Epsilon Eridani
Encyclopedia : E : EP : EPS : Epsilon Eridani
|- style="vertical-align: top;" | B-V color index | |- style="vertical-align: top;" | U-B color index | |- style="vertical-align: top;" | Variable type |
|- ! style="background-color: #FFFFC0;" colspan="2" | Details |- |style="vertical-align: baseline;" | Mass | M☉ |- |style="vertical-align: baseline;" | Radius | R☉ |- |style="vertical-align: baseline;" | Luminosity | L☉ |- |style="vertical-align: baseline;" | Temperature | K |- |style="vertical-align: baseline;" | Metallicity | |- |style="vertical-align: baseline;" | Rotation | |- |style="vertical-align: baseline;" | Age | })<()or(}})=()and(}})<())}}} years
|- ! style="background-color: #FFFFC0;" colspan="2" | Other designations |- | colspan="2" |
|}Epsilon Eridani (ε Eri / ε Eridani) is a main-sequence K2 class star in the constellation of Eridanus. It is the third closest star outside of the solar system visible without a telescope. 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. A planet orbiting Epsilon Eridani at a distance of around 0.53 astronomical units would have temperatures suitable for liquid water.
Its closest neighbour is Luyten 726-8 (UV Ceti and BL Ceti), 5.22 ly (1.60 pc) away.
Dust disc
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. The dust disc contains approximately 1000 times more dust than is present in the inner system around our Sun, which may mean it has about 1000 times as much cometary material as our solar system.
Within 35 AU of the star the dust is depleted, which may mean that the system has formed planets which have cleared out the dust in this region. This is consistent with currently accepted models of the inner solar system, and so there may be terrestrial planets around the star.
Planetary system
As Epsilon Eridani is one of the nearest solar-type stars to our Sun, many attempts to search for orbiting planets have been made. However, the star's high activity and variability means that finding planets with the radial velocity method is difficult, and stellar activity may mimic the presence of planets.
Epsilon Eridani b
Epsilon Eridani b is a extrasolar planet candidate around Epsilon Eridani, announced in 2000 by a team led by Artie Hatzes. The discoverers gave its mass as 1.2 ± 0.33 times that of Jupiter, with a mean distance of 3.3 AU from the star. The object's orbit is highly eccentric. Other observers, including Geoffrey Marcy required more information on the star's doppler noise behaviour created by its large and varying magnetic field, and the discovery remains controversial. Its existence had also been previously suspected by a Canadian team led by Bruce Campbell and Gordon Walker in the early 1990s, but their observations weren't definitive enough to make a solid discovery.
Epsilon Eridani c
A hypothetical planet designated Epsilon Eridani c was proposed in 2002 based on analysis of the structure of the dust disk around the star. Clumping in the dust disk can be modelled by dust particles being trapped in resonances with a planet in an eccentric orbit. As of 2006 the existence of this planet has not been confirmed.
Epsilon Eridani in 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 , 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 series Babylon 5, the space station itself orbits the third planet (Epsilon 3) in this system.
- In the Viagens Interplanetarias stories of L. Sprague de Camp its system contains the inhabited planets of Thor and Kukulcan, the later being the setting of his novels The Stones of Nomuru and The Venom Trees of Sunga.
- In the Battletech universe Epsilon Eridani is one of the worlds closest to Terra. It was originally a member-world of the Terran Hegemony. The planet passed into Capellan control after the collapse of the Star League. It was conquered by the Federated Suns during the 4th Succession War, and remained under the control of the Federated Suns, later the Federated Commonwealth, until 3057, when the world became independent in the aftermath of the conflict between the Federated Commonwealth and an alliance between the Capellan Confederation and the Free Worlds League.
- 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, a shipyard, and the site of the SPARTAN project which produced Master Chief. The planet was destroyed August 30, 2552.
- 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.
- In the game Face of Mankind there's a space colony on one of the ice planets orbiting Epsilon Eridani.
- In the Honor Harrington book series by David Weber, Epsilon Eridani is one of the Solarian League worlds, and the source of the Eridani Edict, which sprung from the Epsilon Eridani Massacre where 7 billion people were killed by orbital bombardment.
See also
References
External links
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
From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.