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Theta Eridani
Theta Eridani, Romanization of Greek, Latinized from θ Eridani, is a binary star, binary system in the constellation of Eridanus (constellation), Eridanus with a combined apparent magnitude of 2.88. Its two components are designated θ1 Eridani, formally named Acamar (the traditional name of the system), and θ2 Eridani. The system's distance from the Sun based on stellar parallax, parallax measurements is approximately 165 light-years. Nomenclature Theta Eridani is the system's Bayer designation; θ1 and θ2 Eridani those of its two components. The system bore the traditional name Acamar, derived from the Arabic آخِر النَّهْر ''Ākhir an-nahr'', which means "the end of the river", via a Roman-alphabet handwriting misread "rn" to "m". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eridanus (constellation)
Eridanus is a constellation which stretches along the southern celestial hemisphere. It is represented as a river. One of the 48 constellations listed by the 2nd century AD astronomer Ptolemy, it remains one of the 88 modern constellations. It is the List of constellations by area, sixth largest of the modern constellations. The same name was later taken as a Latin name for the real Po River and also for the name of a Eridanos (Athens), minor river in Athens. Features Stars At its southern end is the apparent magnitude, 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 E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Etymology
Etymology ( ) is the study of the origin and evolution of words—including their constituent units of sound and meaning—across time. In the 21st century a subfield within linguistics, etymology has become a more rigorously scientific study. Most directly tied to historical linguistics, philology, and semiotics, it additionally draws upon comparative semantics, morphology, pragmatics, and phonetics in order to attempt a comprehensive and chronological catalogue of all meanings and changes that a word (and its related parts) carries throughout its history. The origin of any particular word is also known as its ''etymology''. For languages with a long written history, etymologists make use of texts, particularly texts about the language itself, to gather knowledge about how words were used during earlier periods, how they developed in meaning and form, or when and how they entered the language. Etymologists also apply the methods of comparative linguistics to reconstruct in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 24072
HD may refer to: Business * H-D or Harley-Davidson, a motorcycle manufacturer * The Home Depot, NYSE stock symbol: HD Chemistry * Hydrogen deuteride, a diatomic compound of hydrogen and deuterium * Mustard gas Codes * Air Do, formerly Hokkaido International Airlines, IATA designator * HD postcode area, covering Huddersfield, Brighouse and Holmfirth in England, UK * Heidelberg's vehicle registration plate code * Hunedoara County (Romania)'s ISO 3166 code Medicine * Hansen's disease or leprosy * Hirschsprung's disease, a disorder of the abdomen * Huntington's disease, a genetic disorder affecting the central nervous system ** HD (gene) or huntingtin, the IT15 gene, which codes for the huntingtin protein People * H.D. or Hilda Doolittle (1886–1961), American poet and novelist Other uses * ''Helsingborgs Dagblad'', a Swedish newspaper * Henry Draper Catalogue, an astronomical catalogue often used to designate stars * Department of Highways (other) * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 23319
h Eridani (HD 23319) is an orange-hued star in the constellation Eridanus. It has an apparent visual magnitude of 4.59, which make it faintly visible to the naked eye in skies with low light pollution. The distance to HD 23319 can be estimated from its annual parallax shift of , which yields a distance of about 176 light years. It is moving further away from the Earth with a heliocentric radial velocity of +9.9 km/s. This is an aging giant star with a stellar classification of , where the suffix notation indicates the spectrum shows a mild overabundance of the cyano radical. It is a red clump giant, indicating it is on the horizontal branch and is generating energy through helium fusion at its core. The star has 1.4 times the mass of the Sun and, at the age of 3.2 billion years, has expanded to 11 times the Sun's radius. It is radiating 51 times the Sun's luminosity from its enlarged photosphere at an effective temperature The effective temperatur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 16754
HD 16754 is a binary or triple-star system in the constellation Eridanus. It has the Bayer designation s Eridani; ''HD 16754'' is the designation from the ''Henry Draper catalogue''. The system is visible to the naked eye as a faint point of light with an apparent visual magnitude of +4.74. It is located at a distance of approximately 132 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +18 km/s. The system is a member of the Columba association of co-moving stars. This object was flagged as an astrometric binary based on proper motion measurements made from the Hipparcos spacecraft. Zuckerman et al. (2011) consider it a multi-star system, with a bright A-type primary plus a faint M-type companion at an angular separation of to the north. The astrometric companion to the primary remains unresolved. The main component is an A-type main-sequence star with a stellar classification of A1 Vb. Based upon s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kappa Eridani
Kappa Eridani, Latinized from κ Eridani, is a solitary star in the constellation Eridanus. With an apparent visual magnitude of 4.25, it is bright enough to be visible to the naked eye on a dark night. Based upon an annual parallax shift of 0.00642 arc seconds, it is roughly 510 light years distant from the Sun. This appears to be an evolving B-type subgiant star with a stellar classification of B7 IV. The measured angular diameter is . At an estimated distance of Kappa Eridani, this yields a physical size of about six times the radius of the Sun. It has five times the Sun's mass, and radiates 1,175 times the solar luminosity from its outer atmosphere at an effective temperature of 14,700 K. Kappa Eridani is spinning with a projected rotational velocity Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surfa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phi Eridani
φ Eridani (Latinised as Phi Eridani) is a star in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.55. The distance to this star, as determined using the parallax method, is around 154 light-years. This is a B-type star with a stellar classification of B8IV-V, suggesting it shows traits of a main-sequence star and a subgiant. It is spinning rapidly with a projected rotational velocity of 250 km/s. This rotation is giving the star an oblate shape with an equator that is 17% larger than the polar radius. It has 3.55 times the mass of the Sun and radiates 135 times the solar luminosity from its outer atmosphere at an effective temperature of about 12,650 K. Phi Eridani may form a wide binary star system with a 9th-magnitude star at lies an angular separation of 86″. This companion is a G-type main-sequence star A G-type main-sequence star (spectral type: G-V), also often, and imprecisely, called a yel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chi Eridani
χ Eridani (Latinised as Chi Eridani) is a binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 3.70. The distance to this system, as determined using the parallax method, is around 58 light years. The pair had an angular separation of 5.0 arcseconds as of 1994. This corresponds to a projected separation of around 128 AU. The primary component is an evolving G-type subgiant star with a stellar classification of G8 IV. It is about 1.6 times the mass of the Sun and has 4 times the Sun's radius. The star shines with 10 times the solar luminosity from its outer atmosphere at an effective temperature The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation. Effective temperature is often used as an estimate of a body's surface temperature ... of 5,115 K. Unusually for a star ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asterism (astronomy)
An asterism is an observational astronomy, observed pattern or group of stars in the sky. Asterisms can be any identified star pattern, and therefore are a more general concept than the IAU designated constellations, 88 formally defined constellations. Constellations are based upon asterisms, but unlike asterisms, constellations are defined regions with official boundaries which together encompass the entire sky. 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. The patterns of stars seen in asterisms are not necessarily a product of any physical association between the stars, but are rather the result of the particular perspectives of their observ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Net (Chinese Constellation)
The Net mansion () is one of the Twenty-eight mansions of the Chinese constellations. It is one of the western mansions of the White Tiger. Asterisms References {{DEFAULTSORT:Net (Chinese Constellation) Chinese constellations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chinese Astronomy
Astronomy in China has a long history stretching from the Shang dynasty, being refined over a period of more than 3,000 years. The Ancient China, ancient Chinese people have identified stars from 1300 BCE, as Chinese star names later categorized in the twenty-eight mansions have been found on oracle bones unearthed at Anyang, dating back to the mid-Shang dynasty. The core of the "mansion" (宿 ''xiù'') system also took shape around this period, by the time of King Wu Ding (1250–1192 BCE). Detailed records of astronomical observations began during the Warring States period (fourth century BCE). They flourished during the Han period (202 BCE – 220 CE) and subsequent dynasties with the publication of star catalogues. Chinese astronomy was equatorial, centered on close observation of circumpolar stars, and was based on different principles from those in traditional Western astronomy, where heliacal risings and settings of zodiac constellations formed the basic ecliptic framew ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ptolemy
Claudius Ptolemy (; , ; ; – 160s/170s AD) was a Greco-Roman mathematician, astronomer, astrologer, geographer, and music theorist who wrote about a dozen scientific treatises, three of which were important to later Byzantine science, Byzantine, Islamic science, Islamic, and Science in the Renaissance, Western European science. The first was his astronomical treatise now known as the ''Almagest'', originally entitled ' (, ', ). The second is the ''Geography (Ptolemy), Geography'', which is a thorough discussion on maps and the geographic knowledge of the Greco-Roman world. The third is the astrological treatise in which he attempted to adapt horoscopic astrology to the Aristotelian physics, Aristotelian natural philosophy of his day. This is sometimes known as the ' (, 'On the Effects') but more commonly known as the ' (from the Koine Greek meaning 'four books'; ). The Catholic Church promoted his work, which included the only mathematically sound geocentric model of the Sola ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
