| 词条 | Alnitak |
| 释义 |
| image= | caption=Alnitak (in lower right) and the Flame Nebula }}{{Starbox observe | epoch=J2000 | ra={{RA|05|40|45.52666}}[1] | dec={{DEC|−01|56|34.2649}}[1] | appmag_v=1.77[2] {{nowrap|(2.08 + 4.28 + 4.01[4])}} | constell=Orion }}{{Starbox character | class=O9.5Iab + B1IV + B0III[3] | b-v=−0.11 (A) −0.20 (B)[4] | | u-b=−1.06[2] | variable= }}{{Starbox astrometry | radial_v=18.50[5] | prop_mo_ra=3.19[1] | prop_mo_dec=2.03[1] | parallax=4.43 | p_error=0.64 | parallax_footnote=[1] | dist_ly={{cvt|387|±|54|pc|ly|disp=number}} | dist_pc=387 ± 54[3] | absmag_v=−6.0 / −3.9 / −4.1[3] }}{{Starbox orbit | reference = [3] | primary = Aa | name = Ab | period_unitless = 2687.3 ± 7.0 d | axis_unitless = 35.9 ± 0.2 m | eccentricity = 0.338 ± 0.004 | inclination = 139.3 ± 0.6 | node = 83.8 ± 0.8 | periastron = JD 2452734.2 ± 9.0 | periarg = 204.2 ± 1.2 | k1 = 10.1 | k2 = 19.6 }}{{Starbox orbit | reference = [6] | primary=A | name=B | period=1508.6 | axis=2.728 | eccentricity=0.07 | inclination=72.0 | node=155.5 | periarg=47.3 | periastron=2070.6 }}{{Starbox detail | component1=Alnitak Aa | mass=33 ± 10[3] | radius=20.0 ± 3.2[3] | luminosity=250,000[3] | gravity = 3.2 ± 0.1[7] | temperature = 29,500 ± 1000[3] | rotational_velocity = 110 ± 10[3] | rotation = 6.67 days[8] | age_myr = 6.4[3] | component2 = Alnitak Ab | mass2 = 14 ± 3[3] | radius2 = 7.3 ± 1.0[3] | luminosity2=32,000[3] | temperature2 = 29,000[9] | gravirt = 4.0[9] | age_myr2=7.2[3] }}{{Starbox detail | no_heading=y | component1=Alnitak B | mass= | radius= | luminosity= | temperature= | rotational_velocity=350[3] | age_myr=~7[3] }}{{Starbox catalog | names=ζ Orionis, 50 Orionis, 126 G. Orionis, BD−02°1338, SAO 132444, HIP 26727, TD1 5127, WDS J05407-0157 | component1=A | names1=HR 1948, HD 37742 | component2=B | names2=HR 1949, HD 37743 }}{{Starbox reference | Simbad=Alnitak | sn=AB | Simbad2=zet+Ori+A | sn2=A | Simbad3=zet+Ori+B | sn3=B }}{{Starbox end}} Alnitak, also designated ζ Orionis (Latinised to Zeta Orionis, abbreviated Zeta Ori, ζ Ori) and 50 Orionis (abbreviated 50 Ori), is a triple star system several hundred parsecs from the Sun in the constellation of Orion. It 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 bluish 4th magnitude companions, one finely resolved and one only detected interferometrically and spectroscopically, producing a combined magnitude for the trio of +1.77. The stars are members of the Orion OB1 association and the {{ill|Collinder 70|de|vertical-align=sup}} association. Observational historyAlnitak 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.[32] 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.[33] 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.[3] Stellar systemAlnitak is a triple star system at the eastern end of Orion's belt, the second magnitude primary having a 4th magnitude companion nearly 3 arc-seconds 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.[10] 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 significanceζ 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-niṭāq, "the girdle".[11] 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 Alnitak for the star ζ Orionis Aa. It is now so entered in the IAU Catalog of Star Names.[14] Orion's Belt{{Main|Orion's Belt}}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 Accurate Scale Beam'. In Chinese mythology they were known as The Weighing Beam.[11] The belt was also the Three Stars mansion ({{zh|t=參宿|s=参宿|p=Shēn Xiù}}), one of the Twenty-eight mansions of the Chinese constellations. It is one of the western mansions of the White Tiger. In Chinese, {{lang|zh|參宿}} ({{lang|zh-Latn|Shēn Xiù}}), meaning Three Stars (asterism), refers to an asterism consisting of Alnitak, Alnilam, Mintaka (Orion's Belt) with Betelgeuse, Bellatrix, Saiph and Rigel[15] Consequently, Alnitak are known as {{lang|zh|參宿一}} ({{lang|zh-Latn|Shēn Xiù yī}}, {{lang-en|the First Star of Three Stars}}).[16] It is one of the western mansions of the White Tiger. NamesakesThe USS Alnitah was a United States Navy Crater-class cargo ship named after the star. See also
References1. ^1 2 3 4 {{cite journal|bibcode=2007A&A...474..653V|title=Validation of the new Hipparcos reduction|journal=Astronomy and Astrophysics|volume=474|issue=2|pages=653|author1=Van Leeuwen|first1=F.|date=2007|doi=10.1051/0004-6361:20078357|arxiv = 0708.1752 }} 2. ^1 {{cite journal|bibcode=2002yCat.2237....0D|title=VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system|journal=CDS/ADC Collection of Electronic Catalogues|volume=2237|pages=0|author1=Ducati|first1=J. R.|date=2002}} 3. ^1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 {{Cite journal | doi = 10.1051/0004-6361/201321434| title = Dynamical mass of the O-type supergiant in ζ Orionis A| journal = Astronomy & Astrophysics| volume = 554| pages = A52| date = 2013| last1 = Hummel | first1 = C. A.| last2 = Rivinius | first2 = T. | last3 = Nieva | first3 = M. -F. | last4 = Stahl | first4 = O.| last5 = Van Belle | first5 = G.| last6 = Zavala | first6 = R. T.|arxiv = 1306.0330 |bibcode = 2013A&A...554A..52H }} 4. ^{{cite journal|last1=Fabricius|first1=C.|last2=Høg|first2=E.|last3=Makarov|first3=V. V.|last4=Mason|first4=B. D.|last5=Wycoff|first5=G. L.|last6=Urban|first6=S. E.|title=The Tycho double star catalogue|journal=Astronomy and Astrophysics|volume=384|issue=1|date=2002|pages=180–189|issn=0004-6361|doi=10.1051/0004-6361:20011822|bibcode = 2002A&A...384..180F }} 5. ^{{cite journal|last1=Kharchenko|first1=N.V.|last2=Scholz|first2=R.-D.|last3=Piskunov|first3=A.E.|last4=Röser|first4=S.|last5=Schilbach|first5=E.|title=Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ∼55000 stars and mean radial velocities of 516 Galactic open clusters and associations|journal=Astronomische Nachrichten|volume=328|issue=9|date=2007|pages=889–896|issn=0004-6337|doi=10.1002/asna.200710776|arxiv = 0705.0878 |bibcode = 2007AN....328..889K }} 6. ^{{cite web|url=http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/wds/orb6|title=Sixth Catalog of Orbits of Visual Binary Stars|publisher=United States Naval Observatory|accessdate=15 May 2017}} 7. ^{{cite journal|doi=10.1051/0004-6361:20077891|title=XMM-Newton observations of ζ Orionis (O9.7 Ib): A collisional ionization equilibrium model|journal=Astronomy and Astrophysics|volume=478|issue=2|pages=513|year=2008|last1=Raassen|first1=A. J. J.|last2=Van Der Hucht|first2=K. A.|last3=Miller|first3=N. A.|last4=Cassinelli|first4=J. P.|bibcode=2008A&A...478..513R|arxiv = 0803.0873 }} 8. ^{{cite arxiv|title=Understanding the photometric variability of ζ OriAa|author1=Buysschaert, B.|author2=Neiner, C.|author3=Ramiaramanantsoa, T.|author4=Richardson, N. D.|author5=David-Uraz, A.|author6=Moffat, A. F. J.|eprint=1610.05625|date=2016|class=astro-ph.SR}} 9. ^1 {{cite journal|bibcode=2015A&A...582A.110B|arxiv=1509.02773|title=The magnetic field of ζ Orionis A|journal=Astronomy & Astrophysics|volume=582|pages=A110|author1=Blazère|first1=A.|last2=Neiner|first2=C.|last3=Tkachenko|first3=A.|last4=Bouret|first4=J.-C.|last5=Rivinius|first5=Th.|year=2015|doi=10.1051/0004-6361/201526855}} 10. ^1 {{cite journal |author=Hummel CA |author2=White NM |author3=Elias NM II |author4=Hajian AR |author5=Nordgren TE|date= 2000|title=ζ Orionis A Is a Double Star |journal=The Astrophysical Journal |volume=540 |issue=2 |pages=L91–L93 |doi=10.1086/312882 |bibcode=2000ApJ...540L..91H}} 11. ^1 2 Richard Hinckley Allen, Star-names and their meanings (1936), p. 314-15. 12. ^{{cite web | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN)|accessdate=22 May 2016}} 13. ^{{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 |accessdate=28 July 2016}} 14. ^{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |accessdate=28 July 2016}} 15. ^{{zh icon}} 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}}. 16. ^{{zh icon}} AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 25 日 External links
12 : Bayer objects|O-type supergiants|B-type giants|Triple star systems|Orion (constellation)|Stars with proper names|Durchmusterung objects|Henry Draper Catalogue objects|Hipparcos objects|Flamsteed objects|Gould objects|HR objects |
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