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Iota Aquilae
Iota Aquilae, Latinized from ι Aquilae, is the Bayer designation for a star in the equatorial constellation of Aquila. It has the traditional name Al Thalimain , which it shares with λ Aquilae. The name is derived from the Arabic term الظليمین ''al-ẓalīmayn'' meaning "The Two Ostriches". With an apparent visual magnitude of 4.364, this star is bright enough to be seen with the naked eye. Based upon an annual parallax shift of , it is located at a distance of around from Earth. At that distance, the visual magnitude of the star is diminished by 0.15 from extinction caused by intervening gas and dust. Although Iota Aquilae is listed in star catalogues as a giant star, calculations of its dimension show that in reality it is a main-sequence star. It has nearly five times the mass of the Sun and five to six times the Sun's radius. It is emitting 851 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 14,552 K, givin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquila IAU
Aquila may refer to: Arts, entertainment, and media * ''Aquila'', a series of books by S.P. Somtow * ''Aquila'', a 1997 book by Andrew Norriss * ''Aquila'' (children's magazine), a UK-based children's magazine * ''Aquila'' (journal), an ornithological journal * ''Aquila'' (TV series), a BBC TV production for children based on the Norriss book * Aquila Theatre, a theatre company of New York Fictional entities * ''Aquila'', a ship in the video game '' Star Ocean: The Last Hope'' * ''Aquila'', a ship in the video game ''Assassin's Creed III'' * Aquila Yuna, a character in the anime ''Saint Seiya Omega'' * Aquila, a medieval city in the fantasy film '' Ladyhawke'' (1985) People * Aquila (name), a given name or surname Places * Aquila, Michoacán, a town in Mexico * Aquila, Switzerland, a former municipality * Aquila, Veracruz, a municipality in Mexico * L'Aquila, sometimes Aquila, the regional capital of Abruzzo in Italy * Province of L'Aquila, Italy Transportation Automoti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects show a larger parallax than farther objects when observed from different positions, so parallax can be used to determine distances. To measure large distances, such as the distance of a planet or a star from Earth, astronomers use the principle of parallax. Here, the term ''parallax'' is the semi-angle of inclination between two sight-lines to the star, as observed when Earth is on opposite sides of the Sun in its orbit. These distances form the lowest rung of what is called "the cosmic distance ladder", the first in a succession of methods by which astronomers determine the distances to celestial objects, serving as a basis for other distance measurements in astronomy forming the higher rungs of the ladder. Parallax also affects optical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delta Aquilae
Delta Aquilae, Latinized from δ Aquilae, is a binary star system in the equatorial constellation of Aquila. It has an apparent visual magnitude of 3.4 and, based upon parallax measurements, is located at a distance of about from Earth. It is drifting closer with a radial velocity of −30 km/s. The system is predicted to come to within of the Sun in around 335,000 years. Properties The binary nature of this system was first reported by H. L. Alden at Yale Observatory in 1936. It is an astrometric binary where the two components orbit each other with a period of 3.422 years and an eccentricity (ovalness) of about 0.36. This is a type of binary star system where the presence of the secondary component is revealed by its gravitational perturbation of the primary. The individual components have not been resolved with a telescope. The primary member, designated component Aa, is an aging subgiant star with a stellar classification of F0 IV, where the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sigma Aquilae
Sigma Aquilae, Latinized from σ Aquilae, is the Bayer designation for a binary star system in the equatorial constellation of Aquila. The baseline apparent magnitude of the pair is +5.17, which, according to the Bortle Dark-Sky Scale, is bright enough to be seen with the naked eye from suburban skies. Because of the Earth's orbit about the Sun, this system has an annual parallax shift of . This provides a distance estimate of approximately . Sigma Aquilae is a double-lined spectroscopic binary system consisting of two massive B-type main sequence stars; each has a stellar classification of B3 V. They are detached components, which means the two stars are sufficiently distant from each other that neither fills its Roche lobe. Because the orbital plane lies close to the line of sight with the Earth, they form an eclipsing binary system. The two components are each distorted by the gravity of the other star, and their shapes mean that the magnitude of the star ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mu Aquilae
Mu Aquilae, Latinized from μ Aquilae, is the Bayer designation for a single star in the equatorial constellation of Aquila. With an apparent visual magnitude of 4.45, it is visible to the naked eye. The measured annual parallax shift of this star is , which gives a distance estimate of from Earth. It is drifting closer with a radial velocity of −25 km/s, and displays a relatively high proper motion, traversing the celestial sphere at the rate of per year. The stellar classification of Mu Aquilae is K3-IIIb Fe0.5, indicating that this is an evolved giant star with a mild overabundance of iron appearing in its spectrum. It belongs to a sub-category of giants called the red clump, which means it is generating energy through the fusion of helium at its core. Compared to the Sun, it has 116% of the mass and has expanded to 7.7 times the size. This inflated outer envelope has an effective temperature The effective temperature of a body such as a star or pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ox (Chinese Constellation)
The Ox mansion (牛宿, pinyin: Niú Xiù) is one of the Twenty-eight mansions of the Chinese constellations. It is one of the northern mansions of the Black Tortoise. The primary asterism of this mansion is centered on the tail of the constellation known as Capricornus Capricornus is one of the constellations of the zodiac. Its name is Latin for "horned goat" or "goat horn" or "having horns like a goat's", and it is commonly represented in the form of a sea goat: a mythical creature that is half goat, half f ... in Western astronomy. Asterisms References {{DEFAULTSORT:Ox (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 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] |
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 surface. The rotation of a star produces an equatorial bulge due to centrifugal force. As stars are not solid bodies, they can also undergo differential rotation. Thus the equator of the star can rotate at a different angular velocity than the higher latitudes. These differences in the rate of rotation within a star may have a significant role in the generation of a stellar magnetic field. The magnetic field of a star interacts with the stellar wind. As the wind moves away from the star its rate of angular velocity slows. The magnetic field of the star interacts with the wind, which applies a drag to the stellar rotation. As a result, angular momentum is transferred from the star to the wind, and over time this gradually slows the star's rate of rotation. Measurement Unless a star is being obse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
B-type Star
A B-type main-sequence star (B V) is a main-sequence (hydrogen-burning) star of spectral type B and luminosity class V. These stars have from 2 to 16 times the mass of the Sun and surface temperatures between 10,000 and 30,000 K. B-type stars are extremely luminous and blue. Their spectra have neutral helium, which are most prominent at the B2 subclass, and moderate hydrogen lines. Examples include Regulus and Algol A. This class of stars was introduced with the Harvard sequence of stellar spectra and published in the ''Revised Harvard photometry'' catalogue. The definition of type B-type stars was the presence of non-ionized helium lines with the absence of singly ionized helium in the blue-violet portion of the spectrum. All of the spectral classes, including the B type, were subdivided with a numerical suffix that indicated the degree to which they approached the next classification. Thus B2 is 1/5 of the way from type B (or B0) to type A. Later, however, more refined s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 when the body's emissivity curve (as a function of wavelength) is not known. When the star's or planet's net emissivity in the relevant wavelength band is less than unity (less than that of a black body), the actual temperature of the body will be higher than the effective temperature. The net emissivity may be low due to surface or atmospheric properties, including greenhouse effect. Star The effective temperature of a star is the temperature of a black body with the same luminosity per ''surface area'' () as the star and is defined according to the Stefan–Boltzmann law . Notice that the total (bolometric) luminosity of a star is then , where is the stellar radius. The definition of the stellar radius is obviously not straightf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Atmosphere
The stellar atmosphere is the outer region of the volume of a star, lying above the stellar core, radiation zone and convection zone. Overview The stellar atmosphere is divided into several regions of distinct character: * The photosphere, which is the atmosphere's lowest and coolest layer, is normally its only visible part. Light escaping from the surface of the star stems from this region and passes through the higher layers. The Sun's photosphere has a temperature in the 5,770 K to 5,780 K range. Starspots, cool regions of disrupted magnetic field lie on the photosphere. * Above the photosphere lies the chromosphere. This part of the atmosphere first cools down and then starts to heat up to about 10 times the temperature of the photosphere. * Above the chromosphere lies the transition region, where the temperature increases rapidly on a distance of only around 100 km. * The outermost part of the stellar atmosphere is the corona, a tenuous plasma which has a tem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Main-sequence Star
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 gene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
