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IC 1101
IC 1101 is a class S0 supergiant ( cD) lenticular galaxy at the center of the Abell 2029 galaxy cluster. It has an isophotal diameter at about . It possesses a diffuse core which is the largest known core of any galaxy to date, and also hosts a supermassive black hole that is one of the largest black holes known. The galaxy is located at from Earth. The galaxy was discovered on 19 June 1790, by the British astronomer William Herschel. Characteristics Morphology The galaxy is classified as a supergiant elliptical (E) to lenticular (S0) and is the brightest galaxy in A2029 (hence its other designation A2029-BCG; BCG meaning ''brightest cluster galaxy''). The galaxy's morphological type is debated due to it possibly being shaped like a flat disc but only visible from Earth at its broadest dimensions. A morphology of S0- (Hubble stage -2; see Hubble stage for details) has been given by the Third Reference Catalogue of Bright Galaxies (RC3) in 1991. Size IC 1101 is considered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New General Catalogue
The ''New General Catalogue of Nebulae and Clusters of Stars'' (abbreviated NGC) is an astronomical catalogue of deep-sky objects compiled by John Louis Emil Dreyer in 1888. The NGC contains 7,840 objects, including galaxies, star clusters and emission nebulae. Dreyer published two supplements to the NGC in 1895 and 1908, known as the ''Index Catalogues'' (abbreviated IC), describing a further 5,386 astronomical objects. Thousands of these objects are best known by their NGC or IC numbers, which remain in widespread use. The NGC expanded and consolidated the cataloguing work of William and Caroline Herschel, and John Herschel's ''General Catalogue of Nebulae and Clusters of Stars''. Objects south of the celestial equator are catalogued somewhat less thoroughly, but many were included based on observation by John Herschel or James Dunlop. The NGC contained multiple errors, but attempts to eliminate them were made by the ''Revised New General Catalogue'' (RNGC) by Jack W. Sulent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brightest Cluster Galaxy
A brightest cluster galaxy (BCG) is defined as the brightest galaxy in a cluster of galaxies. BCGs include the most massive galaxies in the universe. They are generally elliptical galaxies which lie close to the geometric and kinematical center of their host galaxy cluster, hence at the bottom of the cluster potential well. They are also generally coincident with the peak of the cluster X-ray emission. Formation scenarios for BCGs include: * Cooling flow—Star formation from the central cooling flow in high density cooling centers of X-ray cluster halos. The study of accretion populations in BCGs has cast doubt over this theory and astronomers have seen no evidence of cooling flows in radiative cooling clusters. The two remaining theories exhibit healthier prospects. * Galactic cannibalism—Galaxies sink to the center of the cluster due to dynamical friction and tidal stripping. * Galactic merger—Rapid galactic mergers between several galaxies take place during cluster col ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Most Massive Black Holes
This is an ordered list of the most massive black holes so far discovered (and probable candidates), measured in units of solar masses (), approximately . Introduction A supermassive black hole (SMBH) is an extremely large black hole, on the order of hundreds of thousands to billions of solar masses (), and is theorized to exist in the center of almost all massive galaxies. In some galaxies, there are even binary systems of supermassive black holes, see the OJ 287 system. Unambiguous dynamical evidence for SMBHs exists only in a handful of galaxies; these include the Milky Way, the Local Group galaxies M31 and M32, and a few galaxies beyond the Local Group, e.g. NGC 4395. In these galaxies, the mean square (or root mean square) velocities of the stars or gas rises as ~1/r near the center, indicating a central point mass. In all other galaxies observed to date, the rms velocities are flat, or even falling, toward the center, making it impossible to state with certainty that a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supermassive Black Hole
A supermassive black hole (SMBH or sometimes SBH) is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions of times the mass of the Sun (). Black holes are a class of astronomical objects that have undergone gravitational collapse, leaving behind spheroidal regions of space from which nothing can escape, not even light. Observational evidence indicates that almost every large galaxy has a supermassive black hole at its Central massive object, center. For example, the Milky Way has a Galactic Center#Supermassive black hole, supermassive black hole in its Galactic Center, corresponding to the Astronomical radio source, radio source Sagittarius A*. Accretion (astrophysics), Accretion of Interstellar medium, interstellar gas onto supermassive black holes is the process responsible for powering Active galactic nucleus, active galactic nuclei (AGNs) and quasars. Two supermassive black holes have been directly imaged by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arecibo Observatory
The Arecibo Observatory, also known as the National Astronomy and Ionosphere Center (NAIC) and formerly known as the Arecibo Ionosphere Observatory, is an observatory in Barrio Esperanza, Arecibo, Puerto Rico owned by the US National Science Foundation (NSF). The observatory's main instrument was the Arecibo Telescope, a spherical reflector dish built into a natural sinkhole, with a cable-mount steerable receiver and several radar transmitters for emitting signals mounted above the dish. Completed in 1963, it was the world's largest single-aperture telescope for 53 years, surpassed in July 2016 by the Five-hundred-meter Aperture Spherical Telescope (FAST) in China. Following two breaks in cables supporting the receiver platform in mid-2020, the NSF decommissioned the telescope. A partial collapse of the telescope occurred on December 1, 2020, before controlled demolition could be conducted. In 2022, the NSF announced the telescope will not be rebuilt, with an educational fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ESO 306-17
ESO 306-17 is a fossil group giant elliptical galaxy An elliptical galaxy is a type of galaxy with an approximately ellipsoidal shape and a smooth, nearly featureless image. They are one of the four main classes of galaxy described by Edwin Hubble in his Hubble sequence and 1936 work ''The R ... in the Columba constellation, about 1 million light-years in diameter, and roughly 500 million light-years away. The galaxy is situated alone in a volume of space about it. It is theorized that the galaxy cannibalized its nearest companions, hence, being a fossil group.Astronomy Now"Bully galaxy rules the neighbourhood" Emily Baldwin, ''4 March 2010'' (accessed 5 March 2010) The galaxy is a giant elliptical of type cD3 (E+3), one of the largest types of galaxies. References * Discovery News"Bully for ESO 306-17" Jennifer Ouellette, ''3 March 2010'' (accessed 5 March 2010) * EurekAlert"ACS Image of ESO 306-17" Colleen Sharkey, ''4 March 2010'' (accessed 5 March 2010) Co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abell 1413
Abell 1413 is a galaxy cluster in the Abell catalogue. The Abell catalogue was published by George O. Abell in 1958 while working on his PhD at California Institute of Technology. The catalogue has two different surveys. The Northern survey was done first by Abell in 1958 with the help of A.G. Wilson. The Northern Survey has 2,712 clusters, and in order for a cluster to be put into the catalogue it must pass four criteria. The first criterion is richness, and Abell divided the clusters into 6 different richness groups. Group 0 was 30-49 galaxies, Group 1 was 50-79 galaxies, Group 2 was 80-129 galaxies, Group 3 was 130 to 199 galaxies, Group 4 was 200-299 galaxies, and Group 5 was more than 299 galaxies. The second criterion was compactness. To meet this requirement a cluster must have 50 or more members in one counting radius of the cluster's center. The third criterion is distance. A cluster must have a nominal redshift between .02 and .2, which means a recessional velocity is betw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGC 623
NGC 623 is a large elliptical galaxy located in the Sculptor constellation at a distance of about 400 million light-years away from the Milky Way. It was discovered by British astronomer John Herschel Sir John Frederick William Herschel, 1st Baronet (; 7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor, experimental photographer who invented the blueprint and did botanical wor ... in 1837. See also * List of NGC objects (1–1000) References Elliptical galaxies Sculptor (constellation) 0623 005898 {{Elliptical-galaxy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2MASS
The Two Micron All-Sky Survey, or 2MASS, was an astronomical survey of the whole sky in infrared light. It took place between 1997 and 2001, in two different locations: at the U.S. Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona, and at the Cerro Tololo Inter-American Observatory in Chile, each using a 1.3-meter telescope for the Northern and Southern Hemisphere, respectively. It was conducted in the short-wavelength infrared at three distinct frequency bands ( J, H, and K) near 2 micrometres, from which the photometric survey with its HgCdTe detectors derives its name. 2MASS produced an astronomical catalog with over 300 million observed objects, including minor planets of the Solar System, brown dwarfs, low-mass stars, nebulae, star clusters and galaxies. In addition, 1 million objects were cataloged in the ''2MASS Extended Source Catalog'' (''2MASX''). The cataloged objects are designated with a "2MASS" and "2MASX"-prefix respectively. Catalog The final d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Largest Galaxies
This is a list of largest galaxies known, sorted by order of increasing major axis diameters. The unit of measurement used is the light-year (approximately 9.46 kilometers). Overview Galaxies are vast collections of stars, planets, nebulae and other objects that are surrounded by an interstellar medium and held together by gravity. They do not have a definite boundary by nature, and are characterized with gradually decreasing stellar density as a function of increasing distance from its center. Because of this, measuring the sizes of galaxies can often be difficult and have a wide range of results depending on the sensitivity of the detection equipment and the methodology being used. Some galaxies emit more strongly in wavelengths outside the visible spectrum, depending on its stellar population, whose stars may emit more strongly in other wavelengths that are beyond the detection range. It is also important to consider the morphology of the galaxy when attempting to measure it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Effective Radius
Galaxy effective radius or half-light radius (R_e) is the radius at which half of the total light of a galaxy is emitted. This assumes the galaxy has either intrinsic spherical symmetry or is at least circularly symmetric as viewed in the plane of the sky. Alternatively, a half-light contour, or isophote, may be used for spherically and circularly asymmetric objects. R_e is an important length scale in \sqrt R term in de Vaucouleurs law, which characterizes a specific rate at which surface brightness In astronomy, surface brightness (SB) quantifies the apparent brightness or flux density per unit angular area of a spatially extended object such as a galaxy or nebula, or of the night sky background. An object's surface brightness depends on it ... decreases as a function of radius: : I(R) = I_e \cdot e^ where I_e is the surface brightness at R = R_e. At R = 0, : I(R=0) = I_e \cdot e^ \approx 2000 \cdot I_e Thus, the central surface brightness is approximately 2000 \cdot I_ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photographic Plate
Photographic plates preceded photographic film as a capture medium in photography, and were still used in some communities up until the late 20th century. The light-sensitive emulsion of silver salts was coated on a glass plate, typically thinner than common window glass. 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, specifically to photograph "The Alton Limited" train owned by the Chicago & Alton Railway. It took photographs on glass plates measuring × . Glass plate photographic material largely faded from the consumer market in the early years of the 20th century, as more convenient and less fragile fil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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