Epsilon Eridani

Epsilon Eridani (ε Eri / ε Eridani) is a main-sequence K2 class star in the constellation of Eridanus. It is the third closest star visible without a telescope.

Epsilon Eridani the star

Its closest neighbour is Luyten 726–8 (UV Ceti and BL Ceti), 5.22 ly (1.60 pc) 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.²

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, and like Epsilon Eridani, is also deficient in iron.

In 1988, a dust disk was discovered around the star, at a similar distance as the Kuiper belt is from our Sun. Bruce Campbell and others interpreted doppler measurements as clumps in the dust ring that suggest another planet orbits the star, causing the clumps through resonance.

In 2000 the astronomer George Gatewood reported a Jupiter-like planet Epsilon Eridani b as being in orbit around the star and gave its mass as 1.2 +/- 0.33 Jupiter masses, with a mean distance is 3.3 AU a highly elliptical orbit. However other observers (Marcy et al) required more information on the star's doppler noise behaviour created by its large and varying magnetic field.³

Close to the star, there is no evidence of the dust ring.^jac This is consistent with currently accepted models of the inner solar system, and so there may be terrestrial planets here. Epsilon Eridani is poor in metals. 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.

• In the video game series Halo, the planet Reach is in this system. Reach is a military stronghold, and the site of the SPARTAN project which produced Master Chief. Also, Eridani II is the birthplace of Master Chief.

• In the hard science fiction novels by author Alastair Reynolds, the Chasm City habitat and Glitter Band are located on and around the planet Yellowstone in this system.

• In the Worldwar books by Harry Turtledove, Epsilon Eridani is one of the subject star systems ("Rabotev") of the alien Race.

See also

• List of nearest stars

Reference

• Note Baliunas: Sallie Baliunas, Dmitry Sokoloff, and Willie Soon (1996 February 1). "Magnetic Field and Rotation in Lower Main-Sequence Stars: An Empirical Time-Dependent Magnetic Bode's Relation?". THE ASTROPHYSICAL JOURNAL 457 (Number 2, Part 2): L99–L102.
  • "Magnetic Field and Rotation in Lower Main-Sequence Stars." THE ASTROPHYSICAL JOURNAL. Accessed on March 10, 2005. (colour index, magnetic heating, and rotational period for 112 stars)
• Note schneider: "Notes for Epsilon Eridani." Extra-solar Planets Catalog. Accessed on March 24, 2005.
• Note jac: "Astronomers discover a nearby star system just like our own Solar System." JAC/UCLA. Accessed on March 24, 2005.

External links

Epsilon Eridani

Notes

• Note 1: ^Baliunas this makes it redder than the Sun with B-V of 0.65
• Note 2: ^Baliunas measured a rotation period of 12 days
• Note 3: ^schneider