Coordinates: Sky map 05h 32m 00.4s, −00° 17′ 57″


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Orion Belt 2009-01-29.jpg
Orion's Belt (composed of the three brightest stars shown), Mintaka being the rightmost, on the west side
Observation data
Epoch J2000      Equinox J2000
Constellation Orion
δ Ori A (Aa1 + Aa2 + Ab)
Right ascension 05h 32m 00.40009s[1]
Declination −00° 17′ 56.7424″[1]
Apparent magnitude (V) 2.23[2] (2.50 + 3.90[3])
δ Ori B
Right ascension 05h 31m 58.745s[4]
Declination −00° 18′ 18.65″[4]
Apparent magnitude (V) 14.0[5]
HD 36485
Right ascension 05h 32m 00.406s[6]
Declination −00° 17′ 04.38″[6]
Apparent magnitude (V) 6.85[5]
Spectral type (O9.5II + B1V +B0IV[7]) + B3V[8]
U−B color index −1.05[2]
B−V color index −0.22[2]
Variable type Eclipsing binary[9]
Radial velocity (Rv)18.50 ± 0.5[10] km/s
Proper motion (μ) RA: 0.64±0.56[1] mas/yr
Dec.: −0.69±0.27[1] mas/yr
Parallax (π)4.71 ± 0.58 mas[1]
Distance1,200[7] ly
(380[7] pc)
Absolute magnitude (MV)−5.8[5]
δ Ori Aa1
Absolute magnitude (MV)−5.4[5]
δ Ori Aa2
Absolute magnitude (MV)−2.9[5]
δ Ori Ab
Absolute magnitude (MV)−4.2[5]
Primaryδ Ori Aa1
Companionδ Ori Aa2
Period (P)5.732436 days
Semi-major axis (a)43.1±1.7 R
Eccentricity (e)0.1133±0.0003
Inclination (i)76.5±0.2°
Periastron epoch (T)2,456,295.674±0.062
Argument of periastron (ω)
δ Ori Aa1
Mass24[7] M
Radius16.5[7] R
Luminosity190,000[7] L
Surface gravity (log g)3.37±0.15[7] cgs
Temperature29,500±500[7] K
Rotational velocity (v sin i)130±10[7] km/s
δ Ori Aa2
Mass8.4[7] M
Radius6.5[7] R
Luminosity16,000[7] L
Surface gravity (log g)3.9[7] cgs
Temperature25,600±3,000[7] K
Rotational velocity (v sin i)150±50[7] km/s
δ Ori Ab
Mass22.5[7] M
Radius10.4[7] R
Luminosity63,000[7] L
Surface gravity (log g)3.5±0.3[7] cgs
Temperature28,400±1,500[7] K
Rotational velocity (v sin i)220±20[7] km/s
δ Ori B
Radius0.77[11] R
Luminosity0.431[11] L
Temperature5,324[11] K
HD 36485
Mass~9[8] M
Radius5.7[12] R
Luminosity3,300[12] L
Surface gravity (log g)4.41[12] cgs
Temperature18,400[12] K
Other designations
Mintaka, δ Orionis, 34 Orionis, 88 G. Orionis, FK5 206, HIP 25930, ADS 4134, CCDM J05320-0018, WDS J05320-0018
Mintaka Aa: HD 36486, HR 1851, SAO 132220/132221, BD−00°983, GC 6847
Mintaka Ab: δ Orionis B, CCDM J05320-0018D, WDS J05320-0018Ab
δ Ori B: UCAC3 180-24383, CCDM J05320-0018B, WDS J05320-0018B
HD 36485: δ Orionis C, HR 1851, SAO 132221, BD−00°982, GC 6848, PLX 1261, CCDM J05320-0018C
Database references
δ Ori B
HD 36485

Mintaka /ˈmɪntəkə/,[13] designation Delta Orionis (δ Orionis, abbreviated Delta Ori, δ Ori) and 34 Orionis (34 Ori), is a multiple star system some 1,200 light-years from the Sun in the constellation of Orion. Together with Alnitak (Zeta Orionis) and Alnilam (Epsilon Orionis), the three stars form Orion's Belt, known by many names among ancient cultures. The star is located very close to the celestial equator. When Orion is near the meridian, Mintaka is the rightmost of the Belt's stars when viewed from the Northern Hemisphere facing south.


Delta Orionis is the star's Bayer designation, 34 Orionis its Flamsteed designation. The name Mintaka itself is derived from an Arabic term for 'belt': منطقة or manṭaqa.[14] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[15] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[16] included a table of the first two batches of names approved by the WGSN, which included Mintaka for this star. It is now so entered in the IAU Catalog of Star Names.[17]

Observational history[edit]

Location of δ Orionis (circled), as shown in a conventional star chart, that is looking at the southern or overhead sky from northern latitudes. The star generally appears on the left in the Southern Hemisphere looking at the northern sky.
Red circle.svg
Location of δ Orionis (circled), as shown in a conventional star chart, that is looking at the southern or overhead sky from northern latitudes. The star generally appears on the left in the Southern Hemisphere looking at the northern sky.

Mintaka is the westernmost of the three stars of Orion's belt. It is easily visible to the naked eye, one of the brightest stars in the sky, and has been known since antiquity.

Radial velocity measurements taken by Henri-Alexandre Deslandres in 1900 at Paris Observatory showed that Mintaka had a variable radial velocity and therefore was a spectroscopic binary.[18] His preliminary orbital period estimate of 1.92 days was shown to be incorrect in 1904 when Johannes Franz Hartmann using photographic plates taken at Potsdam Observatory showed that the orbital period was 5.7 days.[19] Hartmann also noticed that the calcium K line at 393.4 nanometres in the stellar spectrum did not share in the periodic displacements of the lines due to orbital motion of the star and theorized that there was a cloud in the line of sight to Mintaka that contained calcium. This was the first detection of the interstellar medium.[19]


A green band light curve for Delta Orionis, plotted from data published by Koch and Hrivnak (1981)[20]

δ Orionis is a multiple star system. There is a magnitude 7 star about 52 arcseconds away from the second-magnitude primary and a much fainter star in between. The system is designated WDS 05320-0018 in the Washington Double Star Catalog, with the 14th-magnitude companion listed as component B and the seventh-magnitude star as component C.[21]

The primary component is itself a triple system: a class-O9.5 bright giant and a class-B main-sequence star orbit every 5.73 days and exhibit shallow eclipses when the star dims about 0.2 of a magnitude,[9] and a B-class subgiant is resolved 0.26" away.[3] At the primary eclipse, the apparent magnitude (of the whole system) drops from 2.23 to 2.35, while it only drops to 2.29 at the secondary eclipse.[22]

The seventh-magnitude companion, HD 36485, is a chemically peculiar B-type main-sequence star and itself a spectroscopic binary with a faint A-type companion in a 30-day orbit. It has an unusual spectrum with H-alpha emission and unusually strong helium absorption lines. It has a strong magnetic field and a very slow rotational velocity that produces chemical stratification in its atmosphere, which leads to the unusual abundances seen in the spectrum.[8]

The 14th-magnitude companion is thought to be around the same distance and is a somewhat cooler and less luminous star than the Sun.[11]

Mintaka is surrounded by a cluster of faint stars, possibly part of the cluster surrounding σ Ori.[23]


The distance derived from the Hipparcos satellite parallax is 212±30 parsecs,[1] while spectroscopic distances, comparisons to similar stars, and cluster membership all suggest a value more than double that.[24] This type of unreconcilable discrepancy is not unique to Mintaka and the reasons for it have yet to be clarified.[7] In Gaia Data Release 2, components B and C are listed with parallaxes of 3.4531±0.0371 mas and 2.5727±0.0767 mas, respectively,[11][25] implying distances considerably further than the Hipparcos-derived value for the primary.[1]

Etymology and cultural significance[edit]

Mintaka was seen by astrologers as a portent of good fortune.[14]

Orion's Belt[edit]

The three belt stars were collectively known by many names in many cultures. Arabic terms include Al Nijād 'the Belt', Al Nasak 'the Line', Al Alkāt 'the Golden Grains or Nuts', and, in modern Arabic, Al Mīzān al Ḥakk 'the Accurate Scale Beam'. In Chinese mythology, they were also known as the Weighing Beam.[citation needed]

In Chinese, 參宿 (Shēn Sù), meaning Three Stars (asterism), refers to an asterism consisting of Mintaka, Alnilam, and Alnitak (Orion's Belt), with Betelgeuse, Bellatrix, Saiph and Rigel later added.[26] Consequently, the Chinese name for Mintaka is 參宿三 (Shēn Sù sān, English: the Third Star of Three Stars).[27] It is one of the western mansions of the White Tiger.


The USS Mintaka (AK-94) was a United States Navy Crater-class cargo ship named after the star.


  1. ^ a b c d e f g van 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. Vizier catalog entry
  2. ^ a b c Hoffleit, Dorrit; Jaschek, Carlos (1991). The Bright star catalogue (5th Revised ed.). New Haven, Conn.: Yale University Observatory.
  3. ^ a b c Tokovinin, A. A. (1997). "MSC - a catalogue of physical multiple stars". Astronomy and Astrophysics Supplement Series. 124: 75–84. Bibcode:1997A&AS..124...75T. doi:10.1051/aas:1997181.
  4. ^ a b Zacharias, N.; Finch, C. T.; Girard, T. M.; Henden, A.; Bartlett, J. L.; Monet, D. G.; Zacharias, M. I. (2012). "VizieR Online Data Catalog: UCAC4 Catalogue (Zacharias+, 2012)". VizieR On-line Data Catalog: I/322A. Bibcode:2012yCat.1322....0Z.
  5. ^ a b c d e f Harvin, James A.; Gies, Douglas R.; Bagnuolo, William G.; Penny, Laura R.; Thaller, Michelle L. (2002). "Tomographic Separation of Composite Spectra. VIII. The Physical Properties of the Massive Compact Binary in the Triple Star System HD 36486 (δ Orionis A)". Astrophysical Journal. 565 (2): 1216. arXiv:astro-ph/0110683. Bibcode:2002ApJ...565.1216H. doi:10.1086/324705. S2CID 118957476.
  6. ^ a b Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27. Bibcode:2000A&A...355L..27H. doi:10.1888/0333750888/2862.
  7. ^ a b c d e f g h i j k l m n o p q r s t u v Shenar, T.; Oskinova, L.; Hamann, W.-R.; Corcoran, M. F.; Moffat, A. F. J.; Pablo, H.; Richardson, N. D.; Waldron, W. L.; Huenemoerder, D. P.; Maíz Apellániz, J.; Nichols, J. S.; Todt, H.; Nazé, Y.; Hoffman, J. L.; Pollock, A. M. T.; Negueruela, I. (2015). "A Coordinated X-Ray and Optical Campaign of the Nearest Massive Eclipsing Binary, δ Orionis Aa. IV. A Multiwavelength, Non-LTE Spectroscopic Analysis". Astrophysical Journal. 809 (2): 135. arXiv:1503.03476. Bibcode:2015ApJ...809..135S. doi:10.1088/0004-637X/809/2/135. hdl:10045/59172. S2CID 14909574.
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  11. ^ a b c d e 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. Gaia DR2 record for this source at VizieR.
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  13. ^ Rumrill, H. B. (June 1936). "Star Name Pronunciation". Publications of the Astronomical Society of the Pacific. San Francisco, California. 48 (283): 139. Bibcode:1936PASP...48..139R. doi:10.1086/124681.
  14. ^ a b Allen, Richard Hinckley (1963) [1899]. Star-names and their meanings. New York, NY: Dover Publications. p. 314. ISBN 1-931559-44-9.
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  16. ^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
  17. ^ "IAU Catalog of Star Names". Retrieved 28 July 2016.
  18. ^ Deslandres, H. (1900). "Variable velocity in line of sight of delta Orionis. (Notes)". The Observatory. 23: 148. Bibcode:1900Obs....23..148D.
  19. ^ a b Hartmann, J. (1904). "Investigations on the spectrum and orbit of delta Orionis". Astrophysical Journal. 19: 268–286. Bibcode:1904ApJ....19..268H. doi:10.1086/141112.
  20. ^ Koch, R. H.; Hrivnak, B. J. (August 1981). "A photometric study of the close binary delta Orionis A". Astrophysical Journal. 248: 249–255. doi:10.1086/159148. Retrieved 14 July 2022.
  21. ^ Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
  22. ^ Zasche, P.; Wolf, M.; Hartkopf, W. I.; Svoboda, P.; Uhlař, R.; Liakos, A.; Gazeas, K. (2009). "A Catalog of Visual Double and Multiple Stars with Eclipsing Components". Astronomical Journal. 138 (2): 664. arXiv:0907.5172. Bibcode:2009AJ....138..664Z. doi:10.1088/0004-6256/138/2/664. S2CID 17089387.
  23. ^ Caballero, J. A.; Solano, E. (2008). "Young stars and brown dwarfs surrounding Alnilam (ɛ Orionis) and Mintaka (δ Orionis)". Astronomy and Astrophysics. 485 (3): 931. arXiv:0804.2184. Bibcode:2008A&A...485..931C. doi:10.1051/0004-6361:200809595. S2CID 16175953.
  24. ^ Corcoran, M. F.; Nichols, J. S.; Pablo, H.; Shenar, T.; Pollock, A. M. T.; Waldron, W. L.; Moffat, A. F. J.; Richardson, N. D.; Russell, C. M. P.; Hamaguchi, K.; Huenemoerder, D. P.; Oskinova, L.; Hamann, W.-R.; Nazé, Y.; Ignace, R.; Evans, N. R.; Lomax, J. R.; Hoffman, J. L.; Gayley, K.; Owocki, S. P.; Leutenegger, M.; Gull, T. R.; Hole, K. T.; Lauer, J.; Iping, R. C. (2015). "A Coordinated X-Ray and Optical Campaign of the Nearest Massive Eclipsing Binary, δ Orionis Aa. I. Overview of the X-Ray Spectrum". Astrophysical Journal. 809 (2): 132. arXiv:1507.05101. Bibcode:2015ApJ...809..132C. doi:10.1088/0004-637X/809/2/132. S2CID 17339779.
  25. ^ 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. Gaia DR2 record for this source at VizieR.
  26. ^ (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
  27. ^ (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]