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Encyclopedia > Epsilon Eridani
Epsilon Eridani
Observation data
Epoch J2000
Constellation Eridanus
Right ascension 3h 32m 55.8s
Declination -9° 27' 29.7"
Apparent magnitude (V) 3.73
Spectral Characteristics
Spectral type K2V
U-B color index 0.59
B-V color index 0.88
Variable type BY Draconis
Astrometry
Radial velocity (Rv) 15 km/s
Proper motion (μ) RA: -976.44 mas/yr
Dec.: 17.97 mas/yr
Parallax (π) 310.75 ± 0.85 mas
Distance 10.5 ± 0.03 ly
(3.218 ± 0.009 pc)
Absolute magnitude (MV) 6.192
Physical Characteristics
Mass 0.85 M
Radius 0.84 R
Luminosity 0.28 L
Temperature 5,100 K
Metallicity 49–65% Sun
Rotation 11.1 days
Age 5 × 108 years
Other designations
18 Eri, HD 22049, HR 1084, BD-09°697, GCTP 742.00, WDS 03330-0928, SAO 130564, LHS 1557

Epsilon Eridani (ε Eri / ε Eridani) is a notable main-sequence K2 class star in the constellation of Eridanus. It has no official proper name (called only by its Bayer designation), although Arab settlers along the East African coast occasionally applied the name الصادرة Al-Sadirah "the Returning Ostriches" to the star nearly seven centuries ago.[citation needed] In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... This article or section does not cite its references or sources. ... Eridanus is the sixth largest of the 88 modern constellations. ... Equatorial Coordinates Right ascension (abbrev. ... In astronomy, declination (dec) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. ... // Headline text HEY!! HOW ARE YOU ALL?? Its nice of you to come read this page. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics. ... In astronomy, the color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature. ... In astronomy, the color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature. ... Most stars are of almost constant luminosity. ... BY Draconis variables are main sequence variable stars of late spectral types, usually K or M. They exhibit variations in their luminosity due to rotation of the star coupled with star spots, and other chromospheric activity. ... This article does not cite its references or sources. ... Radial velocity is the velocity of an object in the direction of the line of sight. ... kilometre per second is an SI derived unit of both speed (scalar) and velocity (vector), signified by the symbol km/s or km s-1. ... The proper motion of a star is the motion of the position of the star in the sky (the change in direction in which we see it, as opposed to the radial velocity) after eliminating the improper motions of the stars, which affect their measured coordinates but are not real... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... This does not cite its references or sources. ... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... Distance is a numerical description of how far apart things lie. ... A light-year or lightyear, symbol ly, is a unit of length. ... Stellar parallax motion The parsec (symbol pc) is a unit of length used in astronomy. ... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standard luminosity distance away from us, in the absence of interstellar extinction. ... Unsolved problems in physics: What causes anything to have mass? Mass is a property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... In astronomy, the solar mass is a unit of mass used to express the mass of stars and larger objects such as galaxies. ... In classical geometry, a radius of a circle or sphere is any line segment from its center to its boundary. ... In astronomy, the solar radius is a unit of length used to express the size of stars and larger objects such as galaxies. ... Luminosity has different meanings in several different fields of science. ... The solar luminosity, , is a unit of luminosity (power emitted in the form of photons) conventionally used by astronomers to give the luminosities of stars. ... Fig. ... The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero—the lowest possible temperature where nothing could be colder and no heat energy remains in a substance—is defined as zero kelvin (0 K). ... In astronomy, the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium. ... A sphere rotating around its axis. ... The Pleiades, an open cluster of stars in the constellation of Taurus. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... In astronomy, many stars are referred to simply by catalogue numbers. ... Flamsteed designations for stars are similar to Bayer designations, except that they use numbers instead of Greek letters. ... The Henry Draper Catalogue is an astronomy catalogue with astrometric and spectroscopic data about more than 225,000 stars. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... Smithsonian Astrophysical Observatory Star Catalog contain the 258,996 stars. ... In astronomy, many stars are referred to simply by catalogue numbers. ... Hertzsprung-Russell diagram The main sequence of the Hertzsprung-Russell diagram is the curve where the majority of stars are located in this diagram. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics. ... The Pleiades, an open cluster of stars in the constellation of Taurus. ... This article or section does not cite its references or sources. ... Eridanus is the sixth largest of the 88 modern constellations. ... The Arabs (Arabic: عرب) are a heterogeneous ethnic group who are predominantly speakers of the Arabic language, mainly found throughout the Middle East and North Africa. ...  Eastern Africa (UN subregion)  East African Community  Central African Federation (defunct)  geographic, including above East Africa or Eastern Africa is the easternmost region of the African continent, variably defined by geography or geopolitics. ... Binomial name Struthio camelus Linnaeus, 1758 The present-day distribution of ostriches. ...


Epsilon Eridani is the third closest star outside of the solar system visible without a telescope. It has 85% of the Sun's mass, is roughly the same size, but has only 28% of its luminosity, and is 10.522 light years distant. This list of the nearest stars to Earth is ordered by increasing distance out to a maximum of 5 parsecs (16. ... 50 cm refracting telescope at Nice Observatory. ... For other uses, see Sun (disambiguation). ...


Epsilon Eridani's most unusual characteristic is its extremely variable spectrum, with many emission lines. Futhermore, it has a very strong magnetic field and has been measured to rotate once every 12 days (roughly twice as fast as the Sun). The reason for this is its youth; it is only about half a billion years old. Despite this young age, however, it has relatively low metallicity, particularly in iron. The visible spectrum is the portion of the optical spectrum (light or electromagnetic spectrum) that is visible to the human eye. ... A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies. ... In astronomy, the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ...


Its closest neighbour is Luyten 726-8 (UV Ceti and BL Ceti), 5.22 ly (1.60 pc) away. Luyten 726-8 is a binary star system that is one of Earths nearest neighbors. ... Luyten 726-8 is a binary star system that is one of Earths nearest neighbors. ... Luyten 726-8 is a binary star system that is one of Earths nearest neighbors. ...

Contents

Dust disk

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. 1988 (MCMLXXXVIII) was a leap year starting on Friday of the Gregorian calendar. ... Artists rendering of the Kuiper Belt and hypothetical more distant Oort cloud. ... For other uses, see Sun (disambiguation). ...


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. The astronomical unit (AU or au or a. ... The eight planets and three dwarf planets of the Solar System. ...

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. Furthermore, the low metallicity (roughly half that of the solar system) in the system reduces the odds of planet formation. If terrestrial planets do exist, however, for liquid water to exist on the surface, the planet would have to be around 0.53 AU from the star. For other uses, see Sun (disambiguation). ... Any planet is an extremely faint light source compared to its parent star. ...


Epsilon Eridani b

Epsilon Eridani b
Orbital elements
Semi-major axis (a) 3.39 ± 0.36 AU
Eccentricity (e) 0.702 ± 0.039
Orbital period (P) 2502 ± 10 d
Inclination (i) 30.1 ± 3.8°
Longitude of
periastron
(ω) 34°
Time of periastron (τ) −869.74 JD
Physical characteristics
Mass 1.55 ± 0.24 MJ
Radius  ? RJ
Density  ? kg/
Temperature  ? K
Discovery
Discovery date 2000
Detection method(s) Radial velocity
Discoverer(s) Hatzes et al.

Epsilon Eridani b is an 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. The semi-major axis of an ellipse In geometry, the term semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae. ... The astronomical unit (AU or au or a. ... In astrodynamics, under standard assumptions any orbit must be of conic section shape. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... Water, Rabbit, and Deer: three of the 20 day symbols in the Aztec calendar, from the Aztec Sun Stone. ... Inclination in general is the angle between a reference plane and another plane or axis of direction. ... In astrodynamics, the longitude of the periapsis (symbolized ) of an orbiting body is the longitude (measured from the point of the vernal equinox) of periapsis (closest approach to the central body). ... A diagram of Keplerian orbital elements. ... A diagram of Keplerian orbital elements. ... The Julian day or Julian day number (JDN) is the (integer) number of days that have elapsed since Monday, January 1, 4713 BC in the proleptic Julian calendar [1]. That day is counted as Julian day zero. ... Unsolved problems in physics: What causes anything to have mass? Mass is a property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... Adjective Jovian Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ... In classical geometry, a radius of a circle or sphere is any line segment from its center to its boundary. ... Adjective Jovian Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ... Density (symbol: ρ - Greek: rho) is a measure of mass per volume. ... The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. It was assigned to the United States in 1889 and is periodically recertified and traceable to the primary international standard, The Kilogram, held at the Bureau International des Poids et... The cubic meter (symbol m³) is the SI derived unit of volume. ... Fig. ... The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero—the lowest possible temperature where nothing could be colder and no heat energy remains in a substance—is defined as zero kelvin (0 K). ... This article is about the year 2000. ... An extrasolar planet, or exoplanet, is a planet beyond the Solar System. ... An extrasolar planet, or exoplanet, is a planet beyond the Solar System. ... This article is about the year 2000. ... Adjective Jovian Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ... The astronomical unit (AU or au or a. ... In astrodynamics, under standard assumptions any orbit must be of conic section shape. ... Image:Geoff marcy. ...


Observations by the Hubble Space Telescope have confirmed the existence of this planet. The estimated mass is 1.5 times Jupiter's mass, and the orbit is inclined by an angle of 30° from our line of sight. This orbital inclination is parallel to the observed dust ring around the star. The planet is expected to reach periapsis in 2007, when it could potentially be observed by the Hubble telescope.[1] The Hubble Space Telescope (HST) is a telescope in orbit around the Earth, named after astronomer Edwin Hubble for his discovery of galaxies outside the Milky Way and his creation of Hubbles Law, which calculates the rate at which the universe is expanding. ... Adjective Jovian Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ...

Epsilon Eridani c

Epsilon Eridani c
Orbital elements
Semi-major axis (a) ~40 AU
Eccentricity (e) ~0.3
Orbital period (P) ~280 y
Inclination (i)  ?°
Longitude of
periastron
(ω)  ?°
Time of periastron (τ) -869.74 JD
Physical characteristics
Mass ~0.1 MJ
Radius  ? RJ
Density  ? kg/
Temperature  ? K
Discovery
Discovery date 2002
Detection method(s) Analysis of dust disk
Discoverer(s) Quillen, Thorndike

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. The semi-major axis of an ellipse In geometry, the term semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae. ... The astronomical unit (AU or au or a. ... In astrodynamics, under standard assumptions any orbit must be of conic section shape. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... Inclination in general is the angle between a reference plane and another plane or axis of direction. ... In astrodynamics, the longitude of the periapsis (symbolized ) of an orbiting body is the longitude (measured from the point of the vernal equinox) of periapsis (closest approach to the central body). ... A diagram of Keplerian orbital elements. ... A diagram of Keplerian orbital elements. ... The Julian day or Julian day number (JDN) is the (integer) number of days that have elapsed since Monday, January 1, 4713 BC in the proleptic Julian calendar [1]. That day is counted as Julian day zero. ... Unsolved problems in physics: What causes anything to have mass? Mass is a property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... Adjective Jovian Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ... In classical geometry, a radius of a circle or sphere is any line segment from its center to its boundary. ... Adjective Jovian Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ... Density (symbol: ρ - Greek: rho) is a measure of mass per volume. ... The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. It was assigned to the United States in 1889 and is periodically recertified and traceable to the primary international standard, The Kilogram, held at the Bureau International des Poids et... The cubic meter (symbol m³) is the SI derived unit of volume. ... Fig. ... The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero—the lowest possible temperature where nothing could be colder and no heat energy remains in a substance—is defined as zero kelvin (0 K). ... For album titles with the same name, see 2002 (album). ... An extrasolar planet, or exoplanet, is a planet beyond the Solar System. ... See also: List of hypothetical planetary bodies A hypothetical planet is a planet whose existence is not known, but has been inferred from observational scientific evidence. ... For album titles with the same name, see 2002 (album). ... In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other. ... 2006 is a common year starting on Sunday of the Gregorian calendar. ...

Also of note is that the Epsilon Eridani system figures prominently in the Halo video game series. It is home to the planet Reach which housed major military complexes and shipyards in the 26th century.


See also

The star Epsilon Eridani, being a sunlike star relatively close to the solar system, is frequently used as a setting in works of science fiction. ... This list of the nearest stars to Earth is ordered by increasing distance out to a maximum of 5 parsecs (16. ...

Footnotes and references

  1. ^ "Hubble Zeroes in on Nearest Known Exoplanet", Hubble News Desk, 2006-10-09. Retrieved on 2006-10-10.

2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... October 10 is the 283rd day of the year (284th in Leap years). ... Sallie Baliunas is at the Harvard-Smithsonian Center for Astrophysics in the Solar, Stellar, and Planetary Sciences Division and formerly Deputy Director of the Mount Wilson Institute. ... Willie Soon (Wei-Hock Soon) is an astrophysicist at the Solar and Stellar Physics Division of the Harvard-Smithsonian Center for Astrophysics. ... February 1 is the 32nd day of the year in the Gregorian Calendar. ... The Astrophysical Journal is one of the foremost research journals devoted to recent developments, discoveries, and theories in astronomy and astrophysics. ... March 24 is the 83rd day of the year in the Gregorian Calendar (84th in leap years). ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... 1988 (MCMLXXXVIII) was a leap year starting on Friday of the Gregorian calendar. ... The Astrophysical Journal is one of the foremost research journals devoted to recent developments, discoveries, and theories in astronomy and astrophysics. ... For album titles with the same name, see 2002 (album). ... The Astrophysical Journal is one of the foremost research journals devoted to recent developments, discoveries, and theories in astronomy and astrophysics. ...

External links


  Results from FactBites:
 
Epsilon Eridani (632 words)
Epsilon Eridani has been the target of intense scrutiny by SETI projects, including the first, Project Ozma.
Moreover, Epsilon Eri provides a window into what conditions may have been like in the neighborhood of the Sun at a time when life was first beginning to emerge on the young Earth.
The presence of Epsilon Eridani C was disclosed by researchers at the University of Rochester using a new technique that does not use direct light from the star, but rather light radiating from the dust surrounding it.
Joint Astronomy Centre - Astronomers discover a nearby star system just like our own Solar System (1340 words)
Epsilon Eridani is marked by the star symbol, although the star itself is not seen at submillimetre wavelengths.
Epsilon Eridani is clearly visible to the naked eye, in the constellation Eridanus (the River), which stretches from the foot of Orion (near the bright star Rigel) to the 9th brightest star in the sky, the southerly Achernar (barely visible from the USA and Europe).
Epsilon Eridani is believed to be only 500 million years to 1 billion years old; our Sun is estimated to be 4.5 billion years old, and its inner region is believed to have looked very similar at that age.
  More results at FactBites »

 
 

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