Tau Ceti

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Tau Ceti (τ Cet, τ Ceti) is a star in the constellation Cetus that is similar to the Sun in mass and spectral type. At a distance of just under 12 light years from the Solar System, it is a relatively close star. Tau Ceti is metal-deficient and so is thought to be less likely to host rocky planets. Observations have detected more than 10 times as much dust surrounding Tau Ceti as is present in the Solar System. The star appears stable, with little stellar variation.

Astrometric or radial velocity measurements have not yet detected companions around Tau Ceti, but given current search refinement, this only excludes substellar companions such as large brown dwarfs. Because of its debris disk, any planet orbiting Tau Ceti would face far more impact events than the Earth. Despite this hurdle to habitability, its solar analog (Sun-like) characteristics have led to widespread interest in the star. Given its stability and similarity to the Sun, Tau Ceti is consistently listed as a target for the Search for Extra-Terrestrial Intelligence (SETI), and it appears in some science fiction literature.

Unlike other prominent stars, Tau Ceti does not have a widely recognized traditional name.[nb 1] It can be seen with the unaided eye as a faint third-magnitude star.[nb 2] As seen from Tau Ceti, the Sun would be a third-magnitude star in the constellation Boötes.[nb 3]



The proper motion of a star is its amount of movement across the celestial sphere, determined by comparing its position relative to more distant background objects. Tau Ceti is considered to be a high-proper-motion star, although it only has an annual traverse of just under two arc seconds.[nb 4] It will require about two thousand years before the location of this star shifts by more than a degree. A high proper motion is an indicator of closeness to the Sun.[11] Nearby stars can traverse an angle of arc across the sky more rapidly than the distant background stars and are good candidates for parallax studies. In the case of Tau Ceti, the parallax measurements indicate a distance of 11.9 light-years. This makes it one of the closest star systems to the Sun, and the next-closest spectral class-G star after Alpha Centauri A.[12]

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