, the planets' orbits could be similarly inclined. If the debris disk and f's orbits were assumed to be equal, f would be between and Earth masses, making it slightly more likely to be a mini-Neptune. Tau Ceti e Tau Ceti e is a confirmed planet orbiting Tau Ceti that was detected by statistical analyses of the data of the star's variations in radial velocity that were obtained using HIRES, AAPS, and HARPS. Its possible properties were refined in 2017: it orbits 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 possessed an Earth-like atmosphere, the surface temperature would be around . Based upon the incident flux upon the planet, a study by Güdel et al. (2014) speculated that the planet may lie outside the habitable zone and closer to a Venus-like world. Tau Ceti f Tau Ceti f is a confirmed super-Earth orbiting Tau Ceti that was discovered in 2012 by statistical analyses of the star's variations in radial velocity, based on data obtained using HIRES, AAPS, and HARPS. It is of interest because its orbit places it in Tau Ceti's extended habitable zone. However, a 2015 study implies that it has been in the temperate zone for less than one billion years, so there may not be a detectable biosignature. Few properties of the planet are known other than its orbit and mass. It orbits Tau Ceti at a distance of 1.35 AU (near Mars's orbit in the Solar System) with an orbital period of 642 days and has a minimum mass of 3.93 Earth masses. Debris disk In 2004, a team of UK astronomers led by Jane Greaves discovered that Tau Ceti has more than ten times the amount of cometary and asteroidal material orbiting it than does the Sun. This was determined by measuring the disk of cold dust orbiting the star produced by collisions between such small bodies. This result puts a damper on the possibility of complex life in the system, because any planets would suffer from large impact events roughly ten times more frequently than Earth. Greaves noted at the time of her research that "it is likely that [any planets] will experience constant bombardment from asteroids of the kind believed to have wiped out