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23 Ophiuchi
This is the list of notable stars in the constellation Ophiuchus, sorted by decreasing brightness. See also *List of stars by constellation All stars but one can be associated with an IAU constellation. IAU constellations are areas of the sky. Although there are only 88 IAU constellations, the sky is actually divided into 89 irregularly shaped boxes as the constellation Serpens is spli ... References * * * * {{DEFAULTSORT:Stars in Ophiuchus, List of *List Ophiuchus ... [...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] |
Alpha Ophiuchi
Alpha Ophiuchi (α Ophiuchi, abbreviated Alpha Oph, α Oph), also named Rasalhague , is a binary star and the brightest star in the constellation of Ophiuchus. Nomenclature The name Alpha Ophiuchi is a Romanisation of the star's Bayer designation, ''α Ophiuchi''. It is also known by the traditional name ''Rasalhague'', from the Arabic رأس الحواء ''raʼs al-ḥawwāʼ'' "the head of the serpent collector". 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 included a table of the first two collections of approved names, formally listing Alpha Ophiuchi as ''Rasalhague''. Properties Alpha Ophiuchi is a binary star system with an orbital period of about 8.62 years. The orbital parameters were only poorly known until 2011 when observations using adaptive optics produced a better orbital fit, allowing the individual masses of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
72 Ophiuchi
72 Ophiuchi is a binary star system in the equatorial constellation of Ophiuchus. It is visible to the naked eye as a faint, white-hued point of light with a combined apparent visual magnitude of 3.73. It is located approximately 86.9 light years away from the Sun based on parallax, but is moving closer with a heliocentric radial velocity of -23.9 km/s. As of 2008, the pair had an angular separation of . According to Gray et al. (2003), the primary component has a stellar classification of A5 V, matching an A-type main-sequence star. Cowley et al. (1969) had assigned it to a class of A4 IVs, suggesting it is a sharp- lined (s) subgiant star. The latter class is still in use by some sources. The primary is 250 million years old with double the mass of the Sun and is spinning with a moderate projected rotational velocity of 65 km/s. It is radiating 20 times the luminosity of the Sun from its photosphere at an effective temperature of 8,718& ... [...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] |
Nu Ophiuchi
Nu Ophiuchi (ν Oph, ν Ophiuchi) is a star in the equatorial constellation of Ophiuchus. The apparent visual magnitude is +3.3, making it one of the brighter members of this constellation. Based upon parallax measurements made during the Hipparcos mission, this star is located about from Earth. Properties Nu Ophiuchi has about three times the mass of the Sun and is roughly 330 million years old. The spectrum of the star matches a stellar classification of K0 IIIa, indicating it is a giant star that has exhausted the supply of hydrogen at its core and evolved away from the main sequence of stars. Unusually, it displays an anomalously low abundance of cyanogen for a star of its type. The star's outer envelope has expanded to around 14 times the Sun's radius and now radiates with a luminosity 123 times that of the Sun. This energy is emitted from its outer envelope at an effective temperature of 4,928 K, giving it the cool, orange hue of a K-type star. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Cephei Variable
Beta Cephei variables, also known as Beta Canis Majoris stars, are variable stars that exhibit small rapid variations in their brightness due to pulsations of the stars' surfaces, thought due to the unusual properties of iron at temperatures of 200,000 K in their interiors. These stars are usually hot blue-white stars of spectral class B and should not be confused with Cepheid variables, which are named after Delta Cephei and are luminous supergiant stars. Properties Beta Cephei variables are main-sequence stars of masses between about 7 and 20 M_\odot (that is, 7–20 times as massive as the Sun). Among their number are some of the brightest stars in the sky, such as Beta Crucis and Beta Centauri; Spica is also classified as a Beta Cephei variable but mysteriously stopped pulsating in 1970. Typically, they change in brightness by 0.01 to 0.3 magnitudes with periods of 0.1 to 0.3 days (2.4–7.2 hours). The prototype of these variable stars, Beta Cephei, shows variation in apparen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theta Ophiuchi
Theta Ophiuchi, Latinized from θ Ophiuchi, is a multiple star system in the equatorial constellation of Ophiuchus. It lies on the "right foot" of the serpent-bearer, just southwest of Kepler's Star, the nova of 1604. According to Richard H. Allen's '' Star Names: Their Lore and Meaning'' (1899), θ Oph together with ξ Oph formed the Sogdian ''Wajrik'' "the Magician", the Khorasmian ''Markhashik'' "the Serpent-bitten" and with η Oph the Coptic ''Tshiō'', "the Snake", and ''Aggia'', "the Magician". This star has an apparent visual magnitude of +3.3, making it readily visible to the naked eye. Based upon parallax measurements from the Hipparcos mission, it is roughly from Earth. It is 1.8 degrees south of the ecliptic. Theta Ophiuchi appears to be a triple star system. The brightest component is a spectroscopic binary with an orbital period of 56.71 days and an eccentricity of 0.17. The third component is 5.5 magnitude star with a stellar classification of B5. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epsilon Ophiuchi
Epsilon Ophiuchi or ε Ophiuchi, formally named Yed Posterior (), is a red giant star in the constellation of Ophiuchus. Located less than five degrees south of the celestial equator in the eastern part of the constellation, it forms a naked eye optical double with Delta Ophiuchi (named ''Yed Prior''). With an apparent visual magnitude of 3.220, the star can be seen with the naked eye from most of the Earth under suitably dark skies. Parallax measurements yield an estimated distance of from the Sun. Nomenclature ''ε Ophiuchi'' ( Latinised to ''Epsilon Ophiuchi'') is the star's Bayer designation. It bore the traditional name ''Yed Posterior''. ''Yed'' derives from the Arabic يد ''yad'' meaning "hand". ''Epsilon'' and ''Delta Ophiuchi'' comprise the left hand of Ophiuchus (the Serpent Bearer) that holds the head of the serpent (Serpens Caput). ''Epsilon'' is ''Yed Posterior'' as it follows ''Delta '' across the sky. In 2016, the International Astronomical Union organiz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kappa Ophiuchi
Kappa Ophiuchi, Latinized from κ Ophiuchi, is a star in the equatorial constellation Ophiuchus. It is a suspected variable star with an average apparent visual magnitude of 3.20, making it visible to the naked eye and one of the brighter members of this constellation. Based upon parallax measurements made during the Hipparcos mission, it is situated at a distance of around from Earth. The overall brightness of the star is diminished by 0.11 magnitudes due to extinction from intervening matter along the line of sight. The spectrum of this star matches a stellar classification of K2 III, with the luminosity class of 'III' indicating this is a giant star that has exhausted the hydrogen at its core and evolved away from the main sequence of stars like the Sun. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. It is 19% more massive than the Sun, but the outer envelope has expanded to around 11 tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta Ophiuchi
Beta Ophiuchi or β Ophiuchi, also named Cebalrai , is a star in the equatorial constellation of Ophiuchus. The apparent visual magnitude of this star is 2.7, which is readily visible to the naked eye even from urban skies. The distance to this star can be estimated using parallax measurements, yielding a value of from the Sun. Nomenclature ''β Ophiuchi'' ( Latinised to ''Beta Ophiuchi'') is the star's Bayer designation. It bore the traditional names ''Cebalrai'', ''Celbalrai'', ''Cheleb'' and ''Kelb Alrai'' (or sometimes just ''Alrai''), all derived from the Arabic كلب الراعي ''kalb al-rā‘ī'' "the shepherd's dog". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name ''Cebalrai'' for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names. Namesake USS Cheleb (AK-138) was a United States Navy Crater class ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delta Ophiuchi
Delta Ophiuchi (δ Ophiuchi, abbreviated Delta Oph, δ Oph), formally named Yed Prior , is a star in the constellation of Ophiuchus. It forms a naked-eye optical double with Epsilon Ophiuchi (named ''Yed Posterior''). The apparent visual magnitude is 2.75, making this a third-magnitude star and the fourth-brightest in the constellation. Parallax measurements from the Hipparcos spacecraft yield a distance estimate of approximately from the Sun (Epsilon Ophiuchi is approximately ). Nomenclature ''δ Ophiuchi'' ( Latinised to ''Delta Ophiuchi'') is the star's Bayer designation. It bore the traditional name ''Yed Prior''. ''Yed'' derives from the Arabic يد ''yad'' "hand". ''Delta'' and ''Epsilon Ophiuchi'' comprise the left hand of Ophiuchus (the Serpent Bearer) that holds the head of the serpent (Serpens Caput). ''Delta'' is ''Yed Prior'' as it leads ''Epsilon'' across the sky. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Be Star
Be stars are a heterogeneous set of stars with B spectral types and emission lines. A narrower definition, sometimes referred to as ''classical Be stars'', is a non-supergiant B star whose spectrum has, or had at some time, one or more Balmer emission lines. Definition and classification Many stars have B-type spectra and show hydrogen emission lines, including many supergiants, Herbig Ae/Be stars, mass-transferring binary systems, and B stars. It is preferred to restrict usage of the term Be star to non-supergiant stars showing one or more Balmer series lines in emission. These are sometimes referred to as classical Be stars. The emission lines may be present only at certain times. Although the Be type spectrum is most strongly produced in class B stars, it is also detected in O and A shell stars, and these are sometimes included under the "Be star" banner. Be stars are primarily considered to be main sequence stars, but a number of subgiants and giant stars are also inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
