Epsilon Tauri or ε Tauri, formally named Ain (), is an

orange giant 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, ...

star A star is an astronomical object comprising a luminous spheroid of plasma held together by its gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night, but their immense distances from Earth make ...

located approximately 45

parsec The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, a ...

s (147

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 101 ...

s) 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 rad ...

in the constellation of Taurus. An

extrasolar planet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

(designated

Epsilon Tauri b Epsilon Tauri b (abbreviated ε Tauri b or ε Tau b), formally named Amateru , is a super-Jupiter exoplanet orbiting the K-type giant star Epsilon Tauri approximately 155 light-years (47.53 parsecs, or nearly km) away from the Earth in the c ...

, later named Amateru) is believed to be orbiting the star. It is a member of the Hyades

open cluster An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and ...

. As such its age is well constrained at 625 million years. It is claimed to be the heaviest among planet-harboring stars with reliable initial masses although the star HD 13189 is potentially more massive. Given its large mass, this star, though presently of

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 th ...

K0 III, was formerly of spectral type A that has now evolved off the

main sequence In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Her ...

into the giant phase. It is regarded as a red clump giant; that is, a core-helium burning star. Since Epsilon Tauri lies near the plane of the

ecliptic The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic agai ...

, it is sometimes occulted by the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width ...

and (very rarely) by

planet A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a ...

s. It has an 11th magnitude companion 182

arcsecond 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 na ...

s from the primary.

Nomenclature

''ε Tauri'' ( Latinised to ''Epsilon Tauri'') 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. T ...

; it also bears the

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 c ...

of 74 Tauri. On discovery, the planet was designated Epsilon Tauri b (or Ain b). The star bore the traditional name ''Ain'' (

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; Walte ...

''عين'' for "eye") and was given the name ''Oculus Boreus'' (

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...

for "Northern eye") by

John Flamsteed John Flamsteed (19 August 1646 – 31 December 1719) was an English astronomer and the first Astronomer Royal. His main achievements were the preparation of a 3,000-star catalogue, ''Catalogus Britannicus'', and a star atlas called '' Atlas C ...

. 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, outreach ...

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 List of proper names of stars, proper names for stars for the international astronomical community. It operates under ...

(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 ''Ain'' for this star. In July 2014, the

launched

NameExoWorlds NameExoWorlds (also known as IAU NameExoWorlds) is the name of various projects managed by the International Astronomical Union (I.A.U.) to encourage names to be submitted for astronomical objects, which would later be considered for official ad ...

, a process for giving proper names to certain exoplanets. The process involved public nomination and voting for the new names. In December 2015, the IAU announced the winning name was ''Amateru'' for this planet. The winning name was based on that submitted by the Kamagari Astronomical Observatory of

Kure is a port and major shipbuilding city situated on the Seto Inland Sea in Hiroshima Prefecture, Japan. With a strong industrial and naval heritage, Kure hosts the second-oldest naval dockyard in Japan and remains an important base for the Japan ...

Hiroshima Prefecture is a prefecture of Japan located in the Chūgoku region of Honshu. Hiroshima Prefecture has a population of 2,811,410 (1 June 2019) and has a geographic area of 8,479 km² (3,274 sq mi). Hiroshima Prefecture borders Okayama Prefecture to the ...

, Japan: namely ' Amaterasu', the Shinto goddess of the Sun, born from the left eye of the god

Izanagi Izanagi (イザナギ/伊邪那岐/伊弉諾) or Izanaki (イザナキ), formally known as , is the creator deity (''kami'') of both creation and life in Japanese mythology. He and his sister-wife Izanami are the last of the seven generations of ...

. The IAU substituted 'Amateru' – which is a common Japanese appellation for

shrine A shrine ( la, scrinium "case or chest for books or papers"; Old French: ''escrin'' "box or case") is a sacred or holy space dedicated to a specific deity, ancestor, hero, martyr, saint, daemon, or similar figure of respect, wherein they ...

s when they enshrine Amaterasu – because 'Amaterasu' is already used for an asteroid (

10385 Amaterasu 1 (one, unit, unity) is a number representing a single or the only entity. 1 is also a numerical digit and represents a single unit of counting or measurement. For example, a line segment of ''unit length'' is a line segment of length 1. ...

). In Chinese, (), meaning '' Net'', refers to an asterism consisting ε Tauri, δ³ Tauri, δ¹ Tauri, γ Tauri,

Aldebaran Aldebaran (Arabic: “The Follower”, "الدبران") is the brightest star in the zodiac constellation of Taurus. It has the Bayer designation α Tauri, which is Latinized to Alpha Tauri and abbreviated Alpha Tau or α Tau. Aldeb ...

, θ² Tauri, 71 Tauri and

λ Tauri Lambda Tauri (λ Tau, λ Tauri) is a triple star system in the constellation Taurus. In the ''Calendarium of Al Achsasi Al Mouakket'', this star was designated ''Sadr al Tauri'', which was translated into Latin as ''Pectus Tauri'', meani ...

. 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 oft ...

for ε Tauri itself is (), "the First Star of Net".香港太空館 – 研究資源 – 亮星中英對照表
, Hong Kong Space Museum. Accessed on line November 23, 2010.

Planetary system

In 2007, a massive

was reported orbiting the star with a period of 1.6 years in a somewhat eccentric orbit. Its discoverers claimed it was the first planet ever discovered in an open cluster.

References

External links

* * {{DEFAULTSORT:Epsilon Tauri K-type giants Horizontal-branch stars Planetary systems with one confirmed planet Hyades (star cluster) Taurus (constellation) Ain Tauri, Epsilon Durchmusterung objects Tauri, 074 028305 020889 1409 TIC objects

Nomenclature

Planetary system

See also

References

External links