Epsilon Eridani

Star	listing of all stars

Epsilon Eridani is a main-sequence K-2 class star in the constellation of Eridanus (the river). It is the third closest star visible without a telescope, at 3.3 pc or 10.67 light years distance from Earth. It is also known as HD 22049, HR 1084, BD-09°697, GCTP 742.00 and LHS 1557.

Its closest neighbour is the UV Ceti Star System (UV and BL Ceti), 1.60 pc or 5.22 ly away.

It has 85% of the Sun's mass, almost that much of its diameter, and 28% of its luminosity.

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

In 1988, 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 second 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 appears frequently in science fiction.

• In the fictional Star Trek universe, it is considered by some fans to be the location of the planet Vulcan, the home of Mr. Spock. 40 Eridani is also commonly suggested. That Epsilon Eridani could be Vulcan's home star is contradicted by statements of Commander Tucker on Star Trek: Enterprise, where he states that Vulcan is 16 light years from Earth; 40 Eridani is given as the location by the authorized book Star Trek: Star Charts (Pocket Books, 2002).

• In the robot novels of Isaac Asimov, it is the sun of the first world of the second wave of settlers: Baleyworld (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.

• Gerry Anderson's television show Space Precinct is set on a planet in the "Epsilon Erandi" system, which may be an error for Epsilon Eridani.

See also

• List of nearest stars

it:Epsilon Eridani ja:エリダヌス座ε星 nl:Epsilon Eridani