Zeta Orionis
Encyclopedia
Zeta Orionis (ζ Ori), traditionally known as Alnitak , is a triple star
Multiple star
A multiple star consists of three or more stars which appear from the Earth to be close to one another in the sky. This may result from the stars being physically close and gravitationally bound to each other, in which case it is physical, or this closeness may be merely apparent, in which case...
some 800 light years distant in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Orion
Orion (constellation)
Orion, often referred to as The Hunter, is a prominent constellation located on the celestial equator and visible throughout the world. It is one of the most conspicuous, and most recognizable constellations in the night sky...
. It is part of Orion's Belt
Orion's Belt
The term Orion's Belt or the Belt of Orion may refer to:* Orion's Belt, an asterism consisting of three bright stars in a row in the constellation Orion* Orion's Belt, a 1985 film* Orion's Belt, a browser game...
along with Delta Orionis
Delta Orionis
Delta Orionis , traditionally known as Mintaka , is a star some 900 light years distant in the constellation Orion. Together with Zeta Orionis and Epsilon Orionis , the three stars make up the belt of Orion, known by many names across many ancient cultures...
(Mintaka) and Epsilon Orionis
Epsilon Orionis
Alnilam is a large blue supergiant star in the constellation of Orion. Its Flamsteed designation is 46 Orionis....
(Alnilam).
The primary star is a hot blue supergiant
Blue supergiant
Blue supergiants are supergiant stars of spectral type O or B.They are extremely hot and bright, with surface temperatures of 30,000-50,000 K. They typically have 10 to 50 solar masses on the Hertzsprung-Russell diagram, and can have radii up to about 25 solar radii...
with an absolute magnitude of -5.25, and is the brightest class O star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
in the night sky with a visual magnitude of +2.04. It has two bluish 4th magnitude companions, producing a combined magnitude for the trio of +1.72. The stars are members of the Orion OB1
Orion OB1 Association
The Orion OB1 stellar association is a contingent group of several dozen hot giant stars of spectral types O and B. Associated are thousands of lower-mass stars, and a number of protostars. It is part of the larger Orion Molecular Cloud Complex...
association and the Collinder 70 association.
Observation history
Alnitak 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. KunowskyGeorge K. Kunowsky
Georg Karl Friedrich Kunowsky was a German lawyer who was also a talented amateur astronomer.He made observations of Mars with an 11 cm achromatic refractor telescope made by Joseph von Fraunhofer, which was one of the first times that achromatic refractors were used for planetary...
in 1819. Much more recently, in 1998, the bright primary was found by a team from the Lowell Observatory
Lowell Observatory
Lowell Observatory is an astronomical observatory in Flagstaff, Arizona. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark in 1965....
to have a close companion; this had been suspected from observations made with the Narrabri Stellar Intensity Interferometer
Narrabri Stellar Intensity Interferometer
The Narrabri Stellar Intensity Interferometer was the first astronomical instrument to measure the diameters of a large number of stars at visible wavelengths. It was designed by Robert Hanbury Brown, who received the Hughes Medal in 1971 for this work...
in the 1970s. Initially thought to be around 1500 light years distant, the Alnitak system's distance was determined to be roughly half that (700 l.y.) via measurement of its stellar parallax
Parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines. The term is derived from the Greek παράλλαξις , meaning "alteration"...
by the Hipparcos
Hipparcos
Hipparcos was a scientific mission of the European Space Agency , launched in 1989 and operated between 1989 and 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial objects on the sky...
satellite.
System
Supergiant
Supergiants are among the most massive stars. They occupy the top region of the Hertzsprung-Russell diagram. In the Yerkes spectral classification, supergiants are class Ia or Ib . They typically have bolometric absolute magnitudes between -5 and -12...
of spectral and luminosity type O9.7 Ibe, with an absolute magnitude of -5.25 and an apparent magnitude of 2.0) and Alnitak Ab (a blue dwarf of spectral and luminosity type O V, with an absolute magnitude of about -3.0 and an apparent magnitude of about 4, discovered in 1998 ). Aa is estimated as being up to 28 times as massive as the sun, and to have a diameter 20 times greater. It is the brightest star of class O in the night sky. Alnitak B is a 4th magnitude B-type star which orbits Alnitak A every 1500 years. 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
IC 434
IC 434 is a bright emission nebula in the constellation Orion. It was discovered on February 1, 1786 by William Herschel.-External links:* * * SIMBAD Data:...
.
Etymology and cultural significance
The traditional name Alnitak, alternately spelled Al Nitak or Alnitah, is taken from the ArabicArabic language
Arabic is a name applied to the descendants of the Classical Arabic language of the 6th century AD, used most prominently in the Quran, the Islamic Holy Book...
النطاق an-nitaq, "the girdle".
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 H•akk 'the Accurate Scale Beam'. In Chinese mythologyChinese mythology
Chinese mythology is a collection of cultural history, folktales, and religions that have been passed down in oral or written tradition. These include creation myths and legends and myths concerning the founding of Chinese culture and the Chinese state...
they were known as The Weighing Beam.
The belt was also the Three Stars
Three Stars (Chinese constellation)
The Three Stars mansion is one of the twenty-eight mansions of the Chinese constellations. It is one of the western mansions of the White Tiger. This collection of seven bright stars is visible during winter in the Northern Hemisphere .- Asterisms :...
mansion , one of the Twenty-eight mansions
Twenty-eight mansions
The Twenty-eight Mansions , ', ' or ' are part of the Chinese constellations system. They can be considered as the equivalent to the zodiacal constellations in the Western astronomy, though the Twenty-eight Mansions reflect the movement of the Moon in a lunar month rather than the Sun in a solar year...
of the Chinese constellation
Chinese constellation
Chinese constellations are the way the ancient Chinese grouped the stars. They are very different from the modern IAU recognized constellations. This is because the IAU was based on Greco-Roman astronomy instead of Chinese astronomy....
s. It is one of the western mansions of the White Tiger.
In pre-Christian Scandinavia
Scandinavia
Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...
, the belt was known as Frigg
Frigg
Frigg is a major goddess in Norse paganism, a subset of Germanic paganism. She is said to be the wife of Odin, and is the "foremost among the goddesses" and the queen of Asgard. Frigg appears primarily in Norse mythological stories as a wife and a mother. She is also described as having the power...
's Distaff
Distaff
As a noun, a distaff is a tool used in spinning. It is designed to hold the unspun fibers, keeping them untangled and thus easing the spinning process. It is most commonly used to hold flax, and sometimes wool, but can be used for any type of fiber. Fiber is wrapped around the distaff, and tied in...
(Friggerock) or Freyja's distaff. Similarly Jacob's Staff and Peter's Staff were European biblical
Bible
The Bible refers to any one of the collections of the primary religious texts of Judaism and Christianity. There is no common version of the Bible, as the individual books , their contents and their order vary among denominations...
derived terms, as were the Three Magi, or the Three Kings. Väinämöinen
Väinämöinen
Väinämöinen is the central character in the Finnish folklore and the main character in the national epic Kalevala. His name comes from the Finnish word väinämö, meaning minstrel. Originally a Finnish god, he was described as an old and wise man, and he possessed a potent, magical...
's Scythe (Kalevala
Kalevala
The Kalevala is a 19th century work of epic poetry compiled by Elias Lönnrot from Finnish and Karelian oral folklore and mythology.It is regarded as the national epic of Finland and is one of the most significant works of Finnish literature...
) and Kalevan Sword are terms from Finnish mythology
Finnish mythology
Finnish mythology is the mythology that went with Finnish paganism which was practised by the Finnish people prior to Christianisation. It has many features shared with fellow Finnic Estonian mythology and its non-Finnic neighbours, the Balts and the Scandinavians...
.
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
Tiburón Island
Tiburón Island is both the largest island in the Gulf of California and the largest island in Mexico, with an area of . It was made a nature reserve in 1963 by President Adolfo López Mateos. Tiburón is Spanish for shark. The etymology of the Seri name is unknown...
.
In Latin America, this asterism is known as Las Tres Marías or As Três Marias which stand for The Three Marys in Spanish and Portuguese respectively.
In Christian astromythology Mintaka is also regarded as the third of the three Magi on their way to Bethlehem
Bethlehem
Bethlehem is a Palestinian city in the central West Bank of the Jordan River, near Israel and approximately south of Jerusalem, with a population of about 30,000 people. It is the capital of the Bethlehem Governorate of the Palestinian National Authority and a hub of Palestinian culture and tourism...
(Sirius
Sirius
Sirius is the brightest star in the night sky. With a visual apparent magnitude of −1.46, it is almost twice as bright as Canopus, the next brightest star. The name "Sirius" is derived from the Ancient Greek: Seirios . The star has the Bayer designation Alpha Canis Majoris...
): Caspar, Melchior
Melchior
Melchior is the name given in later legend to one of the Magi appearing in the Gospel of Matthew. It may also refer to:-First name:* Melchior Anderegg , Swiss mountain guide.* Melchior Berri , Swiss architect.* Melchior Broederlam Melchior is the name given in later legend to one of the Magi...
, Balthasar.
Namesakes
USS Alnitah (AK-127)USS Alnitah (AK-127)
The USS Alnitah was a Crater-class cargo ship in the service of the United States Navy in World War II. Named a spelling variation of the star Alnitak in the constellation Orion, it was the only ship of the Navy to bear this name....
was a United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
Crater class cargo ship
Crater class cargo ship
Crater-class cargo ship is a category of freighter that was constructed for use by the United States Navy during World War II under Maritime Commission EC2-S-C1 type....
named after the star.
See also
- Zeta Orionis in fiction
- Flame NebulaFlame NebulaThe Flame Nebula, designated as NGC 2024 and Sh2-277, is an emission nebula in the constellation Orion. It is about 900 to 1,500 light-years away....
External links
- Image of Alnitak from APODAstronomy Picture of the DayAstronomy Picture of the Day is a website provided by NASA and Michigan Technological University . According to the website, "Each day a different image or photograph of our universe is featured, along with a brief explanation written by a professional astronomer."The photograph is not necessarily...