[{"@context":"http:\/\/schema.org\/","@type":"BlogPosting","@id":"https:\/\/wiki.edu.vn\/en\/wiki24\/alpha-sagittarii-wikipedia\/#BlogPosting","mainEntityOfPage":"https:\/\/wiki.edu.vn\/en\/wiki24\/alpha-sagittarii-wikipedia\/","headline":"Alpha Sagittarii – Wikipedia","name":"Alpha Sagittarii – Wikipedia","description":"From Wikipedia, the free encyclopedia Star in the constellation of Sagittarius Alpha Sagittarii Location of \u03b1 Sagittarii (circled) Observation dataEpoch","datePublished":"2016-09-19","dateModified":"2016-09-19","author":{"@type":"Person","@id":"https:\/\/wiki.edu.vn\/en\/wiki24\/author\/lordneo\/#Person","name":"lordneo","url":"https:\/\/wiki.edu.vn\/en\/wiki24\/author\/lordneo\/","image":{"@type":"ImageObject","@id":"https:\/\/secure.gravatar.com\/avatar\/c9645c498c9701c88b89b8537773dd7c?s=96&d=mm&r=g","url":"https:\/\/secure.gravatar.com\/avatar\/c9645c498c9701c88b89b8537773dd7c?s=96&d=mm&r=g","height":96,"width":96}},"publisher":{"@type":"Organization","name":"Enzyklop\u00e4die","logo":{"@type":"ImageObject","@id":"https:\/\/wiki.edu.vn\/wiki4\/wp-content\/uploads\/2023\/08\/download.jpg","url":"https:\/\/wiki.edu.vn\/wiki4\/wp-content\/uploads\/2023\/08\/download.jpg","width":600,"height":60}},"image":{"@type":"ImageObject","@id":"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/5\/54\/Sagittarius_IAU.svg\/240px-Sagittarius_IAU.svg.png","url":"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/thumb\/5\/54\/Sagittarius_IAU.svg\/240px-Sagittarius_IAU.svg.png","height":"296","width":"240"},"url":"https:\/\/wiki.edu.vn\/en\/wiki24\/alpha-sagittarii-wikipedia\/","about":["Wiki"],"wordCount":4507,"articleBody":"From Wikipedia, the free encyclopediaStar in the constellation of SagittariusAlpha SagittariiLocation of \u03b1 Sagittarii (circled)Observation dataEpoch J2000\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0Equinox J2000ConstellationSagittariusRight ascension19h 23m 53.17483s[1]Declination\u221240\u00b0\u00a036\u2032\u00a057.3705\u2033[1]Apparent\u00a0magnitude\u00a0(V)+3.97[2]CharacteristicsSpectral\u00a0typeB8\u00a0V[3]U\u2212B color index\u22120.33[2]B\u2212V color index\u22120.10[2]AstrometryRadial velocity (Rv)\u22120.7[4]\u00a0km\/sProper motion (\u03bc) RA:\u00a0+30.49[1]\u00a0mas\/yr Dec.:\u00a0\u2212119.21[1]\u00a0mas\/yr Parallax (\u03c0)17.94\u00a0\u00b1\u00a00.22\u00a0mas[1]Distance182 \u00b1 2\u00a0ly (55.7 \u00b1 0.7\u00a0pc)Absolute\u00a0magnitude\u00a0(MV)+0.23[5]DetailsMass2.95[6]\u00a0M\u2609Luminosity117[7]\u00a0L\u2609Surface gravity (log\u00a0g)4.11[6]\u00a0cgsTemperature12,387\u00b1421[6]\u00a0KMetallicity [Fe\/H]\u22120.02[8]\u00a0dexRotational velocity (v\u00a0sin\u00a0i)71[6]\u00a0km\/sAge33[6]\u00a0MyrOther designationsDatabase referencesSIMBADdataAlpha Sagittarii (\u03b1\u00a0Sagittarii, abbreviated Alpha\u00a0Sgr, \u03b1\u00a0Sgr), also named Rukbat ,[9][10] is a star in the constellation of Sagittarius.Table of ContentsProperties[edit]Nomenclature[edit]In popular culture[edit]References[edit]External links[edit]Properties[edit]Alpha Sagittarii is a blue, class B dwarf star. It does not appear particularly bright in the sky to the naked eye, with a visual apparent magnitude of +3.97.The star has an effective temperature about twice that of the Sun and is nearly three times as massive, with a luminosity in visible wavelengths about 117 times that of the Sun. Based on an excess emission of infrared radiation, it may have a debris disk, much like Vega.[8] It is a single-lined spectroscopic binary system. The ROSAT All Sky Survey discovered that Alpha Sagittarii is emitting an excess flux of X-rays, which is not expected to originate from a star of this spectral class. The most likely explanation is that the companion is an active pre-main sequence star or else a star that has just reached the main sequence.[11]Nomenclature[edit]\u03b1 Sagittarii (Latinised to Alpha Sagittarii) is the star’s Bayer designation. It is unclear why Bayer designated this star as the alpha, rather than Epsilon Sagittarii or Sigma Sagittarii. This led some old star charts to occasionally depict Alpha and Beta Sagittarii as much brighter than they are in reality, as they are invisible from northern Europe, being too far south to see there.The star bore the traditional names Rukbat and Alrami, derived from the Arabic rukbat al-r\u0101m\u012b ‘the knee of the archer’. The star Delta Cassiopeiae also bore the traditional names Ruchbah or Rukbat, from the Arabic word \u0631\u0643\u0628\u0629 rukbah meaning “knee”. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[12] to catalog and standardize proper names for stars. The WGSN’s first bulletin of July 2016[13] included a table of the first two batches of names approved by the WGSN; which included Rukbat for this star (Delta Cassiopeiae was later given the name Ruchbah[10]).In Chinese, \u5929\u6df5 (Ti\u0101n Yu\u0101n), meaning Celestial Spring, refers to an asterism consisting of Alpha Sagittarii, Beta\u00b9 Sagittarii and Beta\u00b2 Sagittarii. Consequently, the Chinese name for Alpha Sagittarii itself is \u5929\u6df5\u4e09 (Ti\u0101n Yu\u0101n s\u0101n, English: the Third Star of Celestial Spring.)[14]This star, together with  Beta\u00b9 Sagittarii and Beta\u00b2 Sagittarii, were Al \u1e62uradain (\u0623\u0644\u0633\u0631\u062f\u064a\u0646), the two Surad, desert birds.[15]In popular culture[edit]A fictionalized version of the Rukbat system is the setting for Anne McCaffrey’s Dragonriders of Pern series of novels. In the canon of this series, the system has five planets in standard orbits, two asteroid belts, an Oort cloud, and has also captured a rogue planet into a highly eccentric orbit which passes both through the Oort cloud and through the inner solar system on a 250 year orbit.References[edit]^ a b c d e van Leeuwen, Floor (November 2007), “Validation of the new Hipparcos reduction”, Astronomy and Astrophysics, 474 (2): 653\u2013664, arXiv:0708.1752v1, Bibcode:2007A&A…474..653V, doi:10.1051\/0004-6361:20078357, S2CID\u00a018759600 Note: see VizieR catalogue I\/311.^ a b c Johnson, H. L.;  et\u00a0al. (1966), “UBVRIJKL photometry of the bright stars”, Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL…4…99J^ Buscombe, W. (1962), “Spectral classification of Southern fundamental stars”, Mount Stromlo Observatory Mimeogram, 4: 1, Bibcode:1962MtSOM…4….1B^ Evans, D. S. (June 20\u201324, 1966),  Batten, Alan Henry; Heard, John Frederick (eds.), “The Revision of the General Catalogue of Radial Velocities”, Determination of Radial Velocities and Their Applications, Proceedings from IAU Symposium No. 30, University of Toronto: International Astronomical Union, 30: 57, Bibcode:1967IAUS…30…57E^ Anderson, E.; Francis, Ch. (2012), “XHIP: An extended hipparcos compilation”, Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL…38..331A, doi:10.1134\/S1063773712050015, S2CID\u00a0119257644.^ a b c d e David, Trevor J.; Hillenbrand, Lynne A. (2015), “The Ages of Early-Type Stars: Str\u00f6mgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets”, The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ…804..146D, doi:10.1088\/0004-637X\/804\/2\/146, S2CID\u00a033401607.^ Zorec, J.; Royer, F. (January 2012), “Rotational velocities of A-type stars. IV. Evolution of rotational velocities”, Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A…537A.120Z, doi:10.1051\/0004-6361\/201117691, S2CID\u00a055586789.^ a b Saffe, C.;  et\u00a0al. (October 2008), “Spectroscopic metallicities of Vega-like stars”, Astronomy and Astrophysics, 490 (1): 297\u2013305, arXiv:0805.3936, Bibcode:2008A&A…490..297S, doi:10.1051\/0004-6361:200810260, S2CID\u00a015059920^ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev.\u00a0ed.). Cambridge, Massachusetts: Sky Pub. ISBN\u00a0978-1-931559-44-7.^ a b “IAU Catalog of Star Names”. Retrieved July 28, 2016.^ Hubrig, S.;  et\u00a0al. (June 2001), “Search for low-mass PMS companions around X-ray selected late B stars”, Astronomy and Astrophysics, 372: 152\u2013164, arXiv:astro-ph\/0103201, Bibcode:2001A&A…372..152H, doi:10.1051\/0004-6361:20010452, S2CID\u00a017507782^ “IAU Working Group on Star Names (WGSN)”. Retrieved May 22, 2016.^ “Bulletin of the IAU Working Group on Star Names, No. 1” (PDF). Retrieved July 28, 2016.^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) \u5929\u6587\u6559\u80b2\u8cc7\u8a0a\u7db2 2006 \u5e74 7 \u6708 2 \u65e5^ Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint\u00a0ed.). New York: Dover Publications Inc. p.\u00a0357. ISBN\u00a00-486-21079-0. Retrieved September 4, 2012.External links[edit]  "},{"@context":"http:\/\/schema.org\/","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"https:\/\/wiki.edu.vn\/en\/wiki24\/#breadcrumbitem","name":"Enzyklop\u00e4die"}},{"@type":"ListItem","position":2,"item":{"@id":"https:\/\/wiki.edu.vn\/en\/wiki24\/alpha-sagittarii-wikipedia\/#breadcrumbitem","name":"Alpha Sagittarii – Wikipedia"}}]}]