81 Ceti b

{{Short description|Extrasolar planet in the constellation Cetus}}

{{Infobox planet

| name = 81 Ceti b

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| discoverer = Sato et al.

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| discovered = July 2, 2008

| discovery_method = Doppler Spectroscopy

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| apsis = astron

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| semimajor = {{convert|2.5|AU|km|abbr=on}}

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| eccentricity = 0.206 ± 0.029

| period = 952.7 ± 8.8 d

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| time_periastron = 2486 ± 26

| arg_peri = 175 ± 69

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| star = 81 Ceti

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| mean_radius = 1.14 {{Jupiter radius|link=y}} Estimate

| mass = 5.30 {{Jupiter mass|link=y}}[https://exoplanets.nasa.gov/exoplanet-catalog/7012/81-ceti-b/ NASA 7012][https://exoplanet.eu/catalog/81_cet_b--490/ 81 Ceti b]

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81 Ceti b (abbreviated 81 Cet b) is an extrasolar planet approximately 331 light years away in the constellation of Cetus. It is estimated to be 5.3 times the mass of Jupiter which also makes it a gas giant. It orbits the K-type giant star 81 Ceti at an average distance of 2.5 AU, taking about 2.6 years to revolve with an eccentricity of 0.206.