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Eta Eridani
Eta Eridani (η Eridani, abbreviated Eta Eri, η Eri), officially named Azha (with a silent 'h', possibly ), is a giant star in the constellation of Eridanus. Based on parallax measurements taken during the Hipparcos mission, it is approximately 137 light-years from the Sun. Nomenclature ''η Eridani'' ( Latinised to ''Eta Eridani'') is the star's Bayer designation. It bore the traditional name ''Azha'', from the old Arab asterism نَعَام أُدْحِيّ ''udḥiyy al-naʽām'' "the ostrich nest" (or "hatching place"), which included Eta Eridani. The first word, ادحى ''udḥiyy'', was miscopied as ازحى (readable as ''azḥā'') in medieval manuscripts. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name ''Azha'' for this star on 12 September 2016 and it is now so included in the List of IAU-approved Star Names. In Chinese, (), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eridanus (constellation)
Eridanus () is a constellation in the southern celestial hemisphere. It is represented as a river. One of the 48 constellations listed by the 2nd century astronomer Ptolemy, it remains one of the 88 modern constellations. It is the sixth largest of the modern constellations, and the one that extends farthest in the sky from north to south. The same name was later taken as a Latin name for the real Po River and also for the name of a minor river in Athens. Features Stars At its southern end is the magnitude 0.5 star Achernar, designated Alpha Eridani. It is a blue-white hued main sequence star 144 light-years from Earth, whose traditional name means "the river's end". Achernar is a very peculiar star because it is one of the flattest stars known. Observations indicate that its radius is about 50% larger at the equator than at the poles. This distortion occurs because the star is spinning extremely rapidly. There are several other noteworthy stars in Eridanus, including ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asterism (astronomy)
An asterism is an observed pattern or group of stars in the sky. Asterisms can be any identified pattern or group of stars, and therefore are a more general concept than the formally defined 88 constellations. Constellations are based on asterisms, but unlike asterisms, constellations outline and today completely divide the sky and all its celestial objects into regions around their central asterisms. For example, the asterism known as the Big Dipper comprises the seven brightest stars in the constellation Ursa Major. Another is the asterism of the Southern Cross, within the constellation of Crux. Asterisms range from simple shapes of just a few stars to more complex collections of many stars covering large portions of the sky. The stars themselves may be bright naked-eye objects or fainter, even telescopic, but they are generally all of a similar brightness to each other. The larger brighter asterisms are useful for people who are familiarizing themselves with the night sky. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau7 Eridani
Tau7 Eridani is a solitary star in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 5.235. Using the parallax method, the distance to this star can be estimated as around 251 light years. This is an A-type main sequence star with a stellar classification of A3 Vs, where the 's' indicates it has narrow absorption lines. It may be a chemically peculiar Am star, which means it displays unusual abundances of certain elements in its surface layers. Tau7 Eridani appears to be a low amplitude variable that displays slight fluctuations in luminosity over a period of 7.17 days. It is slowly rotating with a projected rotational velocity of 18 km/s, and is around 387 million years old. References {{DEFAULTSORT:Tau7 Eridani A-type main-sequence stars Eridanus (constellation) Eridani, Tau7 Eridani, 28 023878 017717 1181 Year 1181 ( MCLXXXI) was a common year starting on Thursday (link will displ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau6 Eridani
Tau6 Eridani, Latinized from τ6 Eridani, is a single star in the equatorial constellation of Eridanus, located near the constellation border with Fornax. It has a yellow-white hue with an apparent visual magnitude of 4.22, which is bright enough to be seen with the naked eye. Based upon parallax measurements, the distance to this star is around 57.5 light years. It is drifting further away with a radial velocity of +8 km/s. The spectrum of Tau6 Eridani matches a stellar classification of F5IV-V, indicating it is an F-type star that shows traits of both a main sequence star and a subgiant. It has an estimated 135% of the Sun's mass and about 1.8 time the radius of the Sun. The star is radiating 5.5 times the luminosity of the Sun at an effective temperature of 6,508 K, and it does not display any surface magnetic activity. The star has been examined for infrared excess emission that could indicate the presence of circumstellar matter, but none has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau5 Eridani
Tau5 Eridani, Latinized from τ5 Eridani, is a binary star system in the constellation Eridanus. It is visible to the naked eye with a combined apparent visual magnitude of 4.26. The distance to this system, as estimated using the parallax technique, is around 293 light years. Tau5 Eridani is a double-lined spectroscopic binary system. The two stars orbit each other closely with a period of 6.2 days and an eccentricity of 0.2. On average, the two stars are separated by around 0.183 AU. The primary component is a B-type main sequence star with a stellar classification of B0 V. It is around 157 million years old and is spinning with a projected rotational velocity of 55 km/s. The star has around 3.3 times the mass of the Sun and 3.2 times the Sun's radius. It radiates 188 times the solar luminosity from an outer atmosphere at an effective temperature of 12,514 K. The secondary component has a stellar classification of B9&nb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau4 Eridani
Tau4 Eridani (τ4 Eridani, τ4 Eri) is a binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.65. The distance to this star can be estimated using the parallax method, which yields a value of roughly 300 light years. This is an evolved red giant star currently on the asymptotic giant branch with a stellar classification of M3/4 III. It is a slow irregular variable star of type Lb, undergoing changes in magnitude over the range 3.57−3.72 with a periodicity of 23.8 d. The measured angular diameter of Tau4 Eridani is . At its estimated distance, this yields a physical size of about 106 times the radius of the Sun. It shines with 1,537 times the luminosity of the Sun from an outer atmosphere at an effective temperature of 3,712 K. This is most likely a binary star system. The companion is a magnitude 9.5 star at an angular separation of 5.7 ″ along a position angle of 291°, as of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau3 Eridani
Tau3 Eridani, Latinized from τ3 Eridani, is a star in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 4.10. Using the parallax method, the distance to this star can be estimated as 88.6 light years. In 2001 it was reported as a candidate Vega-like star, meaning it appears to radiate an infrared excess from an orbiting circumstellar disk. However, this has not been confirmed. This is an A-type star with a stellar classification of A3 IV-V. The luminosity class of IV-V indicates the spectrum displays traits intermediate between a main sequence and subgiant star. It is around 476 million years old and is spinning rapidly with a projected rotational velocity of 133 km/s. This is creating an equatorial bulge that might be 7% wider than the polar radius. Tau3 Eridani has 178% of the Sun's mass and nearly double the radius of the Sun. The star shines with 13.7 times the solar luminosity The solar luminosity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau2 Eridani
Tau2 Eridani (τ2 Eridani, abbreviated Tau2 Eri, τ2 Eri), formally named Angetenar , is a star in the constellation of Eridanus. It is visible to the naked eye with an apparent visual magnitude of 4.78. The distance to this star, as determined via the parallax method, is around 187 light-years. Nomenclature ''τ2 Eridani'' ( Latinised to ''Tau2 Eridani'') is the system's Bayer designation. It is one of a series of stars that share the Bayer designation Tau Eridani. It bore the traditional name ''Angetenar'', derived from the Arabic ''Al Ḥināyat an-Nahr'', 'the Bend in the River', near which it lies. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name ''Angetenar'' for this star on 30 June 2017 and it is now so included in the List of IAU-approved Star Names. In Chinese, (), meaning '' Celestial Meadows'', refers to an asterism consisting of Tau2 Eridani, Gamma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau1 Eridani
Tau1 Eridani, Latinized from τ1 Eridani, is a binary star system in the constellation Eridanus. It has an apparent magnitude of 4.46, making it visible to the naked eye in suitably dark conditions. This a spectroscopic binary with an orbital period of 958 days. It is located about 46 light years from the Earth. At present, the system is moving away from the Sun with a radial velocity of +26 km/s. About 305,000 years ago, it made perihelion passage at an estimated distance of . Tau1 Eridani was a latter designation of 90 Ceti. Debris disk A moderate far-infrared excess was observed for this star system, in the 12μm, 25μm, 60μm and 100μm wavelengths, by the Infrared Astronomical Satellite The Infrared Astronomical Satellite (Dutch: ''Infrarood Astronomische Satelliet'') (IRAS) was the first space telescope to perform a survey of the entire night sky at infrared wavelengths. Launched on 25 January 1983, its mission lasted ten mon ... (IRAS), an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pi Ceti
Pi Ceti, Latinized from π Ceti, is the Bayer designation for a star system in the equatorial constellation of Cetus. It is visible to the naked eye with an apparent visual magnitude of 4.238. Observed to have an Earth half yearly parallax shift of 8.30 mas, it is around 393 light years from the Sun. This is a single-lined spectroscopic binary system with a nearly circular orbit and a period of 7.45 years. The fact that the system has a negligible eccentricity is surprising for such a long period, and may suggest that the secondary is a white dwarf that had its orbit circularized during a mass-transfer event. The primary, component A, is a normal B-type star that has been given stellar classifications of B7 V and B7 IV. It appears very young – less than half a million years in age – and may still be on a pre-main sequence track. The star shows no magnetic field but it does emit an infrared excess. Name This star, along with ε Cet, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zeta Eridani
Zeta Eridani (ζ Eridani, abbreviated Zeta Eri, ζ Eri) is a binary star in the constellation of Eridanus. With an apparent visual magnitude of 4.80, it is visible to the naked eye on a clear dark night. Based on parallax measurements taken during the Hipparcos mission, it is approximately 110 light-years from the Sun. Zeta Eridani is the primary or 'A' component of a multiple star system designated WDS J03158-0849 (the secondary or 'B' component is 14 Eridani). Zeta Eridani's two components are therefore designated WDS J03158-0849 Aa and Ab. Aa is formally named Zibal , the traditional name for the system. Nomenclature ''ζ Eridani'' ( Latinised to ''Zeta Eridani'') is the binary star's Bayer designation. WDS J03158-0849 A is its designation in the Washington Double Star Catalog. The designations of the two components as WDS J03158-0849 Aa and Ab derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and ado ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epsilon Eridani
Epsilon Eridani ( Latinized from ε Eridani), formally named Ran, is a star in the southern constellation of Eridanus, at a declination of 9.46° south of the celestial equator. This allows it to be visible from most of Earth's surface. At a distance of from the Sun, it has an apparent magnitude of 3.73. It is the third-closest individual star or star system visible to the unaided eye. The star is estimated to be less than a billion years old. Because of its relative youth, Epsilon Eridani has a higher level of magnetic activity than the present-day Sun, with a stellar wind 30 times as strong. Its rotation period is 11.2 days at the equator. Epsilon Eridani is smaller and less massive than the Sun, and has a comparatively lower level of elements heavier than helium. It is a main-sequence star of spectral class K2, which means that energy generated at the core through nuclear fusion of hydrogen is emitted from the surface at a temperature of about , giving it an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
