|
Nu Boötis
The Bayer designation Nu Boötis (ν Boo / ν Boötis) is shared by two star systems, in the constellation Boötes: * ν¹ Boötis * ν² Boötis They are separated by 0.17° on the sky. They have almost identical visual magnitudes, but contrasting colours: ν1 is a yellow giant star, while ν2 is a close binary with two white main sequence stars. Both stars were members of asterism 七公 (Qī Gōng), ''Seven Excellencies'', ''Heavenly Market enclosure''. Ptolemy considered Nu Boötis to be shared by Hercules, and Bayer Bayer AG (, commonly pronounced ; ) is a German multinational pharmaceutical and biotechnology company and one of the largest pharmaceutical companies in the world. Headquartered in Leverkusen, Bayer's areas of business include pharmaceutica ... assigned it a designation in both constellations: Nu Boötis (ν Boo) and Psi Herculis (ψ Her). When the modern constellation boundaries were fixed in 1930, the latter designation dropped from use. Referenc ... [...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] |
Star System
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 t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the earliest constellations likely go back to prehistory. People used them to relate stories of their beliefs, experiences, creation, or mythology. Different cultures and countries adopted their own constellations, some of which lasted into the early 20th century before today's constellations were internationally recognized. The recognition of constellations has changed significantly over time. Many changed in size or shape. Some became popular, only to drop into obscurity. Some were limited to a single culture or nation. The 48 traditional Western constellations are Greek. They are given in Aratus' work ''Phenomena'' and Ptolemy's ''Almagest'', though their origin probably predates these works by several centuries. Constellations in the far southern sky were ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boötes
Boötes ( ) is a constellation in the northern sky, located between 0° and +60° declination, and 13 and 16 hours of right ascension on the celestial sphere. The name comes from la, Boōtēs, which comes from grc-gre, Βοώτης, Boṓtēs ' herdsman' or ' plowman' (literally, ' ox-driver'; from ''boûs'' ' cow'). One of the 48 constellations described by the 2nd-century astronomer Ptolemy, Boötes is now one of the 88 modern constellations. It contains the fourth-brightest star in the night sky, the orange giant Arcturus. Epsilon Boötis, or Izar, is a colourful multiple star popular with amateur astronomers. Boötes is home to many other bright stars, including eight above the fourth magnitude and an additional 21 above the fifth magnitude, making a total of 29 stars easily visible to the naked eye. History and mythology In ancient Babylon, the stars of Boötes were known as SHU.PA. They were apparently depicted as the god Enlil, who was the leader of the Baby ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nu1 Boötis
Nu1 Boötis (ν1 Boötis) is an orange-hued star in the northern constellation of Boötes. It has an apparent visual magnitude of +5.02, which indicates the star is faintly visible to the naked eye. Based upon an annual parallax shift of 3.89 mas as seen from Earth, it is located roughly 840 light years distant from the Sun. At that distance, the visual magnitude of the star is diminished by an extinction of 0.13 due to interstellar dust. This is an evolved K-type giant star with a stellar classification of . The 'Ba0.4' suffix notation indicates this is a barium star, which means that the stellar atmosphere has been enhanced by s-process elements most likely provided by what is now an orbiting white dwarf companion. The giant component has times the radius of the Sun. It is radiating 1,626 times the Sun's luminosity from its enlarged photosphere at an effective temperature The effective temperature of a body such as a star or planet is the temperature of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nu2 Boötis
Nu2 Boötis is a white-hued binary star system in the northern constellation of Boötes. It is faintly visible to the naked eye with a combined apparent visual magnitude of 5.02. Based upon an annual parallax shift of 7.86 mas as seen from the Earth, it is located roughly 415 light years from the Sun. The system is moving closer to the Sun with a radial velocity of −16.6 km/s. This stellar pair have a nearly circular orbit with a period of nine years and a semimajor axis of 0.0615 arc seconds. They are both of visual magnitude 5.80 and display a similar spectrum, with the primary, component A, being an A-type main sequence star with a stellar classification of A5 V. This has been identified as an A-type shell star, suggesting there is a circumstellar disk of gas orbiting one or both stars. There are two other stars that appear close to the pair, termed C and D, but they are physically unrelated. Ptolemy considered Nu2 Boötis to be sha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visual Magnitude
Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's light caused by interstellar dust along the line of sight to the observer. The word ''magnitude'' in astronomy, unless stated otherwise, usually refers to a celestial object's apparent magnitude. The magnitude scale dates back to the ancient Roman astronomer Claudius Ptolemy, whose star catalog listed stars from 1st magnitude (brightest) to 6th magnitude (dimmest). The modern scale was mathematically defined in a way to closely match this historical system. The scale is reverse logarithmic: the brighter an object is, the lower its magnitude number. A difference of 1.0 in magnitude corresponds to a brightness ratio of \sqrt /math>, or about 2.512. For example, a star of magnitude 2.0 is 2.512 times as bright as a star of magnitude 3.0, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Main Sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell. Stars on this band are known as main-sequence stars or dwarf stars. These are the most numerous true stars in the universe and include the Sun. After condensation and ignition of a star, it generates thermal energy in its dense core region through nuclear fusion of hydrogen into helium. During this stage of the star's lifetime, it is located on the main sequence at a position determined primarily by its mass but also based on its chemical composition and age. The cores of main-sequence stars are in hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers. The strong dependence of the rate of energy ge ... [...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] |
Heavenly Market Enclosure
The Heavenly Market Enclosure (天市垣, ''Tian Shi Yuan''), is one of the ''San Yuan'' or Three enclosures. Stars and constellations of this group are visible during late summer and early autumn in the Northern Hemisphere (late winter and early spring in the Southern). The Summer Triangle lies directly to the northeast. Asterisms The asterisms are : See also * Twenty-eight mansions * Summer Triangle The Summer Triangle is an astronomical asterism in the northern celestial hemisphere. The defining vertices of this imaginary triangle are at Altair, Deneb, and Vega, each of which is the brightest star of its constellation (Aquila, Cygnus, ... Chinese constellations {{china-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ptolemy
Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of importance to later Byzantine, Islamic, and Western European science. The first is the astronomical treatise now known as the ''Almagest'', although it was originally entitled the ''Mathēmatikē Syntaxis'' or ''Mathematical Treatise'', and later known as ''The Greatest Treatise''. The second is the ''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 natural philosophy of his day. This is sometimes known as the ''Apotelesmatika'' (lit. "On the Effects") but more commonly known as the '' Tetrábiblos'', from the Koine Greek meaning "Four Books", or by its Latin equivalent ''Qua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
