaning "eastern star".<ref name="kelley11">{{cite book|author1=Kelley, David H. |author2=Milone, Eugene F. |author3=Aveni, A.F. |title=Exploring Ancient Skies: A Survey of Ancient and Cultural Astronomy|publisher=Springer|location=New York, New York|year=2011|page=344|isbn=978-1-4419-7623-9|url=https://books.google.com/books?id=ILBuYcGASxcC&pg=PA307}}</ref>
+A group of [[Japan]]ese scientists sent a radio signal to Altair in 1983 with the hopes of contacting extraterrestrial life.<ref>{{cite news |url=https://www.asahi.com/ajw/articles/14985246 |title='Anybody there?' Astronomers waiting for a reply from Altair |date=August 20, 2023 |website= |access-date=2023-08-25 }}</ref>
-NASA announced ''Altair'' as the name of the [[Lunar Surface Access Module]] (LSAM) on December 13, 2007.<ref>{{cite news |url=http://www.collectspace.com/news/news-121307a.html |title=NASA names next-gen lunar lander Altair |date=December 13, 2007 |website=.collectSPACE |access-date=2022-08-03 }}</ref> The Russian-made [[Beriev Be-200]] Altair seaplane is also named after the star.<ref>{{cite press release |url=http://www.beriev.com/eng/Pr_rel_e/pr_58e.html |title=Results of the competition for the best personal names for the Be-103 and the Be-200 amphibious aircraft |publisher=[[Beriev Aircraft Company]] |date=February 12, 2003 |access-date=2022-08-03 }}</ref>
+NASA announced ''Altair'' as the name of the [[Lunar Surface Access Module]] (LSAM) on December 13, 2007.<ref>{{cite news |url=http://www.collectspace.com/news/news-121307a.html |title=NASA names next-gen lunar lander Altair |date=December 13, 2007 |website=.collectSPACE |access-date=2022-08-03 }}</ref> The Russian-made [[Beriev Be-200]] Altair seaplane is also named after the star.<ref>{{cite press release |url=http://www.beriev.com/eng/Pr_rel_e/pr_58e.html |title=Results of the competition for the best personal names for the Be-103 and the Be-200 amphibious aircraft |publisher=[[Beriev Aircraft Company]] |date=February 12, 2003 |access-date=2022-08-03 |archive-date=2021-11-05 |archive-url=https://web.archive.org/web/20211105063444/http://www.beriev.com/eng/Pr_rel_e/pr_58e.html |url-status=dead }}</ref>
 {{clear left}}
 ==Visual companions==
-The bright primary [[star]] has the [[multiple star]] designation [[Washington Double Star Catalog|WDS]]&nbsp;19508+0852A and has several faint visual companion stars, WDS&nbsp;19508+0852B, C, D, E, F and G.<ref name=wds/> All are much more distant than Altair and not physically associated.<ref>{{cite DR2}}</ref>
+The bright primary [[star]] has the [[multiple star]] designation [[Washington Double Star Catalog|WDS]]&nbsp;19508+0852A and has several faint visual companion stars, WDS&nbsp;19508+0852B, C, D, E, F and G.<ref name="wds" /> All are much more distant than Altair and not physically associated.<ref>{{cite DR2}}</ref>
 {{Componentbox begin
 |designation=[[Washington Double Star Catalog|WDS]] 19508+0852
-|footnote=<ref name=wds>Entry 19508+0852,
+|footnote=<ref name="wds">Entry 19508+0852,
 [http://ad.usno.navy.mil/wds/Webtextfiles/wdsnewframe4.html The Washington Double Star Catalog] {{Webarchive|url=https://web.archive.org/web/20090131051103/http://ad.usno.navy.mil/wds/Webtextfiles/wdsnewframe4.html |date=2009-01-31 }},
-[[United States Naval Observatory]]. Accessed on line November 25, 2008.</ref>
+[[United States Naval Observatory]]. Accessed online November 25, 2008.</ref>
 |expanded = yes
 |centered = yes
@@ Line 127: / Line 129: @@
 |ra = {{RA|19|50|40.5}}
 |dec = {{DEC|+08|52|13}}
-|radec_footnote = <ref name=sb1>{{SIMBAD link|CCDM+19508%2B0852B|BD+08 4236B -- Star in double system}}, database entry, [[SIMBAD]]. Accessed on line November 25, 2008.</ref>
+|radec_footnote = <ref name="sb1">{{SIMBAD link|CCDM+19508%2B0852B|BD+08 4236B -- Star in double system}}, database entry, [[SIMBAD]]. Accessed online November 25, 2008.</ref>
 |simbad = CCDM+19508%2B0852B
 |expanded = yes
@@ Line 140: / Line 142: @@
 |ra = {{RA|19|51|00.8}}
 |dec = {{DEC|+08|50|58}}
-|radec_footnote = <ref name=sb2>{{SIMBAD link|CCDM+19508%2B0852C|BD+08 4238 -- Star in double system}}, database entry, [[SIMBAD]]. Accessed on line November 25, 2008.</ref>
+|radec_footnote = <ref name="sb2">{{SIMBAD link|CCDM+19508%2B0852C|BD+08 4238 -- Star in double system}}, database entry, [[SIMBAD]]. Accessed online November 25, 2008.</ref>
 |simbad = CCDM+19508%2B0852C
 |expanded = yes
@@ Line 226: / Line 228: @@
 <ref name=darlingaltair>{{cite web |url=http://www.daviddarling.info/encyclopedia/A/Altair.html |title=Altair |website=The Internet Encyclopedia of Science |author=David Darling |access-date=2022-08-03 }}</ref>
-<ref name=peterson06>{{cite journal | doi = 10.1086/497981| title = Resolving the Effects of Rotation in Altair with Long‐Baseline Interferometry| year = 2006| last1 = Peterson| first1 = D. M.| last2 = Hummel| first2 = C. A.| last3 = Pauls| first3 = T. A.| last4 = Armstrong| first4 = J. T.| last5 = Benson| first5 = J. A.| last6 = Gilbreath| first6 = G. C.| last7 = Hindsley| first7 = R. B.| last8 = Hutter| first8 = D. J.| last9 = Johnston| first9 = K. J.| last10 = Mozurkewich| first10 = D.| last11 = Schmitt| first11 = H.| display-authors=3 | journal = The Astrophysical Journal| volume = 636| issue = 2| pages = 1087–1097| arxiv = astro-ph/0509236| bibcode = 2006ApJ...636.1087P| s2cid = 18683397}} See Table 2 for stellar parameters.</ref>
+<ref name=peterson06>{{cite journal | doi = 10.1086/497981| title = Resolving the Effects of Rotation in Altair with Long-Baseline Interferometry| year = 2006| last1 = Peterson| first1 = D. M.| last2 = Hummel| first2 = C. A.| last3 = Pauls| first3 = T. A.| last4 = Armstrong| first4 = J. T.| last5 = Benson| first5 = J. A.| last6 = Gilbreath| first6 = G. C.| last7 = Hindsley| first7 = R. B.| last8 = Hutter| first8 = D. J.| last9 = Johnston| first9 = K. J.| last10 = Mozurkewich| first10 = D.| last11 = Schmitt| first11 = H.| display-authors=3 | journal = The Astrophysical Journal| volume = 636| issue = 2| pages = 1087–1097| arxiv = astro-ph/0509236| bibcode = 2006ApJ...636.1087P| s2cid = 18683397}} See Table 2 for stellar parameters.</ref>
 <ref name=robrade2009>{{citation | title=Altair - the "hottest" magnetically active star in X-rays | last1=Robrade | first1=J. | last2=Schmitt | first2=J. H. M. M. | journal=Astronomy and Astrophysics | volume=497 | issue=2 | pages=511–520 | date=April 2009 | doi=10.1051/0004-6361/200811348 | bibcode=2009A&A...497..511R | arxiv=0903.0966 | s2cid=14320453 | postscript=. }}</ref>
+<ref name=gray_et_al_2003>{{citation | postscript=.
+ | title=Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I
+ | last1=Gray | first1=R. O. | last2=Corbally | first2=C. J.
+ | last3=Garrison | first3=R. F. | last4=McFadden | first4=M. T.
+ | last5=Robinson | first5=P. E. | display-authors=1
+ | journal=The Astronomical Journal
+ | volume=126 | issue=4 | pages=2048 | year=2003
+ | bibcode=2003AJ....126.2048G | doi=10.1086/378365
+ | arxiv=astro-ph/0308182 | s2cid=119417105 }}</ref>
 }}
@@ Line 235: / Line 247: @@
 {{Commons category|Altair}}
 * [https://web.archive.org/web/20090414054427/http://origins.jpl.nasa.gov/library/story/072501-a.html Star with Midriff Bulge Eyed by Astronomers], JPL press release, July 25, 2001.
+* [https://sl.voxastro.org/library/UVES-POP/details/?star=Altair Spectrum of Altair]
 * [http://www.astro.lsa.umich.edu/~monnier/Altair2007/altair2007.html Imaging the Surface of Altair], University of Michigan news release detailing the CHARA array direct imaging of the stellar surface in 2007.
 * [http://photojournal.jpl.nasa.gov/catalog/PIA04204 PIA04204: Altair], NASA. Image of Altair from the [[Palomar Testbed Interferometer]].
 * [http://www.solstation.com/stars/altair.htm Altair], ''SolStation''.
 * [http://news.bbc.co.uk/2/hi/science/nature/6709345.stm Secrets of Sun-like star probed], ''BBC News'', June 1, 2007.
-* [http://www.astromart.com/news/news.asp?news_id=697 Astronomers Capture First Images of the Surface Features of Altair], ''Astromart.com''
+* [http://www.astromart.com/news/news.asp?news_id=697 Astronomers Capture First Images of the Surface Features of Altair] {{Webarchive|url=https://web.archive.org/web/20090629063240/http://www.astromart.com/news/news.asp?news_id=697 |date=2009-06-29 }}, ''Astromart.com''
 * [http://aladin.u-strasbg.fr/AladinPreview?-c=NAME+ALTAIR&ident=NAME+ALTAIR&submit=Aladin+previewer Image of Altair] from [[Aladin Sky Atlas|Aladin]].
@@ Line 262: / Line 275: @@
 [[Category:Astronomical objects known since antiquity]]
 [[Category:Gliese and GJ objects|0768]]
+[[Category:TIC objects]]

Observation data Epoch J2000.097 Equinox J2000.0 (ICRS)
Location of Altair (circled)
Constellation	Aquila
Pronunciation	/ˈæltɛər/, /ˈæltaɪər/^[1]^[2]
Right ascension	19^h 50^m 46.99855^s^[3]
Declination	+08° 52′ 05.9563″^[3]
Apparent magnitude (V)	0.76^[4]
Characteristics
Evolutionary stage	Main sequence
Spectral type	A7Vn^[5]
U−B color index	+0.09^[4]
B−V color index	+0.22^[4]
V−R color index	+0.14^[4]
R−I color index	+0.13^[4]
Variable type	Delta Scuti^[6]
Astrometry

Radial velocity (R_v)	−26.1±0.9^[7] km/s
Proper motion (μ)	RA: +536.23^[3] mas/yr Dec.: +385.29^[3] mas/yr
Parallax (π)	194.95 ± 0.57 mas^[3]
Distance	16.73 ± 0.05 ly (5.13 ± 0.01 pc)
Absolute magnitude (M_V)	2.22^[6]

Details

Mass	1.86±0.03^[8] `M`_☉
Radius	1.57 – 2.01^[8]^{[nb 1]} `R`_☉
Luminosity	10.6^[9] `L`_☉
Surface gravity (log g)	4.29^[10] cgs
Temperature	6,860 – 8,621^[8]^{[nb 1]} K
Metallicity [Fe/H]	−0.2^[11] dex
Rotation	7.77 hours^[9]
Rotational velocity (v sin i)	242^[8] km/s
Age	100^[8] Myr

Other designations
Atair, α Aquilae, α Aql, Alpha Aquilae, Alpha Aql, 53 Aquilae, 53 Aql, BD+08°4236, FK5 745, GJ 768, HD 187642, HIP 97649, HR 7557, SAO 125122, WDS 19508+0852A, LFT 1499, LHS 3490, LTT 15795, NLTT 48314^[7]^[12]^[13]
Database references
SIMBAD	data