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Theta Aquilae
Theta Aquilae (θ Aql, θ Aquilae) is a binary star in the constellation Aquila. The combined apparent visual magnitude of the pair is 3.26, making it the fourth-brightest member of the constellation. In Chinese, it has the traditional name Tseen Foo , from the Chinese 天 桴 (Mandarin pronunciation ''tiānfú''), which could mean "heavenly raft" or "heavenly ridgepole"; it might also mean "heavenly drumsticks", with Altair, Beta Aquilae and Gamma Aquilae being the drum. This distance to this star can be determined through the parallax technique, yielding an estimate of roughly from Earth. Properties Theta Aquilae is a double-lined spectroscopic binary, which indicates that the individual components have not been viewed through a telescope; instead, what can be viewed is their combined spectrum with the individual absorption line features shifting back and forth over the course of an orbit because of the Doppler effect. Their orbit has a period of 17.1 days with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquila (constellation)
Aquila is a constellation on the celestial equator. Its name is Latin for 'eagle' and it represents the bird that carried Zeus/Jupiter's thunderbolts in Greek-Roman mythology. Its brightest star, Altair, is one vertex of the Summer Triangle asterism. The constellation is best seen in the northern summer, as it is located along the Milky Way. Because of this location, many clusters and nebulae are found within its borders, but they are dim and galaxies are few. History Aquila was one of the 48 constellations described by the second-century astronomer Ptolemy. It had been earlier mentioned by Eudoxus in the fourth century BC and Aratus in the third century BC. It is now one of the 88 constellations defined by the International Astronomical Union. The constellation was also known as ''Vultur volans'' (the flying vulture) to the Romans, not to be confused with ''Vultur cadens'' which was their name for Lyra. It is often held to represent the eagle which held Zeus's/Jupiter's t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angular Separation
Angular distance \theta (also known as angular separation, apparent distance, or apparent separation) is the angle between the two sightlines, or between two point objects as viewed from an observer. Angular distance appears in mathematics (in particular geometry and trigonometry) and all natural sciences (e.g. astronomy and geophysics). In the classical mechanics of rotating objects, it appears alongside angular velocity, angular acceleration, angular momentum, moment of inertia and torque. Use The term ''angular distance'' (or ''separation'') is technically synonymous with ''angle'' itself, but is meant to suggest the linear distance between objects (for instance, a couple of stars observed from Earth). Measurement Since the angular distance (or separation) is conceptually identical to an angle, it is measured in the same units, such as degrees or radians, using instruments such as goniometers or optical instruments specially designed to point in well-defined directions and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Al Achsasi Al Mouakket
Muḥammad al-Akhṣāṣī al-Muwaqqit ( ar, محمد الاخصاصي الموقت) was an Egyptian astronomer whose and catalogue of stars, ('Pearls of brilliance upon the solar operations'), was written at Cairo about 1650. Al-Akhsasi was a shaykh, a learned elder, of the Grand Mosque of the university of Cairo, where his name ''al- Muwaqqit'' reflected his position regulating the times and hours at the mosque. His name Akhsasi connects him in origin to a village in the Faiyum, southwest of Cairo. No copies of his book were known to Western astronomers or historians of science The history of science covers the development of science from ancient times to the present. It encompasses all three major branches of science: natural, social, and formal. Science's earliest roots can be traced to Ancient Egypt and Mesop ... until 1895;Knobel 1895. thus he did not appear in the standard French and English bibliographies and library catalogues of the 19th century. Notes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chinese Star Names
Chinese star names (Chinese: , ''xīng míng'') are named according to ancient Chinese astronomy and astrology. The sky is divided into star mansions (, ''xīng xiù'', also translated as "lodges") and asterisms (, ''xīng guān''). The system of 283 asterisms under Three Enclosures and Twenty-eight Mansions was established by Chen Zhuo of the Three Kingdoms period, who synthesized ancient constellations and the asterisms created by early astronomers Shi Shen, Gan De and Wuxian. Since the Han and Jin Dynasties, stars have been given reference numbers within their asterisms in a system similar to the Bayer or Flamsteed designations, so that individual stars can be identified. For example, Deneb (α Cyg) is referred to as (''Tiān Jīn Sì'', the Fourth Star of Celestial Ford). In the Qing Dynasty, Chinese knowledge of the sky was improved by the arrival of European star charts. ''Yixiang Kaocheng'', compiled in mid-18th century by then deputy Minister of Rites Ignaz Kögler, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eta Aquilae
Eta Aquilae (η Aql, η Aquilae) is the Bayer designation for a multiple star in the equatorial constellation of Aquila, the eagle. It was once part of the former constellation Antinous. On average, this star has an apparent visual magnitude of 3.87, making it one of the brighter members of Aquila. Based upon parallax measurements made during the Hipparcos mission, this star is located at a distance of roughly , although the parallax estimate has a 44% margin of error. System The η Aquilae system contains at least two stars, probably three. The primary star η Aql A is by far the brightest and dominates the spectrum. An ultraviolet excess in the spectral energy distribution suggest the presence of a faint hot companion, η Aql B, which has been given a spectral type of B8.9 V. The fractional spectral type is an artefact of the mathematics used to model the spectrum, not an indication of any specific spectral features that would be intermediate between B8 and B9. Radial ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
58 Aquilae
58 Aquilae is a single star located around 520 light years from the Sun in the celestial equator, equatorial constellation of Aquila (constellation), Aquila, near Eta Aquilae. ''58 Aquilae'' is its Flamsteed designation. It is visible to the naked eye as a dim, blue-white hued star with an apparent visual magnitude of 5.60. This object is moving closer to the Earth with a heliocentric radial velocity of −53 km/s, and may come as close as in around 1.8 million years. This object has a stellar classification of B9 IV, matching a late star, late B-type star, B-type subgiant star. It has 5.6 times the radius of the Sun with a high rate of spin, showing a projected rotational velocity of 110 km/s. The star is radiating 117 times the luminosity of the Sun from its photosphere at an effective temperature of 7,946 K. References {{DEFAULTSORT:58 Aquilae B-type subgiants Aquila (constellation) Durchmusterung objects Flamsteed objects, Aquilae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
62 Aquilae
62 Aquilae is a single star located about 427 light years away from the Sun in the equatorial constellation of Aquila. ''62 Aquilae'' is its Flamsteed designation. It is visible to the naked eye as a dim, orange-hued star with an apparent visual magnitude of 5.67. This is an aging giant star with a stellar classification of K4 III, having exhausted the supply of hydrogen at its core and expanded to 23 times the girth of the Sun. It is 11.2 billion years old with 0.89 times the Sun's mass. The star is radiating 153 times the luminosity of the Sun from its swollen photosphere at an 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 ... of 4,246 K. References {{DEFAULTSORT:62 Aquilae K-type giants Aquila (constellation) Durchmuste ... [...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] |
Subgiant Star
A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution of a star. Yerkes luminosity class IV The term subgiant was first used in 1930 for class G and early K stars with absolute magnitudes between +2.5 and +4. These were noted as being part of a continuum of stars between obvious main-sequence stars such as the Sun and obvious giant stars such as Aldebaran, although less numerous than either the main sequence or the giant stars. The Yerkes spectral classification system is a two-dimensional scheme that uses a letter and number combination to denote that temperature of a star (e.g. A5 or M1) and a Roman numeral to indicate the luminosity relative to other stars of the same temperature. Luminosity class IV stars are the subgiants, located between main-sequence stars (luminosity class V) ... [...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] |
Giant Star
A giant star is a star with substantially larger radius and luminosity than a main sequence, main-sequence (or ''dwarf'') star of the same effective temperature, surface temperature.Giant star, entry in ''Astronomy Encyclopedia'', ed. Patrick Moore, New York: Oxford University Press, 2002. . They lie above the main sequence (luminosity class V in the Spectral classification#Yerkes spectral classification, Yerkes spectral classification) on the Hertzsprung–Russell diagram and correspond to luminosity classes II and III.giant, entry in ''The Facts on File Dictionary of Astronomy'', ed. John Daintith and William Gould, New York: Facts On File, Inc., 5th ed., 2006. . The terms ''giant'' and ''dwarf'' were coined for stars of quite different luminosity despite similar temperature or spectral type by Ejnar Hertzsprung about 1905. Giant stars have radii up to a few hundred times the solar radii, Sun and luminosities between 10 and a few thousand times that of the Sun. Stars still mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
