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Abell 2744
Abell 2744, nicknamed Pandora's Cluster, is a giant galaxy cluster resulting from the simultaneous pile-up of at least four separate, smaller galaxy clusters that took place over a span of 350 million years, and is located approximately 4 billion light years from Earth. The galaxies in the cluster make up less than five percent of its mass. The gas (around 20 percent) is so hot that it shines only in X-rays. Dark matter makes up around 75 percent of the cluster's mass. This cluster also shows a radio halo along with several other Abell clusters. It has a strong central halo, along with an extended tail, which could either be relic radiation, or an extension of the central halo. Renato Dupke, a member of the team that discovered the Cluster, explained the origin of the name in an interview: "We nicknamed it ‘''Pandora's Cluster''’ because so many different and strange phenomena were unleashed by the collision." Gallery File:Swimming in Sculptor.jpg, Abell 2744 pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abell Catalogue
The Abell catalog of rich clusters of galaxies is an all-sky catalog of 4,073 rich galaxy clusters of nominal redshift ''z'' ≤ 0.2. This catalog supplements a revision of George O. Abell's original "Northern Survey" of 1958, which had only 2,712 clusters, with a further 1,361 clustersthe "Southern Survey" of 1989, published after Abell's death by co-authors Harold G. Corwin and Ronald P. Olowin from those parts of the south celestial hemisphere that had been omitted from the earlier survey. The Abell catalog, and especially its clusters, are of interest to amateur astronomers as challenge objects to be viewed in dark locations on large aperture amateur telescopes. The Northern Survey The original catalog of 2,712 rich clusters of galaxies was published in 1958 by George O. Abell (1927–1983), who was then studying at the California Institute of Technology. The catalog, which formed part of Abell's PhD thesis, was prepared by means of a visual inspection of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Halo
Radio halos are large-scale sources of diffuse radio emission found in the center of some, but not all, galaxy clusters.Feretti, L., and G. Swarup. "The Universe at Low Radio Frequencies." Proceedings of IAU Symposium. Vol. 199. 2002. There are two classes of radio halos: mini-halos and giant radio halos. The linear size of giant radio halos is about 700kpc-1Mpc, whereas mini-halos are typically less than 500kpc. Giant radio halos are more often observed in highly X-ray luminous cluster samples than less luminous X-ray clusters (\mathrm_X \leq 10^ \mathrm^) in complete samples. They have a very low surface brightness and do not have obvious galaxy counterparts (in contrast to radio galaxies which have AGN counterparts). However, their morphologies typically follow the distribution of gas in the intra-cluster medium. Mini-halos however, while similar to giant halos, are found at the center of cooling core clusters but around a radio galaxy. The cause of radio haloes is still deba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abell Objects
Abell may refer to: People * Abell (surname) * George O. Abell, of the astronomical catalogues fame Places ;United States * Abell, Maryland, a location in St. Mary's County, Maryland * Abell, a neighborhood in Baltimore, Maryland * Abells Corners, Wisconsin, an unincorporated community Astronomy *Abell catalogue The Abell catalog of rich clusters of galaxies is an all-sky catalog of 4,073 rich galaxy clusters of nominal redshift ''z'' ≤ 0.2. This catalog supplements a revision of George O. Abell's original "Northern Survey" of 1958, wh ... of rich clusters of galaxies (ACO) * Abell Catalog of Planetary Nebulae (A) Bibliographical database * ABELL, the ''Annual Bibliography of English Language and Literature'' See also * Abel (other) {{disambiguation, geo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abell 370
Abell 370 is a galaxy cluster located nearly 5 billion light-years away from the Earth (at redshift ''z'' = 0.375), in the constellation Cetus. Its core is made up of several hundred galaxies. It was catalogued by George Abell, and is the most distant of the clusters he catalogued. In the 1980s astronomers of Toulouse Observatory discovered a gravitational lens in space between Earth and Abell 370. A curious arc had been observed earlier near the cluster, but the astronomers were able to recognize it as this phenomenon. Gravitational lensing Abell 370 appears to include several arcs of light, including the largest ever discovered with 30" long. These arcs or deformations are mirages caused by gravitational lensing of massive and dark objects located between the observer and the distant galaxies. This cluster shows an apparent magnitude of +22. In 2002, astronomers used this lensing effect to discover a galaxy, HCM-6A, 12.8 billion light years away from Earth. At the time it wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravitational Lensing
A gravitational lens is a distribution of matter (such as a galaxy cluster, cluster of galaxies) between a distant light source and an observer that is capable of bending the light from the source as the light travels toward the observer. This effect is known as gravitational lensing, and the amount of bending is one of the predictions of Albert Einstein's General relativity, general theory of relativity. Treating light as corpuscles travelling at the speed of light, Newtonian physics also predicts the bending of light, but only half of that predicted by general relativity. Although Einstein made unpublished calculations on the subject in 1912, Orest Khvolson (1924) and Frantisek Link (1936) are generally credited with being the first to discuss the effect in print. However, this effect is more commonly associated with Einstein, who published an article on the subject in 1936. Fritz Zwicky posited in 1937 that the effect could allow galaxy clusters to act as gravitational lense ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galaxies
A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. Galaxies, averaging an estimated 100 million stars, range in size from dwarfs with less than a hundred million stars, to the largest galaxies known – supergiants with one hundred trillion stars, each orbiting its galaxy's center of mass. Most of the mass in a typical galaxy is in the form of dark matter, with only a few percent of that mass visible in the form of stars and nebulae. Supermassive black holes are a common feature at the centres of galaxies. Galaxies are categorized according to their visual morphology as elliptical, spiral, or irregular. Many are thought to have supermassive black holes at their centers. The Milky Way's central black hole, known as Sagittarius A*, has a mass four million times greater than the Sun. As of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hubble Space Telescope
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versatile, renowned both as a vital research tool and as a public relations boon for astronomy. The Hubble telescope is named after astronomer Edwin Hubble and is one of NASA's Great Observatories. The Space Telescope Science Institute (STScI) selects Hubble's targets and processes the resulting data, while the Goddard Space Flight Center (GSFC) controls the spacecraft. Hubble features a mirror, and its five main instruments observe in the ultraviolet, visible, and near-infrared regions of the electromagnetic spectrum. Hubble's orbit outside the distortion of Earth's atmosphere allows it to capture extremely high-resolution images with substantially lower background light than ground-based telescopes. It has recorded some of the most detaile ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Abell Clusters
The Abell catalogue is a catalogue of approximately 4,000 galaxy clusters with at least 30 members, almost complete to a redshift of ''z'' = 0.2. It was originally compiled by the American astronomer George O. Abell in 1958 using plates from POSS, and extended to the southern hemisphere by Abell, Corwin and Olowin in 1987. The name "Abell" is also commonly used as a designation for objects he compiled in a catalogue of 86 planetary nebulae in 1966. The proper designation for the galaxy clusters is ACO, as in "ACO 13", while the planetary-nebula designation is the single letter A, as in "A 39". 1–1999 2000–4076 Southern catalogue S1–S1174 See also * Lists of astronomical objects * List of galaxy groups and clusters This article lists some galaxy groups and galaxy clusters. Defining the limits of galaxy clusters is imprecise as many clusters are still forming. In particular, clusters close to the Milky Way tend to be classified as galaxy clusters eve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dark Matter
Dark matter is a hypothetical form of matter thought to account for approximately 85% of the matter in the universe. Dark matter is called "dark" because it does not appear to interact with the electromagnetic field, which means it does not absorb, reflect, or emit electromagnetic radiation and is, therefore, difficult to detect. Various astrophysical observationsincluding gravitational effects which cannot be explained by currently accepted theories of gravity unless more matter is present than can be seenimply dark matter's presence. For this reason, most experts think that dark matter is abundant in the universe and has had a strong influence on its structure and evolution. The primary evidence for dark matter comes from calculations showing that many galaxies would behave quite differently if they did not contain a large amount of unseen matter. Some galaxies would not have formed at all and others would not move as they currently do. Other lines of evidence include observa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galaxy
A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. Galaxies, averaging an estimated 100 million stars, range in size from dwarfs with less than a hundred million stars, to the largest galaxies known – supergiants with one hundred trillion stars, each orbiting its galaxy's center of mass. Most of the mass in a typical galaxy is in the form of dark matter, with only a few percent of that mass visible in the form of stars and nebulae. Supermassive black holes are a common feature at the centres of galaxies. Galaxies are categorized according to their visual morphology as elliptical, spiral, or irregular. Many are thought to have supermassive black holes at their centers. The Milky Way's central black hole, known as Sagittarius A*, has a mass four million times greater than the Sun. As o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galaxy Cluster
A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to 1015 solar masses. They are the second-largest known gravitationally bound structures in the universe after galaxy filaments and were believed to be the largest known structures in the universe until the 1980s, when superclusters were discovered. One of the key features of clusters is the intracluster medium (ICM). The ICM consists of heated gas between the galaxies and has a peak temperature between 2–15 keV that is dependent on the total mass of the cluster. Galaxy clusters should not be confused with ''galactic clusters'' (also known as open clusters), which are star clusters ''within'' galaxies, or with globular clusters, which typically orbit galaxies. Small aggregates of galaxies are referred to as galaxy groups rather than clusters of galaxies. The galaxy groups and c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
