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Beta Ursae Minoris
Beta Ursae Minoris (β Ursae Minoris, abbreviated β UMi, Beta UMi), formally named Kochab , is the brightest star in the bowl of the Little Dipper asterism (which is part of the constellation of Ursa Minor), and only slightly fainter than Polaris, the northern pole star and brightest star in Ursa Minor. Kochab is 16 degrees from Polaris and has an apparent visual magnitude of 2.08. The distance to this star from the Sun can be deduced from the parallax measurements made during the Hipparcos mission, yielding a value of . Amateur astronomers can use Kochab as a precise guide for equatorial mount alignment: The celestial north pole is located 38 arcminutes away from Polaris, very close to the line connecting Polaris with Kochab. Nomenclature ''β Ursae Minoris'' ( Latinised to ''Beta Ursae Minoris'') is the star's Bayer designation. It bore the traditional name ''Kochab'', which appeared in the Renaissance and has an uncertain meaning. It may be from ar, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ursa Minor
Ursa Minor (Latin: 'Lesser Bear', contrasting with Ursa Major), also known as the Little Bear, is a constellation located in the far northern sky. As with the Great Bear, the tail of the Little Bear may also be seen as the handle of a ladle, hence the North American name, Little Dipper: seven stars with four in its bowl like its partner the Big Dipper. Ursa Minor was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and remains one of the 88 modern constellations. Ursa Minor has traditionally been important for navigation, particularly by mariners, because of Polaris being the north pole star. Polaris, the brightest star in the constellation, is a yellow-white supergiant and the brightest Cepheid variable star in the night sky, ranging in apparent magnitude from 1.97 to 2.00. Beta Ursae Minoris, also known as Kochab, is an aging star that has swollen and cooled to become an orange giant with an apparent magnitude of 2.08, only slightly fainter than Po ... [...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] |
Stellar Evolution
Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe. The table shows the lifetimes of stars as a function of their masses. All stars are formed from collapsing clouds of gas and dust, often called nebulae or molecular clouds. Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main-sequence star. Nuclear fusion powers a star for most of its existence. Initially the energy is generated by the fusion of hydrogen atoms at the core of the main-sequence star. Later, as the preponderance of atoms at the core becomes helium, stars like the Sun begin to fuse hydrogen along a spherical shell surrounding the core. This process causes the star to gradually grow in size, passing throug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Luminosity
The solar luminosity (), is a unit of radiant flux (power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun. One nominal solar luminosity is defined by the International Astronomical Union to be . This does not include the solar neutrino luminosity, which would add , or , i.e. a total of (the mean energy of the solar photons is 26 MeV and that of the solar neutrinos 0.59 MeV, i.e. 2.27%; the Sun emits photons and as many neutrinos each second, of which per m2 reach the Earth each second). The Sun is a weakly variable star, and its actual luminosity therefore fluctuates. The major fluctuation is the eleven-year solar cycle (sunspot cycle) that causes a quasi-periodic variation of about ±0.1%. Other variations over the last 200–300 years are thought to be much smaller than this. Determination Solar luminosity is related to solar irradiance (the solar c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Classification
In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction grating into a spectrum exhibiting the Continuum (spectrum), rainbow of colors interspersed with spectral lines. Each line indicates a particular chemical element or molecule, with the line strength indicating the abundance of that element. The strengths of the different spectral lines vary mainly due to the temperature of the photosphere, although in some cases there are true abundance differences. The ''spectral class'' of a star is a short code primarily summarizing the ionization state, giving an objective measure of the photosphere's temperature. Most stars are currently classified under the Morgan–Keenan (MK) system using the letters ''O'', ''B'', ''A'', ''F'', ''G'', ''K'', and ''M'', a sequence from the hottest (''O'' type) to the coo ... [...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] |
Chinese Star Name
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, e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Σ 1694
Struve 1694 (Σ 1694, Struve 1694) is a double star in the constellation Camelopardalis. Σ 1694 is a double star, with components of magnitudes 5.3m and 5.9m: *Σ 1694A ( HD 112028) is a white A-type giant star with an apparent magnitude of 5.28m. It is approximately 300 light years from Earth. *Σ 1694B ( HD 112014) is a spectroscopic binary consisting of two A-type main sequence stars. Norton's Star Atlas describes the pair as yellowish and bluish. Σ 1694 was also known as 32H. Camelopardalis, Hevelius' 32nd of Camelopardalis. It is not Flamsteed's "32 Camelopardalis", which is ξ Aurigae. In the ''British Association Catalogue'', the star pair are listed as being in Ursa Minor. Chinese name In Chinese, (), meaning ''North Pole'', refers to an asterism consisting of Σ 1694, γ Ursae Minoris, β Ursae Minoris, 5 Ursae Minoris and 4 Ursae Minoris. Consequently, Σ 1694 itself is known as (, en, the Fifth Star of North Pole.), representing (), meaning ''C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4 Ursae Minoris
4 Ursae Minoris is a binary star system in the northern circumpolar constellation Ursa Minor. It is faintly visible to the naked eye with an apparent visual magnitude of 4.80. Based upon an annual parallax shift of as seen from Earth's orbit, it is located roughly 460 light years from the Sun. It is moving further away with a heliocentric radial velocity of +5.9 km/s. This is a single-lined spectroscopic binary star system with an orbital period of 1.66 years and an eccentricity of 0.14. The primary is a red giant of spectral type K3-IIIb Fe-0.5, a star that has used up its core hydrogen and is expanding. The suffix notation indicates the spectrum displays a mild underabundance of iron for a star of its type. It has expanded to around 28 times the Sun's radius and is radiating 437 times the Sun's luminosity The solar luminosity (), is a unit of radiant flux (power emitted in the form of photons) conventionally used by astronomers to measure th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
5 Ursae Minoris
5 Ursae Minoris is a star in the circumpolar constellation of Ursa Minor. It is a faint star but visible to the naked eye with an apparent visual magnitude of 4.253. The distance to this star, as determined from an annual parallax shift of , is about 110 pc. It is moving further away with a heliocentric radial velocity of +9 km/s. With an age of around two billion years, this is an evolved red giant with a stellar classification of K4-III; a star that has used up its core hydrogen and has expanded. It is a mild barium star, which may indicate it is a binary with a white dwarf companion, and is very lithium-weak. The star has an estimated 1.86 times the mass of the Sun and has expanded to about 16 times the Sun's radius. It is radiating 447 times the Sun's luminosity from its enlarged 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 ele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gamma Ursae Minoris
Gamma Ursae Minoris (γ Ursae Minoris, abbreviated Gamma UMi, γ UMi), also named Pherkad , is a star in the northern constellation of Ursa Minor. Together with Beta Ursae Minoris (Kochab), it forms the end of the dipper pan of the "Little Dipper", which is an asterism forming the tail of the bear. Based upon parallax measurements obtained during the Hipparcos mission, it is approximately from the Sun. Nomenclature ''γ Ursae Minoris'' ( Latinised to ''Gamma Ursae Minoris'') is the star's Bayer designation. The fainter 11 Ursae Minoris has been called ''γ¹ Ursae Minoris'', in which case ''Gamma Ursae Minoris'' would be designated ''γ²''. However this usage is rarely seen. Gamma Ursae Minoris bore the traditional name ''Pherkad'', which derived from the Arabic فرقد ''farqad'' "calf", short for ''aḫfa al farkadayn'' "the dim one of the two calves", that is Pherkad and Kochab (the full name Ahfa al Farkadain is traditionally applied to Zeta Ursae Minoris). Gamma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Purple Forbidden Enclosure
The Purple Forbidden enclosure ( Zǐ wēi yuán) is one of the San Yuan ( Sān yuán) or Three Enclosures Traditional Chinese astronomy has a system of dividing the celestial sphere into asterisms or constellations, known as "officials" ( Chinese ''xīng guān''). The Chinese asterisms are generally smaller than the constellations of Hellenistic .... Stars and constellations of this group lie near the north celestial pole and are visible all year from temperate latitudes in the Northern Hemisphere. Asterisms The asterisms are : See also * Twenty-eight mansions References Chinese constellations Chinese astrology {{china-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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