Epsilon Tauri b
{{Short description|Super Jupiter orbiting Epsilon Tauri}}
{{Infobox planet
| name = Epsilon Tauri b / Amateru
| image = File:Planet_Epsilon_Tauri_b.png
| caption = Artistic simulation of Epsilon Tauri b orbiting its host star.
| discoverer = Sato et al.
| discovered = 7 February 2007
| discovery_method = Doppler spectroscopy
| apsis = astron
| semimajor = {{val|1.878|0.001|ul=AU}}
| eccentricity = {{val|0.076|0.009|0.008}}
| period = {{val|585.82|0.26|0.33|ul=d}}
| time_periastron = {{val|2453492.3|11.3|10.0|ul=JD}}
| arg_peri = {{val|107.90|6.82|6.07|u=deg}}
| semi-amplitude = {{val|93.24|0.74|0.73|ul=m/s}}
| star = Epsilon Tauri
| mean_radius =
| mass = {{val|7.190|0.056|p=≥|ul=Jupiter mass}}
| single_temperature =
}}
Epsilon Tauri b (abbreviated ε Tauri b or ε Tau b), formally named Amateru {{IPAc-en|æ|m|@|'|t|E|r|uː}}, is a super-Jupiter exoplanet orbiting the K-type giant star Epsilon Tauri approximately {{convert|146|ly|pc|lk=on|abbr=off}} away from the Earth in the constellation of Taurus.{{cite web|url=http://exoplanetarchive.ipac.caltech.edu/cgi-bin/DisplayOverview/nph-DisplayOverview?objname=Epsilon+Tauri+b|title=Epsilon Tauri b|work=NASA Exoplanet Archive|accessdate=28 July 2016}} It orbits the star further out than Earth orbits the Sun. It has moderate eccentricity.
The planet orbits one of the four giant stars in the Hyades star cluster, and was the first planet ever discovered in an open cluster.
Name
In July 2014, the International Astronomical Union (IAU) launched NameExoWorlds, a process for giving proper names to certain exoplanets.[http://www.iau.org/news/pressreleases/detail/iau1404/ NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars]. IAU.org. 9 July 2014 The process involved public nomination and voting for the new names.{{Cite web |url=http://nameexoworlds.iau.org/process |title=NameExoWorlds The Process |access-date=2015-09-05 |archive-date=2015-08-15 |archive-url=https://web.archive.org/web/20150815025117/http://www.nameexoworlds.iau.org/process |url-status=dead }} In December 2015, the IAU announced the winning name was Amateru for this planet.[http://www.iau.org/news/pressreleases/detail/iau1514/ Final Results of NameExoWorlds Public Vote Released], International Astronomical Union, 15 December 2015. The name was based on that submitted by the Kamagari Astronomical Observatory of Kure, Hiroshima Prefecture, Japan: namely 'Amaterasu', the Shinto goddess of the Sun, born from the left eye of the god Izanagi. The IAU substituted 'Amateru' - which is a common Japanese appellation for shrines when they enshrine Amaterasu - because 'Amaterasu' is already used for asteroid 10385 Amaterasu.{{Cite web |url=http://nameexoworlds.iau.org/names |title=NameExoWorlds The Approved Names |access-date=2015-12-21 |archive-date=2018-02-01 |archive-url=https://web.archive.org/web/20180201043609/http://nameexoworlds.iau.org/names |url-status=dead }}
Characteristics
=Mass, radius and temperature=
Epsilon Tauri b is a "super-Jupiter", an exoplanet that has a mass larger than that of the gas giants Jupiter and Saturn. It has a temperature of {{convert|541|K|C F}}.{{cn|date=March 2025}} It has a minimum mass of around {{Jupiter mass|7.2}} and a potential radius of around 18% larger than Jupiter (1.18 {{Jupiter radius}}, or 12 {{Earth radius}}) based on its mass, since it is more massive than the jovian planet.{{cn|date=March 2025}}
=Host star=
The planet orbits a (K-type) giant star named Epsilon Tauri. It has exhausted the hydrogen supply in its core and is currently fusing helium. The star has a mass of 2.7 {{Solar mass}} and a radius of around 12.6 {{Solar radius}}. 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{{cite web |url=http://www.universetoday.com/18237/how-old-is-the-sun/ |title=How Old is the Sun? |author=Fraser Cain |date=16 September 2008 |website= |publisher=Universe Today |accessdate=19 February 2011}} and has a surface temperature of 5778 K.{{cite web |url=http://www.universetoday.com/18092/temperature-of-the-sun/ |title=Temperature of the Sun |author=Fraser Cain |date=September 15, 2008 |website= |publisher=Universe Today |accessdate=19 February 2011}}
The star's apparent magnitude, or how bright it appears from Earth's perspective, is 3.53. Therefore, Epsilon Tauri can be seen with the naked eye.
= Orbit =
Discovery
Epsilon Tauri b was discovered by using the High Dispersion Echelle 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 595 days, or nearly 2 years with an eccentricity of 0.15. These values were later refined to a period of 586 days and an eccentricity of 0.08.
==In popular culture==
The planet Amateru is mentioned by name in the science fiction book Starsong Chronicles: Exodus by American author JJ Clayborn.
See also
References
{{Reflist|colwidth=30em|refs=
| title=Starsong Chronicles: Exodus
| last1=Clayborn | first1=JJ
| date=March 2017
| publisher=Independently Published | isbn=978-1520611747}}
{{cite journal |last1=Teng |first1=Huan-Yu |last2=Sato |first2=Bun'ei |display-authors=etal |date=August 2023 |title=Revisiting planetary systems in the Okayama Planet Search Program: A new long-period planet, RV astrometry joint analysis, and a multiplicity-metallicity trend around evolved stars |journal=Publications of the Astronomical Society of Japan |volume=75 |issue=6 |pages=1030–1071 |doi=10.1093/pasj/psad056 |arxiv=2308.05343 |bibcode=2023PASJ...75.1030T}}
}}
External links
- {{cite encyclopedia|url=https://exoplanet.eu/catalog/eps_tau_b--365/ |encyclopedia=Extrasolar Planets Encyclopaedia |title=Notes for planet eps Tau b |access-date=2008-06-24 }}
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{{Sky|04|28|37.0|+|19|10|50}}
Category:Taurus (constellation)
Category:Exoplanets discovered in 2007
Category:Exoplanets detected by radial velocity