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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 star Al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
J2000
In astronomy, an epoch or reference epoch is a instant, 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 Astronomical object, celestial body, as they are subject to Perturbation (astronomy), 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 Perihelion and aphelion, 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 bodi ... [...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 or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 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 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 (possessive) form. The constellation name is frequently abbreviated to a standard three-letter form. For example, Aldebaran in the constellation ... [...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 variati ... [...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 Ulug 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 of n ... [...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] |
Purple Forbidden Enclosure
The Purple Forbidden enclosure ( Zǐ wēi yuán) is one of the San Yuan ( Sān yuán) or Three Enclosures Traditional Chinese astronomy has a system of dividing the celestial sphere into asterisms or constellations, known as "officials" ( Chinese ''xīng guān''). The Chinese asterisms are generally smaller than the constellations of Hellenistic .... 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 References Chinese constellations Chinese astrology {{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 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) and flourished from the Han period onward. 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 framework. Joseph Needham has described the ancient Chinese as the most persistent and accurate obser ... [...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. 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). A star system of two stars is known as a ''binary star'', ''binary star system'' or ''physical double star''. If there are no tidal effects, no perturbation from other forces, and no transfer of mass from one star to the other, such a system is stable, and both stars will trace out an elliptical orbit around the barycenter of the system indefinitely. ''(See Two-body problem)''. Examples of binary systems are Sirius, Procyon and Cygnus X-1, the last of which probably consists of a star and a black hole. Multiple star systems A multiple star system consists of three or more stars that appear f ... [...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 (Athebyne). The faint pair Omega Draconis Omega Draconis, Latinized from ω Draconis and also known as 28 Draconis, is a binary star in the constellation of Draco. The system is fairly close, and is located about 76 light-years (23 parsecs) away, based on its parallax. Omega Dra ... and 27 Draconis was known as the "wolf's claws" (الأظفار الذئب ... [...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'' this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arabic
Arabic (, ' ; , ' or ) is a Semitic languages, Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C. E.Watson; Walter de Gruyter GmbH & Co. KG, Berlin/Boston, 2011. Having emerged in the 1st century, it is named after the Arabs, Arab people; the term "Arab" was initially used to describe those living in the Arabian Peninsula, as perceived by geographers from ancient Greece. Since the 7th century, Arabic has been characterized by diglossia, with an opposition between a standard Prestige (sociolinguistics), prestige language—i.e., Literary Arabic: Modern Standard Arabic (MSA) or Classical Arabic—and diverse vernacular varieties, which serve as First language, mother tongues. Colloquial dialects vary significantly from MSA, impeding mutual intelligibility. MSA is only acquired through formal education and is not spoken natively. It is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
