Tau Ceti e

Tau Ceti e, also called 52 Ceti e, is an exoplanet candidate orbiting Tau Ceti, first detected in 2012 by statistical analyses of the star's variations in radial velocity obtained using HIRES, AAPS and HARPS. Its possible properties were refined in 2017, where it was one of two planets recovered from new data, the other being Tau Ceti f. It would orbit at a distance of 0.552 AU (between the orbits of Venus and Mercury in the Solar System) with an orbital period of 168 days and has a minimum mass of 3.93 Earth masses. If Tau Ceti e possesses an Earth-like atmosphere, the surface temperature would be around 68 °C (341 K; 154 °F). Based upon the incident flux upon the planet, a study of planetary habitability by Güdel et al. (2014) suggested that the planet lies outside of the conservative habitable zone defined by the runaway greenhouse limit, but within the optimistic habitable zone defined by the "recent Venus" limit.

A 2021 study was unable to confirm this planet.