Epoch J2000 Equinox J2000
|Right ascension||05h 32m 00.400s|
|Declination||−00° 17′ 56.74″|
|Apparent magnitude (V)||2.23 (3.2/3.3) / 6.85 / 14.0|
|Spectral type||O9.5 II + B0.5III|
|U−B color index||−1.05|
|B−V color index||−0.22|
|Variable type||Eclipsing binary|
|Radial velocity (Rv)||16 km/s|
|Proper motion (μ)||RA: 0.64 ± 0.56 mas/yr
Dec.: -0.69 ± 0.27 mas/yr
|Parallax (π)||4.71 ± 0.58 mas|
|Distance||approx. 690 ly
(approx. 210 pc)
|Absolute magnitude (MV)||−4.99|
|Surface gravity (log g)||3.5 cgs|
|Temperature||31,802 ± 418 K|
Mintaka is a star some 916 light years distant in the constellation Orion. It has a Bayer designation of Delta Orionis (δ Ori) and a Flamsteed designation of 34 Orionis. The name Mintaka comes from منطقة manṭaqa, which means "the belt" in Arabic. Together with Alnitak (Zeta Orionis) and Alnilam (Epsilon Orionis), the three stars make up the belt of Orion, known by many names among ancient cultures. When Orion is close to the meridian, Mintaka is the right-most of the belt's stars as seen by an observer in the Northern Hemisphere facing south.
Mintaka is actually a multiple star at the western end of Orion's belt, with a magnitude 7 star about 52 arcseconds away from the main component and an even fainter star in between. The main component itself is also double, consisting of a class B giant and a smaller but hotter class O. The stars orbit each other every 5.73 days. These two stars are both about 90,000 times as luminous as the Sun with a mass of some 20 solar masses.
Radial velocity measurements taken by Henri-Alexandre Deslandres at Paris Observatory showed that Mintaka had a variable radial velocity and therefore was a spectroscopic binary. 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. 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.
Etymology and cultural significance
Mintaka was also seen by astrologers as a portent of good fortune.
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 H•akk 'the Accurate Scale Beam'. In Chinese mythology they were also known as The Weighing Beam. The belt was also the Three Stars mansion (simplified Chinese: 参宿; traditional Chinese: 參宿; pinyin: Shēn Xiù), one of the Twenty-eight mansions of the Chinese constellations. It is one of the western mansions of the White Tiger.
In pre-Christian Scandinavia, the belt was known as Frigg's Distaff (Friggerock) or Freyja's distaff. Similarly Jacob's Staff and Peter's Staff were European biblical derived terms, as were the Three Magi, or the Three Kings. Väinämöinen's Scythe (Kalevala) and Kalevan Sword are terms from Finnish mythology.
The Seri people of northwestern Mexico call the three belt stars Hapj (a name denoting a hunter), which consists of three stars: Hap (mule deer), Haamoja (pronghorn), and Mojet (bighorn sheep). Hap is in the middle and has been shot by the hunter; its blood has dripped onto Tiburón Island.
In Spain and Portugal, this asterism is known as Las Tres Marías or As Três Marias, which stand for The Three Marys in Spanish and Portuguese respectively.
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