Pi³ Orionis (π³ Orionis, abbreviated Pi³ Ori, π³ Ori), also named Tabit , is a

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

in the equatorial

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

Orion Orion may refer to: Common meanings * Orion (constellation), named after the mythical hunter * Orion (mythology), a hunter in Greek mythology Arts and media Fictional entities Characters and species * Orion (character), a DC Comics c ...

. At an

apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction of the object's light ca ...

of 3.16, it is readily visible to the naked eye and is the brightest star in the lion's hide (or shield) that Orion is holding. As measured using the

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different sightline, lines of sight and is measured by the angle or half-angle of inclination between those two lines. Due to perspective (graphica ...

technique, it is distant from the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

Nomenclature

''π³ Orionis'' ( Latinised to ''Pi³ Orionis'') is the system's

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

. It bore the traditional name of 'Tabit', from the

Arabic Arabic (, , or , ) is a Central Semitic languages, Central Semitic language of the Afroasiatic languages, Afroasiatic language family spoken primarily in the Arab world. The International Organization for Standardization (ISO) assigns lang ...

الثابت ''al-thābit'' 'the endurer (the fixed/constant one)'. In 2016, the IAU 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 approved the name ''Tabit'' for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names. In

Chinese Chinese may refer to: * Something related to China * Chinese people, people identified with China, through nationality, citizenship, and/or ethnicity **Han Chinese, East Asian ethnic group native to China. **'' Zhonghua minzu'', the supra-ethnic ...

, (), meaning '' Banner of Three Stars'', refers to an asterism consisting of π³ Orionis, ο¹ Orionis, ο² Orionis,

6 Orionis This is the list of notable stars in the constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythologi ...

, π¹ Orionis, π² Orionis, π⁴ Orionis, π⁵ Orionis and π⁶ Orionis. Consequently, the

Chinese name Chinese may refer to: * Something related to China * Chinese people, people identified with China, through nationality, citizenship, and/or ethnicity **Han Chinese, East Asian ethnic group native to China. **'' Zhonghua minzu'', the supra-ethni ...

for Pi³ Orionis itself is (), "the Sixth Star of Banner of Three Stars". According to ''Richard Hinckley Allen: Star Names – Their Lore and Meaning'', this star, together with ο¹ Orionis, ο² Orionis, π¹ Orionis, π² Orionis, π⁴ Orionis, π⁵ Orionis, π⁶ Orionis and 6 Orionis (are all of the 4th to the 5th magnitudes and in a vertical line), indicate the lion's skinwere but Al Tizini said that they were the Persians' ''Al Tāj'', "the Crown", or "Tiara", of their kings; and the Arabians' ''Al Kumm'', "the Sleeve", of the garment in which they dressed the Giant, the skin being omitted.

Ulugh Beg Mīrzā Muhammad Tarāghāy bin Shāhrukh (; ), better known as Ulugh Beg (; 22 March 1394 – 27 October 1449), was a Timurid sultan, as well as an astronomer and mathematician. Ulugh Beg was notable for his work in astronomy-related ma ...

called them ''Al Dhawāib'', "Anything Pendent"; and the

Borgia The House of Borgia ( ; ; Spanish and ; ) was a Spanish noble family, which rose to prominence during the Italian Renaissance. They were from Xàtiva, Kingdom of Valencia, the surname being a toponymic from the town of Borja, then in the Cro ...

n globe had the same, perhaps originated it.

Al Sufi ʿAbd al-Raḥmān al-Ṣūfī (; 7 December 90325 May 986) was a Persian astronomer. His work '' '' ("''The Book of Fixed Stars''"), written in 964, included both textual descriptions and illustrations. The Persian polymath Al-Biruni wrote tha ...

's title was ''Manica'', a Latin term for a protecting Gauntlet; and

Grotius Hugo Grotius ( ; 10 April 1583 – 28 August 1645), also known as Hugo de Groot () or Huig de Groot (), was a Dutch humanist, diplomat, lawyer, theologian, jurist, statesman, poet and playwright. A teenage prodigy, he was born in Delft an ...

gave a lengthy dissertation on the ''Mantile'', which some anonymous person applied to them, figured as a cloth thrown over the Giant's arm.

Properties

Pi³ Orionis is most likely single; a nearby star is probably an optical companion. It is a

main-sequence star In astronomy, the main sequence is a classification of stars which appear on plots of stellar color versus brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or dwarf stars, and positions of star ...

spectral type In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

F6 V. Since 1943, the

spectrum A spectrum (: spectra or spectrums) is a set of related ideas, objects, or properties whose features overlap such that they blend to form a continuum. The word ''spectrum'' was first used scientifically in optics to describe the rainbow of co ...

of this star has served as one of the stable anchor points by which other stars are classified. Compared to the Sun, it has about 129% of the

mass Mass is an Intrinsic and extrinsic properties, intrinsic property of a physical body, body. It was traditionally believed to be related to the physical quantity, quantity of matter in a body, until the discovery of the atom and particle physi ...

, 132% of the

radius In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...

, and nearly 3 times the

luminosity Luminosity is an absolute measure of radiated electromagnetic radiation, electromagnetic energy per unit time, and is synonymous with the radiant power emitted by a light-emitting object. In astronomy, luminosity is the total amount of electroma ...

. This energy is being radiated from the star's outer atmosphere at an

effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ...

of , giving it the yellow-white glow of an

F-type star In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

. Although a periodicity of 73.26 days has been observed in the star's radial velocity, it seems likely to be bound more to stellar activity than to a planetary object in close

orbit In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...

. No

substellar companion A substellar object, sometimes called a substar, is an astronomical object, the mass of which is smaller than the smallest mass at which hydrogen fusion can be sustained (approximately 0.08 solar masses). This definition includes brown dwarfs and f ...

has been detected so far around Tabit and the

McDonald Observatory McDonald Observatory is an astronomical observatory located near unincorporated community of Fort Davis in Jeff Davis County, Texas, United States. The facility is located on Mount Locke in the Davis Mountains of West Texas, with additional faci ...

team has set limits to the presence of one or more planets with masses between 0.84 and 46.7

Jupiter mass The Jupiter mass, also called Jovian mass, is the unit of mass equal to the total mass of the planet Jupiter. This value may refer to the mass of the planet alone, or the mass of the entire Jovian system to include the moons of Jupiter. Jupiter ...

es and average separations spanning between 0.05 and 5.2

astronomical unit The astronomical unit (symbol: au or AU) is a unit of length defined to be exactly equal to . Historically, the astronomical unit was conceived as the average Earth-Sun distance (the average of Earth's aphelion and perihelion), before its m ...

s. Thus, so far it appears that planets could easily orbit in the

habitable zone In astronomy and astrobiology, the habitable zone (HZ), or more precisely the circumstellar habitable zone (CHZ), is the range of orbits around a star within which a planetary surface can support liquid water given sufficient atmospheric pressu ...

without any complications caused by a gravitationally perturbing body.

References

External links

* {{DEFAULTSORT:Pi3 Orionis Orion (constellation)

Tabit Pi3 Orionis (π3 Orionis, abbreviated Pi3 Ori, π3 Ori), also named Tabit , is a star in the celestial equator, equatorial constellation of Orion (constellation), Orion. At an apparent visual magnitude of 3.16, it is Bortle Dark-Sky Sc ...

Orionis, Pi3 Orionis, 01 F-type main-sequence stars Suspected variables 033449 0178

1543 Year 1543 ( MDXLIII) was a common year starting on Monday of the Julian calendar. It is one of the years sometimes referred to as an " Annus mirabilis" because of its significant publications in science, considered the start of the Scientific ...

030652 BD+05 0762

Nomenclature

Properties

See also

References

External links