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ζ Ceti
Zeta Ceti (ζ Ceti, abbreviated Zeta Cet, ζ Cet) is a binary star in the equatorial constellation of Cetus. It has a combined apparent visual magnitude of 3.74, which is bright enough to be seen with the naked eye. Based upon parallax measurements taken during the Hipparcos mission, it is approximately 235 light-years from the Sun. Zeta Ceti is the primary or 'A' component of a double star system designated WDS J01515-1020 (the secondary or 'B' component is HD 11366). Zeta Ceti's two components are therefore designated WDS J01515-1020 Aa and Ab. Aa is officially named Baten Kaitos , the traditional name of the entire system. Nomenclature ''ζ Ceti'' ( Latinised to ''Zeta Ceti'') is the binary pair's Bayer designation. WDS J01515-1020 A is its designation in the Washington Double Star Catalog. The designations of the two components as WDS J01515-1020 Aa and Ab derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
J2000
In astronomy, an epoch or reference epoch is a moment in time used as a reference point for some time-varying astronomical quantity. It is useful for the celestial coordinates or orbital elements of a celestial body, as they are subject to perturbations and vary with time. These time-varying astronomical quantities might include, for example, the mean longitude or mean anomaly of a body, the node of its orbit relative to a reference plane, the direction of the apogee or aphelion of its orbit, or the size of the major axis of its orbit. The main use of astronomical quantities specified in this way is to calculate other relevant parameters of motion, in order to predict future positions and velocities. The applied tools of the disciplines of celestial mechanics or its subfield orbital mechanics (for predicting orbital paths and positions for bodies in motion under the gravitational effects of other bodies) can be used to generate an ephemeris, a table of values giving ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Double Star
In observational astronomy, a double star or visual double is a pair of stars that appear close to each other as viewed from Earth, especially with the aid of optical telescopes. This occurs because the pair either forms a binary star (i.e. a binary system of stars in mutual orbit, gravitationally bound to each other) or is an ''optical double'', a chance line-of-sight alignment of two stars at different distances from the observer. Binary stars are important to stellar astronomers as knowledge of their motions allows direct calculation of stellar mass and other stellar parameters. The only (possible) case of "binary star" whose two components are separately visible to the naked eye is the case of Mizar and Alcor (though actually a multiple-star system), but it is not known for certain whether Mizar and Alcor are gravitationally bound. Since the beginning of the 1780s, both professional and amateur double star observers have telescopically measured the distances and angles be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Andromedae
Gamma Andromedae is a multiple star system in the northern constellation of Andromeda. It is the third-brightest star in the constellation, after Alpheratz and Mirach. Its identifier is a Bayer designation that is Latinized from γ Andromedae, and is abbreviated Gam1 And or γ1 And, respectively. The system has the proper name Almach, pronounced . Based on parallax measurements, it is estimated to be about 390 light-years distant. The system is drifting closer to the Sun with a radial velocity of . Observation In 1778, German physicist Johann Tobias Mayer discovered that γ Andromedae is a double star. When examined in a small telescope, it appears to be a bright, golden-yellow star next to a dimmer, indigo-blue star, separated by approximately 10 arcseconds. The pair is often considered by stargazers to be a beautiful double star with a striking contrast of color. The brighter member, γ1 Andromedae, is the primary of the system, and is th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upsilon Ceti
Upsilon Ceti, Latinized from υ Ceti, is a solitary star in the equatorial constellation of Cetus. It is visible to the naked eye with an apparent visual magnitude of 3.95. Based upon an annual parallax shift of 11.14 mas, it is located about 293 light years from the Sun. This star was designated Upsilon Ceti by Bayer and 59 Ceti by Flamsteed. Flamsteed also gave it the designation Upsilon2 Ceti to distinguish it from 56 Ceti, which he called Upsilon1. Flamsteed's superscripted designations, however, are not in general use today. For ancient Arabic astronomers, this star with η Cet (Deneb Algenubi), θ Cet (Thanih al Naamat), τ Cet and ζ Cet (Baten Kaitos), formed Al Naʽāmāt (النعامات), the Hen Ostriches In Chinese, (), meaning ''Sickle'', refers to an asterism consisting of υ Ceti, 48 Ceti and 56 Ceti. Consequently, the Chinese name for υ Ceti itself is (, .) [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau Ceti
Tau Ceti, Latinized from τ Ceti, is a single star in the constellation Cetus that is spectrally similar to the Sun, although it has only about 78% of the Sun's mass. At a distance of just under from the Solar System, it is a relatively nearby star and the closest solitary G-class star. The star appears stable, with little stellar variation, and is metal-deficient (low in elements other than hydrogen and helium) relative to the Sun. It can be seen with the unaided eye with an apparent magnitude of 3.5. As seen from Tau Ceti, the Sun would be in the northern hemisphere constellation Boötes with an apparent magnitude of about 2.6.From Tau Ceti the Sun would appear on the diametrically opposite side of the sky at the coordinates RA = , Dec = , which is located near Tau Boötis. The absolute magnitude of the Sun is 4.8, so, at a distance of , the Sun would have an apparent magnitude m = M_v + 5 \cdot (\log_ 3.64 - 1) = 2.6. Observations have dete ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theta Ceti
Theta Ceti, Latinized from θ Ceti, is a solitary, orange-hued star in the equatorial constellation of Cetus. It is visible to the naked eye with an apparent visual magnitude of 3.60. Based upon an annual parallax shift of 20.04 mas as seen from Earth, it is located about 113 light-years from the Sun. At that distance, the visual magnitude is diminished by an extinction factor of 0.28 due to interstellar dust. With an age of about 2.2 billion years, this is an evolved, K-type giant star with a stellar classification of K0 III. It is a red clump star on the horizontal branch, which means it is generating energy through helium fusion at its core. The star has an estimated 1.8 times the mass of the Sun and has expanded to 10 times the Sun's radius. It is radiating 58 times the solar luminosity from its photosphere at an effective temperature of 4,951 K. Name In the catalogue of stars in the ''Calendarium of Al Achsasi Al Mouakket'', this star was desi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eta Ceti
Eta Ceti (η Cet, η Ceti) is a star in the equatorial constellation of Cetus. It has the traditional name Deneb Algenubi or Algenudi. The apparent visual magnitude of this star is +3.4, making it the fourth-brightest star in this otherwise relatively faint constellation. The distance to this star can be measured directly using the parallax technique, yielding a value of . This is a giant star that has been chosen a standard for the stellar classification of K2−IIIb. It has exhausted the hydrogen at its core and evolved away from the main sequence of stars like the Sun. (The classification is sometimes listed as K1.5 IIICN1Fe0.5, indicating a strong CN star with higher-than-normal abundance of cyanogen and iron relative to other stars of its class.) It is probably on the red giant branch fusing hydrogen in a shell, although there is a possibility that it is a red clump star that is generating energy through the nuclear fusion of helium at its core. Eta Ceti has ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latin
Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area around Rome, Italy. Through the expansion of the Roman Republic, it became the dominant language in the Italian Peninsula and subsequently throughout the Roman Empire. It has greatly influenced many languages, Latin influence in English, including English, having contributed List of Latin words with English derivatives, many words to the English lexicon, particularly after the Christianity in Anglo-Saxon England, Christianization of the Anglo-Saxons and the Norman Conquest. Latin Root (linguistics), roots appear frequently in the technical vocabulary used by fields such as theology, List of Latin and Greek words commonly used in systematic names, the sciences, List of medical roots, suffixes and prefixes, medicine, and List of Latin legal terms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Al Achsasi Al Mouakket
Muḥammad al Achsasi al Mouakket () was a 17th century Egyptian astronomer whose and catalogue of stars, ("''Pearls of brilliance upon the solar operations''"), was written in Cairo in about 1650. Al-Achsasi was a shaykh, a learned elder, of the Grand Mosque of the university of Cairo, where his name reflected his position in regulating the times and hours at the mosque. connects him in origin to a village in the Faiyum, southwest of Cairo. No copies of al-Achsasi's book were known to Western astronomers or historians of science until 1895, when the incomplete manuscript was obtained by the amateur English astronomer Edward Ball Knobel; thus al-Achsasi did not appear in the standard French and English bibliographies and library catalogues of the 19th century. Knobel announced his discovery of the work in the journal of the Royal Astronomical Society The Royal Astronomical Society (RAS) is a learned society and charitable organisation, charity that encourages and promote ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiple Star
A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. It may sometimes be used to refer to a single star. A large group of stars bound by gravitation is generally called a ''star cluster'' or ''galaxy'', although, broadly speaking, they are also star systems. Star systems are not to be confused with planetary systems, which include planets and similar bodies (such as comets). Terminology A star system of two stars is known as a ''binary star'', ''binary star system'' or ''physical double star''. Systems with four or more components are rare, and are much less commonly found than those with 2 or 3. Multiple-star systems are called ''triple'', ''ternary'', or ''trinary'' if they contain three stars; ''quadruple'' or ''quaternary'' if they contain four stars; ''quintuple'' or ''quintenary'' with five stars; ''sextuple'' or ''sextenary'' with six stars; ''septuple'' or ''septenary'' with seven stars; and ''octuple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IAU Working Group On Star Names
The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education, Outreach and Heritage. The IAU states that it is keen to make a distinction between the terms ''name'' and ''designation''. To the IAU, ''name'' refers to the (usually colloquial) term used for a star in everyday conversation, while ''designation'' is solely alphanumerical, and used almost exclusively in official catalogues and for professional astronomy. (The WGSN notes that transliterated Bayer designations (e.g., Tau Ceti) are considered a special historical case and are treated as designations.) Terms of reference The terms of reference for the WGSN for the period 2016–2018 were approved by the IAU Executive Committee at its meeting on 6 May 2016. In summary, these are to: * establish IAU guidelines for the proposal and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arabic
Arabic (, , or , ) is a Central Semitic languages, Central Semitic language of the Afroasiatic languages, Afroasiatic language family spoken primarily in the Arab world. The International Organization for Standardization (ISO) assigns language codes to 32 varieties of Arabic, including its standard form of Literary Arabic, known as Modern Standard Arabic, which is derived from Classical Arabic. This distinction exists primarily among Western linguists; Arabic speakers themselves generally do not distinguish between Modern Standard Arabic and Classical Arabic, but rather refer to both as ( "the eloquent Arabic") or simply ' (). Arabic is the List of languages by the number of countries in which they are recognized as an official language, third most widespread official language after English and French, one of six official languages of the United Nations, and the Sacred language, liturgical language of Islam. Arabic is widely taught in schools and universities around the wo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
