Epsilon Eridani is a main-sequence star in the constellation of Eridanus (the river). It is the third closest star visible without a telescope.

It has 85% of the Sun's mass, almost that much of its diameter, and 28% of its luminosity. It is 10.5 light years from Earth.

Its spectrum is extremely variable, with many emission liness. It has a very strong magnetic field. It spins about every 11 days. The reason for all this is the fact that it is very young; only about half a billion years old. It is for this reason why it is now considered unlikely to have intelligent life in its system. Tau Ceti is a much better candidate. Both stars appear deficient in iron.

In 1998, a dust disk was discovered around the star. It is about the distance the Kuiper belt is from our sun. There are clumps in the dust ring which may suggest that another planet orbits the star, causing the clumps through resonance. In 2000 a Jupiter-like planet was discovered (or confirmed) as being in orbit around the star. Its mean distance is 3.3 AU and its mass is estimated by the astronomer George Gatewood as 1.2 times the mass of Jupiter. Its orbit is highly elliptical. There may also be a third planet with about 3-5 times Jupiter's mass orbiting in an elliptical orbit every 25 years or so. Close to the star, there is no evidence of the dust ring. This is consistent with currently accepted models of the inner solar system, and so there may be terrestrial planets here. Then again, Epsilon Eridani is very heavy-element poor. A planet orbiting Epsilon Eridani at a distance of around 0.53 astronomical units would have temperatures suitable for liquid water.

Epsilon Eridani in Science Fiction

Because of its status as the closest, single sun-like star, Epsilon Eridani is frequently chosen by science fiction authors to figure in their output.

  • In the fictional Star Trek universe, it is the sun of the planet Vulcan, the home of Mr. Spock.

  • In the robot novels of Isaac Asimov, it is the sun of the first world of the 2nd wave of settlers: Baley's World (Robots and Empire) or Comporellon (Foundation's Edge).

  • In the television show "Babylon 5," the station itself lies in orbit around a planet in this system.

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