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RW Cygni
RW Cygni is a semiregular variable star in the constellation Cygnus, about a degree east of 2nd magnitude γ Cygni. Its apparent magnitude varies between 8.05 and 9.70 and its spectral type between M3 and M4. Distance The Gaia Data Release 2 parallax for RW Cyg is or a distance of around . RW Cygni is assumed to be a member of the Cygnus OB9 Stellar Association and therefore around 3,600 light-years from the Solar System. Newer observations based on the parallaxes of neighbouring OB stars give RW Cygni a distance of . Properties RW Cygni is a luminous red supergiant with a bolometric luminosity more than . Its spectral type is given in the General Catalogue of Variable Stars as M2-4Ia-Iab, covering the range of previously published values. It has been defined as a standard star for the MK spectral classification of M3-M4Ia-Iab. In 2005, the effective temperature is directly calculated to be 3,600 K, giving a radius of . An alternate calculation gives a higher ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sadr Region Rgb
The Sahrawi Arab Democratic Republic (; SADR; also romanized with Saharawi; ar, الجمهورية العربية الصحراوية الديمقراطية ' es, República Árabe Saharaui Democrática), also known as Western Sahara, is a partially recognized state, recognised by 45 UN member states, located in the western Maghreb, which claims the non-self-governing territory of Western Sahara, but controls only the easternmost one-fifth of that territory. Between 1884 and 1975, Western Sahara was known as Spanish Sahara, a Spanish colony (later an overseas province). The SADR is one of the two African states in which Spanish is a significant language, the other being Equatorial Guinea. The SADR was proclaimed by the Polisario Front (a former socialist liberation force which has since reformed its ideological and political views) on 27 February 1976, in Bir Lehlou, Western Sahara. The SADR government controls about 20–25% of the territory it claims. It calls the t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Largest Stars
Below are lists of the largest stars currently known, ordered by radius and separated into categories by galaxy. The unit of measurement used is the Solar radius, radius of the Sun (approximately ). The angular diameters of stars can be measured directly using Astronomical optical interferometry, stellar interferometry. Other methods can use lunar occultations or from eclipsing binaries, which can be used to test indirect methods of finding stellar radii. Only a few useful supergiant stars can be occulted by the Moon, including Antares A (Alpha Scorpii A). Examples of eclipsing binaries are Epsilon Aurigae (Almaaz), VV Cephei, and V766 Centauri (HR 5171). Angular diameter measurements can be inconsistent because the boundary of the very tenuous atmosphere (Opacity (optics), opacity) differs depending on the wavelength of light in which the star is observed. Uncertainties remain with the membership and order of the lists, especially when deriving various parameters used in calcu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Objects With Variable Star Designations
Object may refer to: General meanings * Object (philosophy), a thing, being, or concept ** Object (abstract), an object which does not exist at any particular time or place ** Physical object, an identifiable collection of matter * Goal, an aim, target, or objective * Object (grammar), a sentence element, such as a direct object or an indirect object Science, technology, and mathematics Computing * 3D model, a representation of a physical object * Object (computer science), a language mechanism for binding data with methods that operate on that data ** Object-orientation, in which concepts are represented as objects *** Object-oriented programming (OOP), in which an object is an instance of a class or array ** Object (IBM i), the fundamental unit of data storage in the IBM i operating system * Object (image processing), a portion of an image interpreted as a unit * Object file, the output of a compiler or other translator program (also known as "object code") * Object, an in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Durchmusterung Objects
In astronomy, Durchmusterung or Bonner Durchmusterung (BD) is an astrometric star catalogue of the whole sky, compiled by the Bonn Observatory in Germany from 1859 to 1903. The name comes from ('run-through examination'), a German word used for a systematic survey of objects or data. The term has sometimes been used for other astronomical surveys, including not only stars, but also the search for other celestial objects. Special tasks include celestial scanning in electromagnetic wavelengths shorter or longer than visible light waves. Original catalog The 44 years of work on the Bonner Durchmusterung (abbreviated BD), initiated by Friedrich Argelander and largely carried out by his assistants, resulted in a catalogue of the positions and apparent magnitudes of approximately 325,000 stars to apparent magnitude 9–10. The catalogue was accompanied by charts plotting the positions of the stars, and was the basis for the ''Astronomische Gesellschaft Katalog'' (AGK) and ''Smithsonia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Semiregular Variable Stars
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] |
Hipparcos Objects
''Hipparcos'' was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial objects on the sky. This permitted the first high-precision measurements of the intrinsic brightnesses (compared to the less precise apparent brightness), proper motions, and parallaxes of stars, enabling better calculations of their distance and tangential velocity. When combined with radial velocity measurements from spectroscopy, astrophysicists were able to finally measure all six quantities needed to determine the motion of stars. The resulting ''Hipparcos Catalogue'', a high-precision catalogue of more than 118,200 stars, was published in 1997. The lower-precision ''Tycho Catalogue'' of more than a million stars was published at the same time, while the enhanced Tycho-2 Catalogue of 2.5 million stars was published in 2000. ''Hipparcos'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
M-type Supergiants
Type M or M type may refer to: Science and technology * Type M, a xD-Picture Card * Type M, a name for the 15 amp BS 546 electrical plug * Vaio Type M, a kind of Vaio computer from Sony * M-type asteroid * m-type filter, an electronic filter * M-type star * M-types, an implementation of inductive type Other uses * Audi Type M, a 1920s car * Beretta 92FS Compact Type M, a pistol * MG M-type, a sports car See also * M class (other) M class or M-class may refer to: Military * M-class cruiser, a planned German light cruiser class * M-class destroyer, several classes of destroyer ** Admiralty M-class destroyer, a class of British destroyers built 1913–1916 and served in World ... * Class M (other) {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
KY Cygni
KY Cygni is a red supergiant of spectral class M3.5Ia located in the constellation Cygnus. It is approximately 5,000 light-years away. Observations KY Cyg lies near the bright open cluster NGC 6913, but is not thought to be a member. The location is close to the bright star γ Cygni. It was identified as a variable star in 1930, and later named as KY Cygni. The spectrum was given the MK classification of M3 Ia, with only minor adjustments since. KY Cygni is heavily reddened due to interstellar extinction, losing an estimated 7.75 magnitudes at visual wavelengths. It would be a naked eye star if no light was lost. Properties KY Cygni is classified as a luminous red supergiant with a strong stellar wind. It is losing mass at around and has been described as a cool hypergiant. Its properties are uncertain, but the temperature is around 3,500 K. A model fit based on K-band infrared brightness gives a luminosity of , corresponding to a radius of . Another model ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BI Cygni
BI Cygni (BI Cyg, IRC +40408, BD+36 4025) is a red supergiant in the constellation Cygnus. It is an irregular variable star with a maximum brightness of magnitude 8.4 and a minimum of magnitude 9.9. It is considered a member of the stellar Cygnus OB1 association, its distance is around of the Solar System. It is less than a degree south of another variable red supergiant, BC Cygni. BI Cyg is a slow irregular variable star classified as type Lc, an irregular supergiant. Its brightness changes between extremes of magnitude 8.4 and 9.9. Frequency analysis of its light curve shows no significant periods. BI Cyg is one of the largest known stars with a radius around based on the assumption of an effective temperature of 3,575 K and a bolometric luminosity of . More recent studies derive lower luminosities below , suggesting an initial mass of , and consequently lower values for the radius. See also *RW Cygni RW Cygni is a semiregular variable s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BC Cygni
BC Cygni (BC Cyg, HIP 100404, BD + 37 3903) is a red supergiant and pulsating variable star of spectral type M3.5Ia in the constellation Cygnus (constellation), Cygnus. It is considered a member of the stellar Cygnus OB1 association, and within it the open cluster Berkeley 87, which would place at a distance of of the Solar System; it is less than a degree north of another variable red supergiant, BI Cygni. According to its Gaia Data Release 3 parallax, it is at about . BC Cygni was calculated to have an effective temperature of 2,858 to 3,614 Kelvin, K and to vary between . The size at its brightest and coolest has been calculated to be compared to at the hottest and faintest. It is List of largest stars, one of largest stars known. If it were in the place of the Sun, its photosphere would engulf the orbit of Jupiter assuming the maximum radius of . With a mass of about , it is estimated that the stellar mass loss, as dust, as the atomic and molecular gas could not ... [...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] |
