Epsilon Tauri b (abbreviated ε Tauri b or ε Tau b), formally named Amateru , is a super-Jupiter

exoplanet 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 ...

orbiting the K-type giant star

Epsilon Tauri Epsilon Tauri or ε Tauri, formally named Ain (), is an orange giant star located approximately 45 parsecs (147 light-years) from the Sun in the constellation of Taurus. An extrasolar planet (designated Epsilon Tauri b, later named Amate ...

approximately 155

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 1012 ...

s (47.53 parsecs, or nearly km) away from the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

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, mythological subject, or inanimate object. The origins of the e ...

Taurus Taurus is Latin for 'bull' and may refer to: * Taurus (astrology), the astrological sign * Taurus (constellation), one of the constellations of the zodiac * Taurus (mythology), one of two Greek mythological characters named Taurus * ''Bos taurus ...

. It orbits the star further out than Earth orbits the Sun. It has moderate eccentricity.

Name

In July 2014, 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 ...

(IAU) launched NameExoWorlds, 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 name was based on that submitted by the Kamagari Astronomical Observatory of Kure,

Hiroshima Prefecture is a Prefectures of Japan, 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 ...

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

: namely '

Amaterasu Amaterasu, also known as Amaterasu Ōmikami () or Ōhirume no Muchi no Kami (), is the goddess of the sun in Japanese mythology. One of the major deities (''kami'') of Shinto, she is also portrayed in Japan's earliest literary texts, the ''Kojik ...

', the

Shinto Shinto () is a religion from Japan. Classified as an East Asian religion by scholars of religion, its practitioners often regard it as Japan's indigenous religion and as a nature religion. Scholars sometimes call its practitioners ''Shintois ...

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 are the deities, divinities, spirits, phenomena or "holy powers", that are venerated in the Shinto religion. They can b ...

. The IAU substituted 'Amateru' - which is a common Japanese

appellation An appellation is a legally defined and protected geographical indication primarily used to identify where the grapes for a wine were grown, although other types of food often have appellations as well. Restrictions other than geographical boun ...

for

shrines A shrine ( la, scrinium "case or chest for books or papers"; Old French: ''escrin'' "box or case") is a sacred or holy sacred space, space dedicated to a specific deity, ancestor worship, ancestor, hero, martyr, saint, Daemon (mythology), daem ...

when they enshrine Amaterasu - because 'Amaterasu' is already used for asteroid 10385 Amaterasu.

Characteristics

Mass, radius and temperature

Epsilon Tauri b is a " super-Jupiter", an exoplanet that has a radius and mass larger than that of the gas giants

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...

and

Saturn Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...

. It has a temperature of . It has an estimated mass of around 7.6 and a potential radius of around 18% larger than Jupiter (1.18 , or 12 ) based on its mass, since it is more massive than the jovian planet.

Host star

The planet orbits a ( K-type) giant star named

. It has exhausted the

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

supply in its core and is currently fusing helium. The star has a mass of 2.7 and a radius of around 12.6 . It has a surface temperature of 4901 K and is 625 million years old. In comparison, the Sun is about 4.6 billion years old and has a surface temperature of 5778 K. The star's

apparent 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 li ...

, or how bright it appears from Earth's perspective, is 3.53. Therefore, Epsilon Tauri can be seen with the naked eye.

Orbit

Epsilon Tauri b orbits its star with nearly 97 times the Sun's luminosity (97 ) every 645 days at a distance of 1.93 AU (compared to

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...

' orbital distance from the Sun, which is 1.52 AU). It has a mildly eccentric orbit, with an eccentricity of 0.15.

Discovery

Epsilon Tauri b was discovered by using the High Dispersion Echelon Spectrograph at Okayama Astrophysical Observatory (OAO) as part of a process to study G-type and K-type giant stars to search for exoplanets. Measurements of radial velocity from Epsilon Tauri were taken between December 2003 and July 2006. Wobbles in the star were detected, and after analyzing the data, it was eventually concluded that there was a planetary companion with a mass 7 times that of Jupiter orbiting Epsilon Tauri every 645 days, or nearly 2 years with an eccentricity of 0.15.

In popular culture

The planet Amateru is mentioned by name in the science fiction book Starsong Chronicles: Exodus by American author JJ Clayborn.

References

External links

* {{Sky, 04, 28, 37.0, +, 19, 10, 50 Taurus (constellation) Giant planets Exoplanets discovered in 2007 Exoplanets detected by radial velocity Exoplanets with proper names Hyades (star cluster)