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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. 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 found to have a luminosity of and an effective temperature of 2,858 K in the year 1900, and a luminosity of and a temperature of 3,614K in the year 2000. It is one of largest stars known, at its brightest and coolest calculated to be compared to at its hottest and faintest. If it were in the place of the Sun, its photosphere would engulf the entire inner Solar System and reach close to the orbit of Jupiter. With a mass of about , it is estimated that the stellar mass loss, as dust, as the atomic and molec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
γ Cygni
Gamma Cygni is a star in the northern constellation of Cygnus, forming the intersection of an asterism of five stars called the Northern Cross. It is officially named Sadr , gamma Cygni is its Bayer designation, which that is Latinized from γ Cygni, and abbreviated Gamma Cyg or γ Cyg. Based upon parallax measurements obtained during the Hipparcos mission, it is approximately 1,800 light-years (560 parsecs) from the Sun. It forms the primary or 'A' component of a multiple star system designated WDS J20222+4015 (the secondary or 'BCD' component is WDS J20222+4015BCD, a close triplet of stars 41" away from γ Cygni). Nomenclature ''γ Cygni'' ( Latinised to ''Gamma Cygni'') is the star's Bayer designation. WDS J20222+4015A is its designation in the Washington Double Star Catalog. It bore the traditional name ''Sadr'' (also rendered ''Sadir'' or ''Sador''), derived from the Arabic صدر ''ṣadr'' "chest", the same word which gave rise to the star Schedar ( Alp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kelvin
The kelvin (symbol: K) is the base unit for temperature in the International System of Units (SI). The Kelvin scale is an absolute temperature scale that starts at the lowest possible temperature (absolute zero), taken to be 0 K. By definition, the Celsius scale (symbol °C) and the Kelvin scale have the exact same magnitude; that is, a rise of 1 K is equal to a rise of 1 °C and vice versa, and any temperature in degrees Celsius can be converted to kelvin by adding 273.15. The 19th century British scientist Lord Kelvin first developed and proposed the scale. It was often called the "absolute Celsius" scale in the early 20th century. The kelvin was formally added to the International System of Units in 1954, defining 273.16 K to be the triple point of water. The Celsius, Fahrenheit, and Rankine scales were redefined in terms of the Kelvin scale using this definition. The 2019 revision of the SI now defines the kelvin in terms of energy by setting the Bo ... [...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. It shows 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 suc ... [...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 AC power plugs and sockets: British and related types#BS 546, 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) * Class M (other) {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RW Cygni
RW Cygni is a semiregular variable star in the constellation Cygnus (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 cal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
KY Cygni
KY Cygni is a variable red supergiant of spectral class M3Ia located in the constellation Cygnus. It is approximately 4,700 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 m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NML Cygni
NML Cygni or V1489 Cygni (abbreviated to NML Cyg or V1489 Cyg) is a M-type star, red hypergiant or red supergiant (RSG) in the constellation Cygnus (constellation), Cygnus. It is possibly one of the List of largest stars, largest known stars currently known, and is also possibly list of most luminous stars, one of the most luminous and List of most massive stars, massive cool hypergiants, as well as one of the most luminous stars in the Milky Way. The distance of NML Cygni from Earth is estimated to be around 1.6 Parsec#Parsecs and kiloparsecs, kpc, about . It is a part of the Cygnus OB2 association, one of the closest massive associations to the Sun, spanning nearly 2° on the sky or ~ in radius at the distance of . Based on the estimated distance and a measurement of its angular diameter of , NML Cygni's physical radius is estimated to be . If placed at the center of the Solar System, its surface would potentially extend past the orbit of Jupiter. Observational history ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visual Magnitude
Apparent magnitude () is a measure of the brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction of the object's light caused by interstellar dust along the line of sight to the observer. Unless stated otherwise, the word ''magnitude'' in astronomy usually refers to a celestial object's apparent magnitude. The magnitude scale likely dates to before the ancient Roman astronomer Claudius Ptolemy, whose star catalog popularized the system by listing stars from 1st magnitude (brightest) to 6th magnitude (dimmest). The modern scale was mathematically defined to closely match this historical system by Norman Pogson in 1856. The scale is reverse logarithmic: the brighter an object is, the lower its magnitude number. A difference of 1.0 in magnitude corresponds to the brightness ratio of \sqrt /math>, or about 2.512. For example, a magnitude 2.0 star is 2. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variable Star Designation
In astronomy, a variable-star designation is a unique identifier given to variable stars. It extends the Bayer designation format, with an identifying label (as described below) preceding the Latin genitive of the name of the constellation in which the star lies. The identifying label can be one or two Latin letters or a ''V'' plus a number (e.g. V399). Examples are R Coronae Borealis, YZ Ceti, V603 Aquilae. (''See'' List of constellations ''for a list of constellations and the genitive forms of their names''.) Naming The current naming system is: * Stars with existing Greek letter Bayer designations are not given new designations. * Otherwise, start with the letter R and go through Z. * Continue with RR–RZ, then use SS–SZ, TT–TZ and so on until ZZ. * After ZZ return to the beginning of the Latin alphabet and use AA–AZ, BB–BZ, CC–CZ, and so on, until reaching QZ, but omitting the letter J in either first or second position. * Abandon the Latin letters after all ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photographic Plate
Photographic plates preceded film as the primary medium for capturing images in photography. These plates, made of metal or glass and coated with a light-sensitive emulsion, were integral to early photographic processes such as heliography, daguerreotypes, and photogravure. Glass plates, thinner than standard window glass, became widely used in the late 19th century for their clarity and reliability. Although largely replaced by film during the 20th century, plates continued to be used for specialised scientific and medical purposes until the late 20th century. History Glass plates were far superior to film for research-quality imaging because they were stable and less likely to bend or distort, especially in large-format frames for wide-field imaging. Early plates used the wet collodion process. The wet plate process was replaced late in the 19th century by gelatin dry plates. A view camera nicknamed "The Mammoth" weighing was built by George R. Lawrence in 1899, sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jupiter
Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined and slightly less than one-thousandth the mass of the Sun. Its diameter is 11 times that of Earth and a tenth that of the Sun. Jupiter orbits the Sun at a distance of , with an orbital period of . It is the List of brightest natural objects in the sky, third-brightest natural object in the Earth's night sky, after the Moon and Venus, and has been observed since prehistoric times. Its name derives from that of Jupiter (god), Jupiter, the chief deity of ancient Roman religion. Jupiter was the first of the Sun's planets to form, and its inward migration during the primordial phase of the Solar System affected much of the formation history of the other planets. Jupiter's atmosphere consists of 76% hydrogen and 24% helium by mass, with a denser ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
