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Eta Draconis
Eta Draconis (η Draconis, abbreviated Eta Dra, η Dra) is a binary star in the northern circumpolar constellation of Draco. Despite having an apparent visual magnitude of only +2.73, it is the second-brightest star in this generally faint constellation. Based upon parallax measurements collected during the Hipparcos mission, this star is located at a distance of about from the Sun. The two components are designated Eta Draconis A (also named Athebyne ) and B. Nomenclature ''η Draconis'' ( Latinised to ''Eta Draconis'') is the system's Bayer designation. The designations of the two components as ''Eta Draconis A'' and ''B'' derives from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU). Eta Draconis, together with Zeta Draconis, bore the traditional Arabic name الذئبين ''al-dhiʼbayn'', "the (two) wolves", lying in wait for the camel's foal, the little sta ... [...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] |
Bayer Designation
A Bayer designation is a stellar designation in which a specific star is identified by a Greek alphabet, Greek or Latin letter followed by the genitive case, genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1564 stars. The brighter stars were assigned their first systematic names by the German astronomer Johann Bayer in 1603, in his star atlas ''Uranometria''. Bayer catalogued only a few stars too far south to be seen from Germany, but later astronomers (including Nicolas-Louis de Lacaille and Benjamin Apthorp Gould) supplemented Bayer's catalog with entries for southern constellations. Scheme Bayer assigned a lowercase Greek alphabet, Greek letter (alpha (α), beta (β), gamma (γ), etc.) or a Latin letter (A, b, c, etc.) to each star he catalogued, combined with the Latin name of the star's parent constellation in genitive case, genitive (possessive) form. The constellation name is frequently abbreviated to a standard three ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theta Draconis
Theta Draconis, a name Latinized from θ Draconis, is a binary star system in the northern circumpolar constellation of Draco. It is faintly visible to the naked eye at night with an apparent visual magnitude of 4.12. Parallax measurements place it at an estimated distance of from the Sun, and it is drifting closer with a radial velocity of −8 km/s. It has a relatively high proper motion, traversing the celestial sphere at the rate of per year. O. J. Eggen included this star as a member of the NGC 1901 supercluster based on its space motion. The binary nature of this system was discovered by W. W. Campbell in 1899, and the first set of orbital elements was published by H. D. Curtis in 1907. It is a single-lined spectroscopic binary in a close orbit with a period of 3.07 days and an eccentricity (ovalness) of 0.04. The secondary component has been resolved in the infrared H band, allowing an estimation of the mass ratio as . Some velocity variation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iota Draconis
Iota Draconis (ι Draconis, abbreviated Iota Dra, ι Dra), also named Edasich , is a star in the northern circumpolar constellation of Draco. A visually unremarkable star of apparent magnitude 3.3, in 2002 it was discovered to have a planet orbiting it (designated Iota Draconis b, later named Hypatia). From parallax measurements, this star is located at a distance of about from the Sun. Nomenclature ''ι Draconis'' ( Latinised to ''Iota Draconis'') is the star's Bayer designation. On discovery the planet was designated Iota Draconis b (or Edasich b). It bore the traditional name ''Edasich'', derived from the Arabic ' of Ulugh Beg and the Dresden Globe, or 'Male hyena' by Kazwini, with ''Eldsich'' being recorded in the ''Century Cyclopedia''. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches o ... [...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] |
Purple Forbidden Enclosure
The Purple Forbidden enclosure ( Zǐ wēi yuán) is one of the San Yuan ( Sān yuán) or Three Enclosures. Stars and constellations of this group lie near the north celestial pole and are visible all year from temperate latitudes in the Northern Hemisphere. Asterisms The asterisms are: See also * Twenty-Eight Mansions The Twenty-Eight Mansions (), also called or , are part of the Chinese constellations system. They can be considered as the equivalent to the Zodiac, zodiacal constellations in Western astronomy, though the Twenty-eight Mansions reflect the move ... References Chinese constellations Chinese astrology Purple {{china-stub ... [...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] |
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] |
Mother Camels
The protecting Mother Camels (Arabic العوائذ ''alʽawaʼid'') is an asterism in the constellation of Draco described by ancient Arabic nomadic tribes. The asterism was interpreted as a ring of mother camels – Beta Draconis (Rastaban), Gamma Draconis (Eltanin), Nu Draconis (Kuma) and Xi Draconis (Grumium) – surrounding a foal (the faint star Alruba), with another mother camel, Mu Draconis (Alrakis) running to join them. The Arabs did not see the constellation Draco as it is now. The Mother Camels were protecting the foal from the attack of two wolves or jackals – Zeta Draconis (Aldhibah) and Eta Draconis Eta Draconis (η Draconis, abbreviated Eta Dra, η Dra) is a binary star in the northern circumpolar constellation of Draco. Despite having an apparent visual magnitude of only +2.73, it is the second-brightest star in this generally f ... (Athebyne). The faint pair Omega Draconis and 27 Draconis was known as the "wolf's claws" (الأظفار ا� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alruba
Alruba, a name derived from Arabic for "the foal", is a suspected astrometric binary star system in the northern circumpolar constellation of Draco. It is just barely visible to the naked eye as a dim point of light with an apparent visual magnitude of 5.76. Based on parallax measurements obtained during the Gaia mission, it is located at a distance of about from the Sun. The system is drifting closer with a radial velocity of −2 km/s. The visible component is an A-type main-sequence star with a stellar classification of A0 V. It is about 58 million years old with three times the mass of the Sun and has a high rate of spin, showing a projected rotational velocity of 170 km/s. The star is radiating 147 times the luminosity of the Sun from its photosphere at an effective temperature of 9,226 K. The system is a source for X-ray emission, which is most likely coming from the unseen companion. Nomenclature In the ''Henry Draper catalogue'' ... [...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] |
