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

Mintaka

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For other uses, see Mintaka (disambiguation).
Mintaka
File: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]
Characteristics
A
Spectral type O9.5II + B1V +B0IV[7]
U−B color index −1.05[2]
B−V color index −0.22[2]
Variable type Eclipsing binary[8]
HD 36485
Spectral type B3V + A0V[9]
U−B color index −0.71[10]
B−V color index −0.16[10]
Astrometry
Radial velocity (Rv)18.50±0.5[11] 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]
HD 36485
Proper motion (μ) RA: +1.523[12] mas/yr
Dec.: −1.653[12] mas/yr
Parallax (π)2.6245±0.0538 mas[12]
Distance1,240 ± 30 ly
(381 ± 8 pc)
Orbit[13]
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)
(secondary)		141.3±0.2°
Orbit[9]
Primaryδ Ori Aa1/2
Companionδ Ori Ab
Period (P)53,839 days
Semi-major axis (a)20,038 R☉
Eccentricity (e)0.5886±0.016
Inclination (i)104.7±0.4°
Longitude of the node (Ω)122.4±0.5°
Periastron epoch (T)2,458,773.2±0.1
Argument of periastron (ω)
(secondary)		259±2°
Details
δ Ori Aa1
Mass17.8[9] M☉
Radius13.1[9] R☉
Luminosity190,000[7] L☉
Surface gravity (log g)3.55±0.05[9] cgs
Temperature31,400±1,000[9] K
Rotational velocity (v sin i)114±20[9] km/s
δ Ori Aa2
Mass8.518[9] M☉
Radius4.168[9] R☉
Luminosity16,000[7] L☉
Surface gravity (log g)3.48±0.06[9] cgs
Temperature25,442±1,500[9] K
Rotational velocity (v sin i)89±15[9] km/s
δ Ori Ab
Mass8.787[9] M☉
Radius12.045[9] R☉
Luminosity63,000[7] L☉
Surface gravity (log g)3.64±0.05[9] cgs
Temperature30,250±1,000[9] K
Rotational velocity (v sin i)216±25[9] km/s
δ Ori B
Radius0.77[14] R☉
Luminosity0.431[14] L☉
Temperature5,324[14] K
HD 36485
Mass6-11[15] M☉
Radius5.7[16] R☉
Luminosity3,300[16] L☉
Surface gravity (log g)4.41[16] cgs
Temperature18,400[16] 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: 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
SIMBADdata
δ Ori B
HD 36485

Mintaka /ˈmɪntəkə/,[17] designation Delta Orionis (δ Orionis, abbreviated Delta Ori, δ Ori) and 34 Orionis (34 Ori), is a quintuple 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.

The five stars form a hierarchy:[9]

  • Delta Ori A
    • Delta Ori Aa, an eclipsing binary with an orbital period of 5.7 days
      • Delta Ori Aa1, a single star
      • Delta Ori Aa2, a single star
    • Delta Ori Ab, which orbits Aa at a distance, with an orbital period of 152 years
  • Delta Ori B, a single star not physically associated with the system
  • Delta Ori C, a binary star with an orbital period of 30 days, also known as HD 36485
    • Delta Ori Ca, a single star
    • Delta Ori Cb, a single star

"Mintaka" may also be used as the base name, e.g. "Mintaka C" for δ Ori C.

Nomenclature

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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.[18] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[19] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[20] 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.[21]

Observational history

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Location of δ Orionis (circled), as shown in a conventional star chart with north up

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.[22] 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.[23] 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.[23]

System

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Aa1
Period = 5.7 d
Aa2
Period = 152 yr
Ab
52″ separation
Ca
Period = 30 d
Cb

Hierarchy of orbits in the system[9]

File:DeltaOriLightCurve.png
A green band light curve for Delta Orionis, plotted from data published by Koch and Hrivnak (1981)[24]

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.[25]

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,[8] 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.[26]

The outer star of the triple system orbits the inner pair once every 53,839 days (147.40 yr). The orbit is quite eccentric, with the separation varying between 8,244 solar radii (38.34 au) and 31,832 solar radii (148.03 au).[9]

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.[15]

The 14th-magnitude companion, δ Orionis B, is thought to be closer than the rest of the system and not physically associated with it.[27] It is likely to be a K-type main sequence star.[9]

Mintaka is surrounded by a cluster of faint stars, possibly part of the cluster surrounding σ Ori.[28]

Distance

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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.[13] 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 3, component C is listed with a parallax of 2.6245±0.0538 mas,[12] consistent with the distances derived by other methods but disagreeing with the Hipparcos-derived value for the primary.[1]

The Gaia DR3 parallax for component B is 3.5002″±0.0119″, strongly suggesting it is considerably closer than the other members of the system and merely a chance alignment.[27] At that distance it is likely to be a K-type main sequence star.[9]

Etymology and cultural significance

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Mintaka was seen by astrologers as a portent of good fortune.[18]

Orion's Belt

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Main article: Orion's Belt
File:Dunhuang Star Atlas - Orion.jpg
Dunhuang Star Atlas – Orion

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 Xiù), 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.[29] Consequently, the Chinese name for Mintaka is 參宿三 (Shēn Xiù Sān, English: the Third Star of Three Stars).[30] It is one of the western mansions of the White Tiger.

Namesakes

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

References

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  1. ^ a b c d e f g Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value). Vizier catalog entry
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  10. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  11. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  12. ^ a b c d Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value). Gaia DR3 record for this source at VizieR.
  13. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  14. ^ a b c Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value). Gaia DR2 record for this source at VizieR.
  15. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  16. ^ a b c d Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  17. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  18. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  19. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
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  22. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  23. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  24. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  25. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  26. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  27. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value). Gaia DR3 record for this source at VizieR.
  28. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  29. ^ (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, Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  30. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 25 日 Archived 2011-07-16 at the Wayback Machine
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