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List Of Stars In Ursa Major ...
This is the list of notable stars in the constellation Ursa Major, sorted by decreasing brightness. See also *List of stars by constellation References * * * * {{Lists of stars by constellation *List Ursa Major Ursa Major (; also known as the Great Bear) is a constellation in the northern sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) bear," referring to and contrasting it with nearby Ursa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Star
A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sky, night, but their immense distances from Earth make them appear as fixed stars, fixed points of light. The most prominent stars have been categorised into constellations and asterism (astronomy), asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated to stars. Only about 4,000 of these stars are visible to the naked eye, all within the Milky Way galaxy. A star's life star formation, begins with the gravitational collapse of a gaseous nebula of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. Its stellar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brown Dwarf
Brown dwarfs (also called failed stars) are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen ( 1H) into helium in their cores, unlike a main-sequence star. Instead, they have a mass between the most massive gas giant planets and the least massive stars, approximately 13 to 80 times that of Jupiter (). However, they can fuse deuterium ( 2H), and the most massive ones (> ) can fuse lithium ( 7Li). Astronomers classify self-luminous objects by spectral class, a distinction intimately tied to the surface temperature, and brown dwarfs occupy types M, L, T, and Y. As brown dwarfs do not undergo stable hydrogen fusion, they cool down over time, progressively passing through later spectral types as they age. Despite their name, to the naked eye, brown dwarfs would appear in different colors depending on their temperature. The warmest ones are possibly orange or red, while cooler brown dwarfs would likely appear magenta or black to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delta Ursae Majoris
Delta Ursae Majoris (δ Ursae Majoris, abbreviated Delta UMa, δ UMa), formally named Megrez , is a star in the northern constellation of Ursa Major. With an apparent magnitude of +3.3, it is the dimmest of the seven stars in the Big Dipper asterism. Parallax measurements yield a distance estimate of from the Sun. Stellar properties Delta Ursae Majoris has 63% more mass than the Sun and is about 1.4 times its radius. It has a stellar classification of A3 V, which means it is an A-type main sequence star that is generating energy at its core through the nuclear fusion of hydrogen. It shines at 14 times the luminosity of the Sun, with this energy being emitted from its outer envelope at an effective temperature of 9,480 K. This gives it the white hue typical of an A-type star. This star has an excess emission of infrared radiation, indicating the presence of circumstellar matter. This forms a debris disk around an orbital radius of 16 ast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iota Ursae Majoris
Iota Ursae Majoris (ι Ursae Majoris, abbreviated Iota UMa, ι UMa), also named Talitha , is a star system in the northern circumpolar constellation of Ursa Major. It has an apparent visual magnitude of 3.14, making it visible to the naked eye and placing it among the brighter members of this constellation. Based upon parallax measurements, it is located at a distance of from the Sun. Nomenclature ''ι Ursae Majoris'' ( Latinised to ''Iota Ursae Majoris'') is the star's Bayer designation. The traditional name ''Talitha'', (which was shared with Kappa Ursae Majoris) comes from the Arabic phrase ( ar, الفقرة الثالثة), a mis-transcription of ( ar, القفزة الثالثة), which means "the third spring, or leap, of the ghazal". The term ''Borealis'' meaning "the north side" in Latin. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theta Ursae Majoris
Theta Ursae Majoris (Theta UMa, θ Ursae Majoris, θ UMa) is a suspected spectroscopic binary star system in the northern circumpolar constellation of Ursa Major. It has an apparent visual magnitude of 3.17, placing it among the brighter members of this constellation. The distance to this star has been measured directly using the parallax method, yielding an estimated value of . In 1976, this was reported as a spectroscopic binary system by Helmut A. Abt and Saul G. Levy, giving it an orbital period of 371 days. However, this was brought into question by Christopher L. Morbey and Roger F. Griffin in 1987, who suggested that the data could be explained by random chance. Further observations in 2009 with observations with the Bok Telescope in Arizona did show changes of 180 m/s in radial velocity, although there was not sufficient evidence to support a Keplerian orbit Johannes Kepler (; ; 27 December 1571 – 15 November 1630) was a German ast ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semiregular Variable
In astronomy, a semiregular variable star, a type of variable star, is a giant or supergiant of intermediate and late (cooler) spectral type showing considerable periodicity in its light changes, accompanied or sometimes interrupted by various irregularities. Periods lie in the range from 20 to more than 2000 days, while the shapes of the light curves may be rather different and variable with each cycle. The amplitudes may be from several hundredths to several magnitudes (usually 1-2 magnitudes in the V filter). Classification The semiregular variable stars have been sub-divided into four categories for many decades, with a fifth related group defined more recently. The original definitions of the four main groups were formalised in 1958 at the tenth general assembly of the International Astronomical Union (IAU). The General Catalogue of Variable Stars (GCVS) has updated the definitions with some additional information and provided newer reference stars where old examples such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mu Ursae Majoris
Mu Ursae Majoris (μ Ursae Majoris, abbreviated Mu UMa, μ UMa), formally named Tania Australis , is a binary star in the constellation of Ursa Major. An apparent visual magnitude of +3.06 places it among the brighter members of the constellation. Parallax measurements give an estimated distance of roughly from the Sun, with a margin of error of 4%. Stellar system Mu Ursae Majoris is an evolved star that is currently in the red giant stage with a stellar classification of M0 IIIab. It has expanded to 75 times the radius of the Sun whilst the outer atmosphere has cooled to an effective temperature of 3,899 K, giving it the orange-red hued glow of an M-type star. Estimates of the luminosity range from 977–1,200 times that of the Sun. It is classified as a suspected variable star with a brightness variation from magnitude 2.99m to 3.33m. This is a spectroscopic binary star system with a companion a mere 0.2 AU from the primary, assuming a dist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psi Ursae Majoris
Psi Ursae Majoris (Psi UMa, ψ Ursae Majoris, ψ UMa) is a star in the northern circumpolar constellation of Ursa Major. It has an apparent visual magnitude of +3.01, making it a third magnitude star and one of the brighter members of the constellation. Parallax measurements place it at a distance of from Earth. This is sufficiently close that the magnitude of the star is only reduced by 0.05 due to extinction. In Chinese astronomy, Psi Ursae Majoris is called Tien Tsan or Ta Tsun, "Extremely Honorable". The name was possibly derived from the word 太尊, Pinyin: Tàizūn, meaning ''Royals'', because this star stands alone as the only member of the ''Royals'' asterism within the Purple Forbidden enclosure (see Chinese constellation). The spectrum of this star matches a stellar classification of K1 III, with the luminosity class of 'III' indicating this is an evolved giant star that has exhausted the supply of hydrogen at its core. As a consequence, i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Ursae Majoris
Gamma Ursae Majoris (γ Ursae Majoris, abbreviated Gamma UMa, γ UMa), formally named Phecda , is a star in the constellation of Ursa Major. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. Based upon parallax measurements with the ''Hipparcos'' astrometry satellite, it is located at distance of around from the Sun. It is more familiar to most observers in the northern hemisphere as the lower-left star forming the bowl of the Big Dipper, together with Alpha Ursae Majoris (Dubhe, upper-right), Beta Ursae Majoris (Merak, lower-right) and Delta Ursae Majoris (Megrez, upper-left). Along with four other stars in this well-known asterism, Phecda forms a loose association of stars known as the Ursa Major moving group. Like the other stars in the group, it is a main sequence star, as the Sun is, although somewhat hotter, brighter and larger. Phecda is located in relatively close physical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Ursae Majoris
Beta Ursae Majoris (β Ursae Majoris, abbreviated Beta UMa, β UMa), formally named Merak , is a star in the northern constellation of Ursa Major. The apparent visual magnitude of this star is +2.37, which means it is readily visible to the naked eye. It is more familiar to northern hemisphere observers as one of the "pointer stars" in the Big Dipper, or the Plough (UK), which is a prominent asterism of seven stars that forms part of the larger constellation. Extending an imaginary straight line from this star through the nearby Alpha Ursae Majoris (Dubhe) extends to Polaris, the north star. Spectral classification In 1943, β Ursae Majoris was listed as a spectral standard for the class of A1 V. When improved instruments made it possible to identify subgiant luminosity classes for early A-class stars, β Ursae Majoris was assigned that class A0 IV. This was later revised to A1 IV. It is considered to be a mild Am star, a type of chemically ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectroscopic Binary
A binary star is a system of two star, stars that are gravity, gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in which case they are called ''visual binaries''. Many visual binaries have long orbital periods of several centuries or millennia and therefore have orbits which are uncertain or poorly known. They may also be detected by indirect techniques, such as spectroscopy (''spectroscopic binaries'') or astrometry (''astrometric binaries''). If a binary star happens to orbit in a plane along our line of sight, its components will eclipse and transit (astronomy), transit each other; these pairs are called ''eclipsing binaries'', or, together with other binaries that change brightness as they orbit, ''photometric binaries''. If components in binary star systems are close enough they can gravitationally distort their mutual outer stella ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mizar
Mizar is a second-magnitude star in the handle of the Big Dipper asterism in the constellation of Ursa Major. It has the Bayer designation ζ Ursae Majoris ( Latinised as Zeta Ursae Majoris). It forms a well-known naked eye double star with the fainter star Alcor, and is itself a quadruple star system. The Mizar and Alcor system lies about 83 light-years away from the Sun, as measured by the Hipparcos astrometry satellite, and is part of the Ursa Major Moving Group. Nomenclature ''ζ Ursae Majoris'' ( Latinised to ''Zeta Ursae Majoris'' and abbreviated to ζ UMa or Zeta UMa) is Mizar's Bayer designation. It also has the Flamsteed designation 79 Ursae Majoris. The traditional name ''Mizar'' derives from the Arabic ' ' meaning 'apron; wrapper, covering, cover'. 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
