Mintaka , designation Delta Orionis (δ Orionis, abbreviated Delta Ori, δ Ori) and 34 Orionis (34 Ori), is a multiple

star system A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. A large group of stars bound by gravitation is generally called a '' star cluster'' or ''galaxy'', although, broadly speaking ...

some 1,200

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distance, astronomical distances and is equivalent to about 9.46 Orders of magnitude (numbers)#1012, trillion kilometers (), or 5.88 ...

s from the Sun in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the earliest 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 The celestial equator is the great circle of the imaginary celestial sphere on the same plane as the equator of Earth. This plane of reference bases the equatorial coordinate system. In other words, the celestial equator is an abstract proj ...

. When Orion is near the meridian, Mintaka is the rightmost of the Belt's stars when viewed from the

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...

facing

south South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both east and west. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþa ...

Nomenclature

''Delta Orionis'' is the star's

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars ...

, ''34 Orionis'' its

Flamsteed designation A Flamsteed designation is a combination of a number and constellation name that uniquely identifies most naked eye stars in the modern constellations visible from southern England. They are named for John Flamsteed who first used them while co ...

. The name ''Mintaka'' itself is derived from an

Arabic Arabic (, ' ; , ' or ) is a Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walter ...

term for 'belt': منطقة or ''manṭaqa''. In 2016, the

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...

organized a

Working Group on Star Names The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education ...

(WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 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.

Observational history

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 This is a list of stars arranged by their apparent magnitude – their brightness as observed from Earth. It includes all stars brighter than magnitude +2.50 in visible light, measured using a ''V''-band filter in the UBV photometric system. St ...

in the sky, and has been known since antiquity.

Radial velocity The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the rate of change of the distance or range between the two points. It is equivalent to the vector projection ...

measurements taken by Henri-Alexandre Deslandres in 1900 at

Paris Observatory The Paris Observatory (french: Observatoire de Paris ), a research institution of the Paris Sciences et Lettres University, is the foremost astronomical observatory of France, and one of the largest astronomical centers in the world. Its histo ...

showed that Mintaka had a variable radial velocity and therefore was a

spectroscopic binary A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in w ...

. His preliminary

orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting pla ...

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 Astronomical spectroscopy is the study of astronomy using the techniques of spectroscopy to measure the spectrum of electromagnetic radiation, including visible light, ultraviolet, X-ray, infrared and radio waves that radiate from stars and othe ...

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 Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar ...

. This was the first detection of the

interstellar medium In astronomy, the interstellar medium is the matter and radiation that exist in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstella ...

System

δ Orionis is a

multiple star system A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. A large group of stars bound by gravitation is generally called a ''star cluster'' or ''galaxy'', although, broadly speaking ...

. There is a magnitude 7 star about 52

arcseconds A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The ...

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 The Washington Double Star Catalog, or WDS, is a catalog of double stars, maintained at the United States Naval Observatory. The catalog contains positions, magnitudes, proper motions and spectral types and has entries for (as of June 2017) 141,7 ...

, with the 14th-magnitude companion listed as component B and the seventh-magnitude star as component C. 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, and a B-class

subgiant A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution ...

is resolved 0.26" away. 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. The seventh-magnitude companion, HD 36485, is a chemically peculiar

B-type main-sequence star A B-type main-sequence star (B V) is a main-sequence ( hydrogen-burning) star of spectral type B and luminosity class V. These stars have from 2 to 16 times the mass of the Sun and surface temperatures between 10,000 and 30,000 K. B-type st ...

and itself a spectroscopic binary with a faint A-type companion in a 30-day orbit. It has an unusual spectrum with

H-alpha H-alpha (Hα) is a specific deep-red visible spectral line A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared wit ...

emission and unusually strong helium

absorption line A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to ident ...

s. 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. The 14th-magnitude companion is thought to be around the same distance and is a somewhat cooler and less luminous star than the Sun. Mintaka is surrounded by a cluster of faint stars, possibly part of the cluster surrounding σ Ori.

Distance

The distance derived from the ''

Hipparcos ''Hipparcos'' was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial ob ...

'' satellite parallax is , while spectroscopic distances, comparisons to similar stars, and cluster membership all suggest a value more than double that. This type of unreconcilable discrepancy is not unique to Mintaka and the reasons for it have yet to be clarified. In

Gaia Data Release 2 The ''Gaia'' catalogues are star catalogues created using the results obtained by ''Gaia'' space telescope. The catalogues are released in stages that will contain increasing amounts of information; the early releases also miss some stars, especi ...

, components B and C are listed with parallaxes of and , respectively, implying distances considerably further than the ''Hipparcos''-derived value for the primary.

Etymology and cultural significance

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

Orion's Belt

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 Chinese mythology () is mythology that has been passed down in oral form or recorded in literature in the geographic area now known as Greater China. Chinese mythology includes many varied myths from regional and cultural traditions. Much of ...

, they were also known as the Weighing Beam. In Chinese, (), meaning '' Three Stars (asterism)'', refers to an asterism consisting of Mintaka, Alnilam, and Alnitak (Orion's Belt), with

Betelgeuse Betelgeuse is a red supergiant of spectral type M1-2 and one of the largest stars visible to the naked eye. It is usually the tenth-brightest star in the night sky and, after Rigel, the second-brightest in the constellation of O ...

Bellatrix Bellatrix is the third-brightest star in the constellation of Orion, positioned 5° west of the red supergiant Betelgeuse (Alpha Orionis). It has the Bayer designation γ Orionis, which is Latinized to Gamma Orionis. With a slightly v ...

Saiph Saiph , designation Kappa Orionis (κ Orionis, abbreviated Kappa Ori, κ Ori) and 53 Orionis (53 Ori), is the sixth-brightest star in the constellation of Orion. Of the four bright stars that compose Orion's main quadrangle, it is the sta ...

and

Rigel Rigel is a blue supergiant star in the constellation of Orion. It has the Bayer designation β Orionis, which is Latinized to Beta Orionis and abbreviated Beta Ori or β Ori. Rigel is the brightest and most massive componentand ...

later added. Consequently, the

Chinese name Chinese names or Chinese personal names are names used by individuals from Greater China and other parts of the Chinese-speaking world throughout East and Southeast Asia (ESEA). In addition, many names used in Japan, Korea and Vietnam are ofte ...

for Mintaka is (, en, the Third Star of Three Stars).
AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 25 日
/ref> It is one of the western mansions of the

White Tiger The white tiger or bleached tiger is a leucistic pigmentation variant of the Mainland tiger. It is reported in the wild from time to time in the Indian states of Madhya Pradesh, Assam, West Bengal, Bihar, Odisha, in the Sunderbans region and ...

Namesakes

The USS ''Mintaka'' (AK-94) was a

United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

''Crater''-class cargo ship named after the star.

References

External links

*
Mintaka page constellationsofwords.com

Mintaka page at Astrostudio

Mintaka with HD 36485 visible at 12 noon and star C at 4 o'clock
{{DEFAULTSORT:Mintaka Orionis, Delta Spectroscopic binaries Eclipsing binaries O-type bright giants B-type main-sequence stars Orion (constellation) Stars named from the Arabic language Orionis, 34

1851 Events January–March * January 11 – Hong Xiuquan officially begins the Taiping Rebellion. * January 15 – Christian Female College, modern-day Columbia College, receives its charter from the Missouri General Assembly. ...

036486 Triple star systems Durchmusterung objects 025930