|
Mu Pegasi
Mu Pegasi or μ Pegasi, formally named Sadalbari (), is a star in the northern constellation of Pegasus. The apparent visual magnitude of this star is 3.5, which is bright enough to be seen with the naked eye even on a moonlit night. Based upon parallax measurements taken during the Hipparcos mission, it is approximately from the Sun. Nomenclature ''μ Pegasi'' ( Latinised to ''Mu Pegasi'') is the star's Bayer designation. It bore the traditional name ''Sadalbari'', which derives from ar, سعد بارع ''saʿd al-bāriʿ'', the “auspicious star of the splendid one.” 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 ''Sadalbari'' for this star on 21 August 2016 and it is now so included in the List of IAU-approved Star Names. In Chinese, (), meaning '' Resting Palace'', refers to an asterism consisting of Mu Pegasi, Lambda Pegasi, Omicron P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
J2000
In astronomy, an epoch or reference epoch is a instant, moment in time used as a reference point for some time-varying astronomical quantity. It is useful for the celestial coordinates or orbital elements of a Astronomical object, celestial body, as they are subject to Perturbation (astronomy), perturbations and vary with time. These time-varying astronomical quantities might include, for example, the mean longitude or mean anomaly of a body, the node of its orbit relative to a reference plane, the direction of the apogee or Perihelion and aphelion, aphelion of its orbit, or the size of the major axis of its orbit. The main use of astronomical quantities specified in this way is to calculate other relevant parameters of motion, in order to predict future positions and velocities. The applied tools of the disciplines of celestial mechanics or its subfield orbital mechanics (for predicting orbital paths and positions for bodies in motion under the gravitational effects of other bodi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encampment (Chinese Constellation)
The Encampment mansion () is one of the 28 mansions of the Chinese constellations. It is one of the northern mansions of the Black Tortoise The Black Tortoise () is one of the Four Symbols of the Chinese constellations. Despite its English name, it is usually depicted as a tortoise entwined together with a snake. The name used in East Asian languages does not mention either anima .... Asterisms References {{DEFAULTSORT:Encampment (Chinese Constellation) Chinese constellations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Mass
The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass of the Sun. This equates to about two nonillion (short scale), two quintillion (long scale) kilograms or 2000 quettagrams: The solar mass is about times the mass of Earth (), or times the mass of Jupiter (). History of measurement The value of the gravitational constant was first derived from measurements that were made by Henry Cavendish in 1798 with a torsion balance. The value he obtained differs by only 1% from the modern value, but was not as precise. The diurnal parallax of the Sun was accurately measured during the transits of Venus in 1761 and 1769, yielding a value of (9 arcseconds, compared to the present value of ). From the value of the diurnal parallax, one can determine the distance to the Sun from the geometry o ... [...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] |
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] |
Luminosity Class
In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the 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 coolest (''M'' type). Each letter class is then subdivided ... [...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] |
Stellar Spectrum
Astronomical spectroscopy is the study of astronomy using the techniques of spectroscopy to measure the spectrum of electromagnetic radiation, including visible light, ultraviolet, X-ray, infrared and radio waves that radiate from stars and other celestial objects. A stellar spectrum can reveal many properties of stars, such as their chemical composition, temperature, density, mass, distance and luminosity. Spectroscopy can show the velocity of motion towards or away from the observer by measuring the Doppler shift. Spectroscopy is also used to study the physical properties of many other types of celestial objects such as planets, nebulae, galaxies, and active galactic nuclei. Background Astronomical spectroscopy is used to measure three major bands of radiation in the electromagnetic spectrum: visible light, radio waves, and X-rays. While all spectroscopy looks at specific bands of the spectrum, different methods are required to acquire the signal depending on the frequency. ... [...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] |
Nu Pegasi
ν Pegasi, Latinized as Nu Pegasi is a single star in the northern constellation of Pegasus. It is an orange-hued star that is faintly visible to the naked eye with an apparent visual magnitude of 4.84. The star is located approximately away based on parallax, but is drifting closer with a radial velocity of . This is an aging giant star, most likely (94% chance) on the red giant branch, with a stellar classification of K4III. It is a suspected variable, with a magnitude range observed from 4.83 to 4.86. With the supply of hydrogen at its core exhausted, the star has cooled and expanded to 24.6 times the Sun's radius. It is 13% more massive than the Sun and is radiating 149 times the Sun's luminosity 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 est ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tau Pegasi
Tau Pegasi (τ Pegasi, abbreviated Tau Peg, τ Peg), formally named Salm , is a magnitude 4.6 star 162 light years away in the constellation of Pegasus. With about twice the mass of the Sun and thirty times as luminous, tt is a δ Scuti variable star with its brightness changing by a few hundredths of a magnitude over about an hour. Nomenclature ''τ Pegasi'' ( Latinised to ''Tau Pegasi'') is the star's Bayer designation. The star bore the traditional names ''Salm'', ''Kerb'' (or ''El Khereb'') and ''Markab'' (often spelled ''Markeb''), a name shared with Alpha Pegasi, k Puppis and Kappa Velorum. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN approved the name ''Salm'' (a homophone with the planet Samh) for this star and ''Markeb'' for the component Kappa Velorum A, both on 5 September 2017. ''Markab'' had previously been approved for Alpha Pegasi on 30 June 2016. All three are now so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eta Pegasi
Eta Pegasi or η Pegasi, formally named Matar , is a binary star in the constellation of Pegasus. The apparent visual magnitude of this star is +2.95, making it the fifth-brightest member of Pegasus. Based upon parallax measurements, the distance to this star is about from the Sun. Nomenclature ''η Pegasi'' ( Latinised to ''Eta Pegasi'') is the star's Bayer designation. It bore the traditional name ''Matar'', derived from the Arabic سعد المطر ''Al Saʽd al Maṭar'', meaning ''lucky star of rain''. 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 ''Matar'' for this star on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names. In Chinese, (), meaning '' Resting Palace'', refers to an asterism consisting η Pegasi, λ Pegasi, μ Pegasi, ο Pegasi, τ Pegasi and ν Pegasi. Consequently, η Pegasi itself is known as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
