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Eta Aquilae
Eta Aquilae is a multiple star system in the equatorial constellation of Aquila, the eagle. Its name is a Bayer designation that is Latinized from η Aquilae, and abbreviated Eta Aql or η Aql. This star was once part of the former constellation Antinous. Its apparent visual magnitude varies between 3.49 and 4.3, making it one of the brighter members of Aquila. Based upon parallax measurements made by the Gaia spacecraft on its third data release ( DR3), this star is located at a distance of approximately . The primary component is a Classical Cepheid variable. 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 fitted to a spectral type of B8.9 V. The fractional spectral type is an artefact of the mathematics used to model the spectrum, not an ... [...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 Greco-Roman mythology, Greek-Roman mythology. Its brightest star, Altair, is one vertex of the Summer Triangle asterism (astronomy), 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 planetary nebula, 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 of Cnidus, 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 Ancient Rome, Romans, not to be confused with ''Vultur cadens'' which wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Period
The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets, exoplanets orbiting other stars, or binary stars. It may also refer to the time it takes a satellite orbiting a planet or moon to complete one orbit. For celestial objects in general, the orbital period is determined by a 360° revolution of one body around its primary, ''e.g.'' Earth around the Sun. Periods in astronomy are expressed in units of time, usually hours, days, or years. Its reciprocal is the orbital frequency, a kind of revolution frequency, in units of hertz. Small body orbiting a central body According to Kepler's Third Law, the orbital period ''T'' of two point masses orbiting each other in a circular or elliptic orbit is: :T = 2\pi\sqrt where: * ''a'' is the orbit's semi-major axis * ''G'' is the gravitationa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Doradus
Beta Doradus, Latinized from β Doradus, is the second brightest star in the southern constellation of Dorado. It is a Classical Cepheid variable, with an apparent magnitude that varies between 3.46 and 4.08. Based upon parallax measurements with the Hubble Space Telescope, it is located at a distance of from Earth. Characteristics Beta Doradus is a Cepheid variable that regularly changes magnitude from a low of 4.08 to a high of 3.46 over a period of 9.84318 days. The light curve of this magnitude change follows a nearly regular saw-tooth pattern, with average amplitude variations period to period about 0.005 magnitude from average amplitude of 0.62 magnitude. During each radial pulsation cycle, the radius of the star varies by around a mean of . Its spectral type and luminosity class are likewise variable, from F-type to G-type and from a supergiant to a bright giant. Far ultraviolet emissions have been detected from this star with the Far Ultraviolet Spectro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zeta Geminorum
Zeta Geminorum (ζ Geminorum, abbreviated Zeta Gem, ζ Gem) is a Bright Star Catalogue, bright star with cluster components, distant optical binary, optical components and a likely spectroscopic binaries, spectroscopic partner in the zodiac constellation of Gemini (constellation), Gemini — in its south, on the left 'leg' of the twin Pollux (star), Pollux. It is a classical Cepheid variable, classical Cepheid variable star, of which over 800 have been found in our galaxy. As such its regular pulsation and luminosity (proven in its class to correspond) and its relative proximity means the star is a useful calibrator star, calibrator in computing the cosmic distance ladder. Based on stellar parallax, parallax measurements, it is approximately 1,200 light-years from the Sun. Zeta Geminorum is the primary or 'A' component of a multiple star system designated WDS J07041+2034. It bears traditional name Mekbuda, usually anglicised to . Nomenclature ''ζ Geminorum'' (Latinisati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delta Cephei
Delta Cephei (δ Cep, δ Cephei) is a quadruple star system located approximately 887 light-years away in the northern constellation of Cepheus (constellation), Cepheus, the King. At this distance, the visual magnitude of the star is diminished by 0.23 as a result of extinction (astronomy), extinction caused by gas and dust along the line of sight. It is the prototype of the Cepheid variable stars that undergo periodic changes in luminosity. Discovery Delta Cephei was discovered to be variable by John Goodricke during 1784. He describes his first observation on October 19, 1784, followed by a regular series of observations most nights until December 28. Further observations were made during the first half of 1785, the variability was described in a letter dated June 28, 1785, and formally published on January 1, 1786. This was the second variable star of this type, with Eta Aquilae being discovered just a few weeks earlier, on September 10, 1784. Properties As well as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apparent Magnitude
Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), extinction of the object's light caused by interstellar dust along the sightline, line of sight to the observer. Unless stated otherwise, the word ''magnitude'' in astronomy usually refers to a celestial object's apparent magnitude. The magnitude scale likely dates to before the ancient Ancient Greek astronomy#Astronomy in the Greco-Roman and Late Antique eras, Roman astronomer Ptolemy, Claudius Ptolemy, whose Star catalogue, star catalog popularized the system by listing stars from First-magnitude star, 1st magnitude (brightest) to 6th magnitude (dimmest). The modern scale was mathematically defined to closely match this historical system by Norman Robert Pogson, Norman Pogson in 1856. The scale is reverse logarithmic scale, logarithmic: ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edward Pigott
Edward Pigott (1753–1825) was an English astronomer notable for being one of the founders of the study of variable stars. Biography Son of the astronomer Nathaniel Pigott, Pigott's work focused on variable stars. Educated in France with a mother from Louvain, the family moved to York in 1781. Despite their significant age difference, he was a friend and collaborator of John Goodricke (his distant cousin) until the latter's untimely death at the age of 21 in 1786. In 1784, Pigott informed the Royal Society of his discovery of a new variable star. This was Eta Aquilae which he had identified the previous year. He corresponded with leading astronomers of the day including William Herschel and Nevil Maskelyne. Pigott moved to Bath in 1796. Pigott's notebooks survive aYork City Archives Honors Asteroid 10220 Pigott is named after Edward and his father. It was discovered by R. A. Tucker at the observatory in Tucson, Arizona Tucson (; ; ) is a city in Pima County ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Classical Cepheids
Classical Cepheids are a type of Cepheid variable star. They are young, population I variable stars that exhibit regular radial Stellar pulsation, pulsations with periods of a few days to a few weeks and visual amplitudes ranging from a few tenths of a Magnitude (astronomy), magnitude up to about 2 magnitudes. Classical Cepheids are also known as Population I Cepheids, Type I Cepheids, and Delta Cepheid variables. There exists a well-defined Period-luminosity relation, relationship between a classical Cepheid variable's luminosity and pulsation period, securing Cepheids as viable standard candles for establishing the galactic and extragalactic distance scales. Hubble Space Telescope (HST) observations of classical Cepheid variables have enabled firmer constraints on Hubble's law, which describes the expansion rate of the observable Universe. Classical Cepheids have also been used to clarify many characteristics of our galaxy, such as the local spiral arm structure and the Sun's di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interstellar Dust
Cosmic dustalso called extraterrestrial dust, space dust, or star dustis dust that occurs in outer space or has fallen onto Earth. Most cosmic dust particles measure between a few molecules and , such as micrometeoroids (30 μm). Cosmic dust can be further distinguished by its astronomical location: intergalactic dust, interstellar dust, interplanetary dust (as in the zodiacal cloud), and circumplanetary dust (as in a planetary ring). There are several methods to obtain space dust measurement. In the Solar System, interplanetary dust causes the zodiacal light. Solar System dust includes comet dust, planetary dust (like from Mars), asteroidal dust, dust from the Kuiper belt, and interstellar dust passing through the Solar System. Thousands of tons of cosmic dust are estimated to reach Earth's surface every year, with most grains having a mass between 10−16 kg (0.1 pg) and 10−4 kg (0.1 g). The density of the dust cloud through which the Earth is traveling is approximately ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinction (astronomy)
In astronomy, extinction is the absorption (electromagnetic radiation), absorption and light scattering, scattering of electromagnetic radiation by dust and gas between an emitting astronomical object and the observation, observer. Interstellar extinction was first documented as such in 1930 by Robert Julius Trumpler. However, its effects had been noted in 1847 by Friedrich Georg Wilhelm von Struve, and its effect on the colors of stars had been observed by a number of individuals who did not connect it with the general presence of Cosmic dust, galactic dust. For stars lying near the plane of the Milky Way which are within a few thousand parsecs of the Earth, extinction in the visual band of frequencies (photometric system) is roughly 1.8 Magnitude (astronomy), magnitudes per kiloparsec. For Observatory#Ground-based_observatories, Earth-bound observers, extinction arises both from the interstellar medium and the Atmosphere of Earth, Earth's atmosphere; it may also arise fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnitude (astronomy)
In astronomy, magnitude is a measure of the brightness of an astronomical object, object, usually in a defined passband. An imprecise but systematic determination of the magnitude of objects was introduced in ancient times by Hipparchus. Magnitude values do not have a unit. The scale is Logarithmic scale, logarithmic and defined such that a magnitude 1 star is exactly 100 times brighter than a magnitude 6 star. Thus each step of one magnitude is \sqrt[5] \approx 2.512 times brighter than the magnitude 1 higher. The brighter an object appears, the lower the value of its magnitude, with the brightest objects reaching negative values. Astronomers use two different definitions of magnitude: apparent magnitude and absolute magnitude. The ''apparent'' magnitude () is the brightness of an object and depends on an object's intrinsic luminosity, its Cosmic distance ladder, distance, and the Extinction (astronomy), extinction reducing its brightness. The ''absolute'' magnitude () describes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
