Alnitak is a triple star system in the constellation of Orion. It has the designations ζ Orionis, which is Latinised to Zeta Orionis and abbreviated Zeta Ori or ζ Ori, and 50 Orionis, abbreviated 50 Ori. The system is located at a distance of several hundred parsecs from the Sun and is one of the three main stars of Orion's Belt along with Alnilam and Mintaka.
The primary star, Alnitak Aa, is a hot blue supergiant with an absolute magnitude of −6.0 and is the brightest class O star in the night sky with a visual magnitude of +2.0. It has two companions—Ab and B, the latter known for the longest time and the former discovered recently, producing a combined magnitude for the trio of +1.77. The stars are members of the Orion OB1 association and the Collinder 70 [de] association.
Alnitak has been known since antiquity and, as a component of Orion's Belt, has been of widespread cultural significance. It was reported to be a double star by amateur German astronomer George K. Kunowsky in 1819.[11] Much more recently, in 1998, the bright primary was found by a team from the Lowell Observatory to have a close companion; this had been suspected from observations made with the Narrabri Stellar Intensity Interferometer in the 1970s.[12]
The stellar parallax derived from observations by the Hipparcos satellite imply a distance around 225 parsecs, but this does not take into account distortions caused by the multiple nature of the system and larger distances have been derived by many authors.[4]
Stellar system
Alnitak Aa compared to the Sun (to scale)
Alnitak is a triple star system at the eastern end of Orion's Belt, the second-magnitude primary having a 4th-magnitude companion nearly 3 arcseconds distant, in an orbit taking over 1,500 years.
The part called Alnitak A is itself a close binary, comprising the stars Alnitak Aa and Alnitak Ab.
The traditional name Alnitak, alternately spelled Al Nitak or Alnitah, is taken from the Arabic النطاق an-niṭāq, "the girdle".[11] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[13] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[14] included a table of the first two batches of names approved by the WGSN; which included Alnitak for the star ζ Orionis Aa. It is now so entered in the IAU Catalog of Star Names.[15]
The three belt stars were collectively known by many names in many cultures. Arabic terms include النجاد Al Nijād 'the Belt', النسك Al Nasak 'the Line', العلقات Al Alkāt 'the Golden Grains or Nuts' and, in modern Arabic, ميزان الحق Al Mīzān al Ḥaqq 'the Scale of Justice'. In Chinese mythology they were known as The Weighing Beam.[11]
^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. ISBN978-1-931559-44-7.
^ abcdeVan Leeuwen, F. (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.
^ abDucati, 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.
^ abcdefghijklmnopqrHummel, C. A.; Rivinius, T.; Nieva, M. -F.; Stahl, O.; Van Belle, G.; Zavala, R. T. (2013). "Dynamical mass of the O-type supergiant in ζ Orionis A". Astronomy & Astrophysics. 554: A52. arXiv:1306.0330. Bibcode:2013A&A...554A..52H. doi:10.1051/0004-6361/201321434. S2CID 53645495.
^Fabricius, C.; Høg, E.; Makarov, V. V.; Mason, B. D.; Wycoff, G. L.; Urban, S. E. (2002). "The Tycho double star catalogue". Astronomy and Astrophysics. 384 (1): 180–189. Bibcode:2002A&A...384..180F. doi:10.1051/0004-6361:20011822. ISSN 0004-6361.
^Kharchenko, N.V.; Scholz, R.-D.; Piskunov, A.E.; Röser, S.; Schilbach, E. (2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten. 328 (9): 889–896. arXiv:0705.0878. Bibcode:2007AN....328..889K. doi:10.1002/asna.200710776. ISSN 0004-6337. S2CID 119323941.
^"Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Retrieved 15 May 2017.
^Raassen, A. J. J.; Van Der Hucht, K. A.; Miller, N. A.; Cassinelli, J. P. (2008). "XMM-Newton observations of ζ Orionis (O9.7 Ib): A collisional ionization equilibrium model". Astronomy and Astrophysics. 478 (2): 513. arXiv:0803.0873. Bibcode:2008A&A...478..513R. doi:10.1051/0004-6361:20077891. S2CID 17601299.
^Buysschaert, B.; Neiner, C.; Ramiaramanantsoa, T.; Richardson, N. D.; David-Uraz, A.; Moffat, A. F. J. (2016). "Understanding the photometric variability of ζ OriAa". Second Brite-Constellation Science Conference: Small Satellites – Big Science. 5: 101. arXiv:1610.05625. Bibcode:2017sbcs.conf..101B.
^Blazère, A.; Neiner, C.; Tkachenko, A.; Bouret, J.-C.; Rivinius, Th. (2015). "The magnetic field of ζ Orionis A". Astronomy & Astrophysics. 582: A110. arXiv:1509.02773. Bibcode:2015A&A...582A.110B. doi:10.1051/0004-6361/201526855. S2CID 62800990.
^ abcRichard Hinckley Allen, Star-names and their meanings (1936), p. 314–15.
^ abHummel CA; White NM; Elias NM II; Hajian AR; Nordgren TE (2000). "ζ Orionis A Is a Double Star". The Astrophysical Journal. 540 (2): L91–L93. Bibcode:2000ApJ...540L..91H. doi:10.1086/312882.
^"IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
^"Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
^"IAU Catalog of Star Names". Retrieved 28 July 2016.
^(in Chinese)中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN978-986-7332-25-7.
^(in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 25 日
External links
"Alnitak 3". SolStation. Retrieved 2005-12-15.
NASA Astronomy Picture of the Day: Image of Alnitak (12 January 2010)
Alnitak on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images
alnitak, triple, star, system, constellation, orion, designations, orionis, which, latinised, zeta, orionis, abbreviated, zeta, orionis, abbreviated, system, located, distance, several, hundred, parsecs, from, three, main, stars, orion, belt, along, with, alni. Alnitak is a triple star system in the constellation of Orion It has the designations z Orionis which is Latinised to Zeta Orionis and abbreviated Zeta Ori or z Ori and 50 Orionis abbreviated 50 Ori The system is located at a distance of several hundred parsecs from the Sun and is one of the three main stars of Orion s Belt along with Alnilam and Mintaka AlnitakAlnitak in lower right and the Flame NebulaObservation dataEpoch J2000 Equinox J2000Constellation OrionPronunciation ae l ˈ n aɪ t ae k 1 Right ascension 05h 40m 45 52666s 2 Declination 01 56 34 2649 2 Apparent magnitude V 1 77 3 2 08 4 28 4 01 4 CharacteristicsSpectral type O9 5Iab B1IV B0III 4 U B color index 1 06 3 B V color index 0 11 A 0 20 B 5 AstrometryRadial velocity Rv 18 50 6 km sProper motion m RA 3 19 2 mas yr Dec 2 03 2 mas yrParallax p 4 43 0 64 mas 2 Distance1 260 180 ly 387 54 4 pc Absolute magnitude MV 6 0 3 9 4 1 4 Orbit 4 PrimaryAaCompanionAbPeriod P 2 687 3 7 0 dSemi major axis a 35 9 0 2 masEccentricity e 0 338 0 004Inclination i 139 3 0 6 Longitude of the node W 83 8 0 8 Periastron epoch T JD 2452 734 2 9 0Argument of periastron w secondary 204 2 1 2 Semi amplitude K1 primary 10 1 km sSemi amplitude K2 secondary 19 6 km sOrbit 7 PrimaryACompanionBPeriod P 1 508 6 yrSemi major axis a 2 728 Eccentricity e 0 07Inclination i 72 0 Longitude of the node W 155 5 Periastron epoch T 2 070 6Argument of periastron w secondary 47 3 DetailsAlnitak AaMass33 10 4 M Radius20 0 3 2 4 R Luminosity250 000 4 L Surface gravity log g 3 2 0 1 8 cgsTemperature29 500 1 000 4 KRotation6 67 days 9 Rotational velocity v sin i 110 10 4 km sAge6 4 4 MyrAlnitak AbMass14 3 4 M Radius7 3 1 0 4 R Luminosity32 000 4 L Temperature29 000 10 KAge7 2 4 MyrAlnitak BRotational velocity v sin i 350 4 km sAge 7 4 MyrOther designations126 G Orionis z Orionis 50 Orionis BD 02 1338 HIP 26727 SAO 132444 WDS J05407 0157A HD 37742 HR 1948B HD 37743 HR 1949Database referencesSIMBADABABThe primary star Alnitak Aa is a hot blue supergiant with an absolute magnitude of 6 0 and is the brightest class O star in the night sky with a visual magnitude of 2 0 It has two companions Ab and B the latter known for the longest time and the former discovered recently producing a combined magnitude for the trio of 1 77 The stars are members of the Orion OB1 association and the Collinder 70 de association Contents 1 Observational history 2 Stellar system 3 Etymology and cultural significance 3 1 Orion s Belt 4 Namesakes 5 See also 6 References 7 External linksObservational history Edit Orion s Belt with Alnitak on the left Alnitak has been known since antiquity and as a component of Orion s Belt has been of widespread cultural significance It was reported to be a double star by amateur German astronomer George K Kunowsky in 1819 11 Much more recently in 1998 the bright primary was found by a team from the Lowell Observatory to have a close companion this had been suspected from observations made with the Narrabri Stellar Intensity Interferometer in the 1970s 12 The stellar parallax derived from observations by the Hipparcos satellite imply a distance around 225 parsecs but this does not take into account distortions caused by the multiple nature of the system and larger distances have been derived by many authors 4 Stellar system Edit Alnitak Aa compared to the Sun to scale Alnitak is a triple star system at the eastern end of Orion s Belt the second magnitude primary having a 4th magnitude companion nearly 3 arcseconds distant in an orbit taking over 1 500 years The part called Alnitak A is itself a close binary comprising the stars Alnitak Aa and Alnitak Ab Alnitak Aa is a blue supergiant of spectral type O9 5Iab with an absolute magnitude of 6 0 and an apparent magnitude of 2 0 It is estimated as being up to 33 times as massive as the Sun and a diameter 20 times greater It is some 21 000 times brighter than the Sun with a surface brightness luminance some 500 times greater It is the brightest star of class O in the night sky Alnitak Ab is a blue subgiant of spectral type B1IV with an absolute magnitude of 3 9 and an apparent magnitude of 4 3 discovered in 1998 12 A fourth star 9th magnitude Alnitak C has not been confirmed to be part of the Aa Ab B group and may simply lie along the line of sight The Alnitak system is bathed in the nebulosity of IC 434 Etymology and cultural significance Editz Orionis Latinised as Zeta Orionis is the star system s Bayer designation and 50 Orionis its Flamsteed designation The traditional name Alnitak alternately spelled Al Nitak or Alnitah is taken from the Arabic النطاق an niṭaq the girdle 11 In 2016 the International Astronomical Union organized a Working Group on Star Names WGSN 13 to catalog and standardize proper names for stars The WGSN s first bulletin of July 2016 14 included a table of the first two batches of names approved by the WGSN which included Alnitak for the star z Orionis Aa It is now so entered in the IAU Catalog of Star Names 15 Orion s Belt Edit Main article Orion s Belt The three belt stars were collectively known by many names in many cultures Arabic terms include النجاد Al Nijad the Belt النسك Al Nasak the Line العلقات Al Alkat the Golden Grains or Nuts and in modern Arabic ميزان الحق Al Mizan al Ḥaqq the Scale of Justice In Chinese mythology they were known as The Weighing Beam 11 The belt was also the Three Stars mansion simplified Chinese 参宿 traditional Chinese 參宿 pinyin Shen Xiu one of the twenty eight mansions of the Chinese constellations It is one of the western mansions of the White Tiger In Chinese 參宿 Shen Xiu meaning Three Stars asterism refers to an asterism consisting of Alnitak Alnilam and Mintaka Orion s Belt with Betelgeuse Bellatrix Saiph and Rigel later added 16 Consequently the Chinese name for Alnitak is 參宿一 Shen Xiu yi English the First Star of Three Stars 17 It is one of the western mansions of the White Tiger Namesakes EditThe USS Alnitah was a U S Navy Crater class cargo ship named after the star See also EditFlame NebulaReferences Edit 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 2007 Validation of the new Hipparcos reduction Astronomy and Astrophysics 474 2 653 664 arXiv 0708 1752 Bibcode 2007A amp A 474 653V doi 10 1051 0004 6361 20078357 S2CID 18759600 a b 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 a b c d e f g h i j k l m n o p q r Hummel C A Rivinius T Nieva M F Stahl O Van Belle G Zavala R T 2013 Dynamical mass of the O type supergiant in z Orionis A Astronomy amp Astrophysics 554 A52 arXiv 1306 0330 Bibcode 2013A amp A 554A 52H doi 10 1051 0004 6361 201321434 S2CID 53645495 Fabricius C Hog E Makarov V V Mason B D Wycoff G L Urban S E 2002 The Tycho double star catalogue Astronomy and Astrophysics 384 1 180 189 Bibcode 2002A amp A 384 180F doi 10 1051 0004 6361 20011822 ISSN 0004 6361 Kharchenko N V Scholz R D Piskunov A E Roser S Schilbach E 2007 Astrophysical supplements to the ASCC 2 5 Ia Radial velocities of 55000 stars and mean radial velocities of 516 Galactic open clusters and associations Astronomische Nachrichten 328 9 889 896 arXiv 0705 0878 Bibcode 2007AN 328 889K doi 10 1002 asna 200710776 ISSN 0004 6337 S2CID 119323941 Sixth Catalog of Orbits of Visual Binary Stars United States Naval Observatory Retrieved 15 May 2017 Raassen A J J Van Der Hucht K A Miller N A Cassinelli J P 2008 XMM Newton observations of z Orionis O9 7 Ib A collisional ionization equilibrium model Astronomy and Astrophysics 478 2 513 arXiv 0803 0873 Bibcode 2008A amp A 478 513R doi 10 1051 0004 6361 20077891 S2CID 17601299 Buysschaert B Neiner C Ramiaramanantsoa T Richardson N D David Uraz A Moffat A F J 2016 Understanding the photometric variability of z OriAa Second Brite Constellation Science Conference Small Satellites Big Science 5 101 arXiv 1610 05625 Bibcode 2017sbcs conf 101B Blazere A Neiner C Tkachenko A Bouret J C Rivinius Th 2015 The magnetic field of z Orionis A Astronomy amp Astrophysics 582 A110 arXiv 1509 02773 Bibcode 2015A amp A 582A 110B doi 10 1051 0004 6361 201526855 S2CID 62800990 a b c Richard Hinckley Allen Star names and their meanings 1936 p 314 15 a b Hummel CA White NM Elias NM II Hajian AR Nordgren TE 2000 z Orionis A Is a Double Star The Astrophysical Journal 540 2 L91 L93 Bibcode 2000ApJ 540L 91H doi 10 1086 312882 IAU Working Group on Star Names WGSN Retrieved 22 May 2016 Bulletin of the IAU Working Group on Star Names No 1 PDF Retrieved 28 July 2016 IAU Catalog of Star Names Retrieved 28 July 2016 in Chinese 中國星座神話 written by 陳久金 Published by 台灣書房出版有限公司 2005 ISBN 978 986 7332 25 7 in Chinese AEEA Activities of Exhibition and Education in Astronomy 天文教育資訊網 2006 年 5 月 25 日External links Edit Alnitak 3 SolStation Retrieved 2005 12 15 NASA Astronomy Picture of the Day Image of Alnitak 12 January 2010 Alnitak on WikiSky DSS2 SDSS GALEX IRAS Hydrogen a X Ray Astrophoto Sky Map Articles and images Portals Astronomy Stars Outer space Retrieved from https en wikipedia org w index php title Alnitak amp oldid 1125806665, wikipedia, wiki, book, books, library,
