Tau Orionis (τ Ori, τ Orionis) is a solitary star in the constellation Orion. If an imaginary line is drawn north-west between the stars

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 ...

and

Mintaka Mintaka , designation Delta Orionis (δ Orionis, abbreviated Delta Ori, δ Ori) and 34 Orionis (34 Ori), is a multiple star system some 1,200 light-years from the Sun in the constellation of Orion. Together with Alnitak (Zeta Or ...

, Tau Orionis can be found roughly one-sixth of the way to Mintaka. It is visible to the naked eye with an

apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...

of 3.58. Based upon an annual parallax shift of 6.6 mas, it is located around 490 light years from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

. This is a B-type

giant star A giant star is a star with substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature.Giant star, entry in ''Astronomy Encyclopedia'', ed. Patrick Moore, New York: Oxford University Press ...

with a stellar classification of B5III5 III. It has around 5.4 times the

radius of the Sun Solar radius is a unit of distance used to express the size of stars in astronomy relative to the Sun. The solar radius is usually defined as the radius to the layer in the Sun's photosphere where the optical depth equals 2/3: :1\,R_ = 6.957\t ...

and 6.2 times the

Sun's mass The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass of ...

. The star shines with 933 times the

solar luminosity The solar luminosity (), is a unit of radiant flux ( power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun. One nominal ...

from its outer atmosphere at an effective temperature of 10,829 K. it is around 63 million years old, with a

peculiar velocity Peculiar motion or peculiar velocity refers to the velocity of an object relative to a ''rest frame'' — usually a frame in which the average velocity of some objects is zero. Galactic astronomy In galactic astronomy, peculiar motion refers to ...

through space of 16.9 km/s. Tau Orionis has three visual companions: magnitude 11.0 component B at an angular separation of 33.30″ along a position angle of 251°; magnitude 10.9 component C lying some 3.80″ from component B; and magnitude 10.9 component D at 36.0″ from τ Ori along a position angle of 51°, all as of 2011.

Proper names

According to Richard H. Allen, this star, along with β Eri, λ Eri and ψ Eri were Al Kursiyy al Jauzah, "the Chair (or "Footstool") of the Central One". However, per the catalogue of stars in the ''Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars'', ''Al Kursiyy al Jauzah'' were the title for just three stars: β Eri as ''Cursa'', ψ Eri as ''Al Kursiyy al Jauzah I'' and λ Eri as ''Al Kursiyy al Jauzah II'', excluding this star. In

Chinese Chinese can refer to: * Something related to China * Chinese people, people of Chinese nationality, citizenship, and/or ethnicity **''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation ** List of ethnic groups in China, people of ...

, (), meaning '' Jade Well'', refers to an asterism consisting of τ Orionis, β Eridani, λ Eridani and ψ Eridani. 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 τ Orionis itself is (, en, the Fourth Star of Jade Well.).AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 15 日
/ref> From this Chinese title, the name Yuh Tsing is derived.

References

External links

* {{DEFAULTSORT:Tau Orionis Suspected variables B-type giants Orion (constellation) Orionis, Tau Durchmusterung objects Orionis, 20 024674 034503

1735 Events January–March * January 2 – Alexander Pope's poem '' Epistle to Dr Arbuthnot'' is published in London. * January 8 – George Frideric Handel's opera ''Ariodante'' is premièred at the Royal Opera House in Covent ...