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Musket Ball Cluster
The Musket Ball Cluster (DLSCL J0916.2+2951) is a galaxy cluster that exhibits separation between its baryonic matter and dark matter components. The cluster is a recent merger of two galaxy clusters. It is named after the Bullet Cluster, as it is a slower collision, and older than the Bullet Cluster. This cluster is further along the process of merger than the Bullet Cluster, being some 500 million years older, at 700 million years old. The cluster was discovered in 2011 by the Deep Lens Survey. As of 2012, it is one of the few galaxy clusters to show separation between its dark matter and baryonic matter components. Characteristics As of 2012, it is one of seven galaxy clusters that exhibit separation of dark matter and baryonic matter following cluster collision and merger. The separation between the galaxies and their dark matter components is on average . This separation may indicate that dark matter may interact with itself, through a dark force (a force that only interac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
J2000
In astronomy, an epoch or reference epoch is a 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 celestial body, as they are subject to 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 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 bodies) can be used to generate an ephemeris, a table of values giving the positions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fundamental Interaction
In physics, the fundamental interactions, also known as fundamental forces, are the interactions that do not appear to be reducible to more basic interactions. There are four fundamental interactions known to exist: the gravitational and electromagnetic interactions, which produce significant long-range forces whose effects can be seen directly in everyday life, and the strong and weak interactions, which produce forces at minuscule, subatomic distances and govern nuclear interactions. Some scientists hypothesize that a fifth force might exist, but these hypotheses remain speculative. Each of the known fundamental interactions can be described mathematically as a '' field''. The gravitational force is attributed to the curvature of spacetime, described by Einstein's general theory of relativity. The other three are discrete quantum fields, and their interactions are mediated by elementary particles described by the Standard Model of particle physics. Within the Standard M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abell 1759
{{disambiguation, geo ...
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 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) Abel was a son of Adam and Eve in the Bible. According to the Bible, he was the first person to die, murdered by his brother Cain. Abel may also refer to: People and fictional characters * Abel (given name), including a list of people and ficti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abell 2163
Abell 2163 is one of the richest and most distant of the clusters of galaxies found in the Abell catalogue. Its abell richness class is 2 and position is at a redshift z=0.2. Data from Chandra X-ray Observatory have shown that it is the hottest galaxy cluster in the Abell catalogue. It is also a merging cluster. The galaxy density and mass distribution in the central region of this cluster have also been determined by weak gravitational lensing. These analyses show very similar mass and galaxy distributions, with two coincident maxima and a flat shape elongated in the east-west direction, but the weak lensing signal is surprisingly faint in comparison to what could be expected from the cluster X-ray properties. However, these detailed studies are limited to the inner 8’×8’ region of the cluster, and do not include the peripheral clumps such as A2163-B. La Barbera et al. (2004) estimated the photometric redshifts of galaxies in A2163-B, showing that this structure lies at the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 par ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abell 520
The Abell 520 galaxy cluster possesses an unusual substructure resulting from a major merger. It has been popularly nicknamed The Train Wreck Cluster, due to its chaotic structure, and is classified as a Bautz-Morgan type III cluster. It is at a co-moving radial distance of and subtends 25 arcminutes on the sky. Analysis of the motions of 293 galaxies in the cluster field suggested that Abell 520 was a cluster forming at the crossing of three filaments of the large scale structure. The surprising substructure of Abell 520 was reported in 2007 from a weak gravitational lensing study based on Canada-France-Hawaii-Telescope (CFHT) imaging data. It was surprising at first, because the study found the "dark core" with a significant amount of mass in the region, where there is no concentration of bright cluster galaxies. No conventional understanding of dark matter could explain this peculiar concentration of dark matter. At the time, some thought that the substructure may arise ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MACS J0025
MACS J0025.4-1222 is a galaxy cluster created by the collision of two galaxy clusters, and is part of the MAssive Cluster Survey (MACS). Like the earlier discovered Bullet Cluster, this cluster shows a clear separation between the centroid of the intergalactic gas (of majority of the normal, or baryonic, mass) and the colliding clusters. In the image, intergalactic gas is shown in pink and the mass centroids of the colliding clusters in blue, showing the separation of the two, similar to the Bullet Cluster. It provides independent, direct evidence for dark matter and supports the view that dark matter particles interact with each other only very weakly. Details The shown image is a composite of separate exposures made by Hubble Space Telescope ACS and WFPC2 detectors and the Chandra ACIS detector. The Hubble images were taken on November 5, 2006, and June 6, 2007. The visible light images from Hubble showed gravitational lensing which allowed astronomers to infer the distri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bullet Group
The Bullet Group (SL2S J08544-0121) is a newly merging group of galaxies, a merger between two galaxy groups to form a new larger one, that recently had a high speed collision between the two component groups. The group exhibits separation between its dark matter and baryonic matter components. The galaxies occur in two clumps, while the gas has expanded into a billowing cloud encompassing all three clumps. As of 2014, it is one of the few galaxy clusters known to show separation between the dark matter and baryonic matter components. The group is named after the Bullet Cluster, a similar merging galaxy cluster, except on a smaller scale, being of groups instead of clusters. The bimodal distribution of galaxies was found at discovery in 2008. The galaxy group is a gravitational lens and strongly lenses a more distant galaxy behind it, at z=~1.2 Characteristics As of 2014, the group is the smallest mass object to exhibit separation between its dark matter and baryonic matter comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Million Years
The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago). Together they make a reference system, one to a quantity, the other to a particular place in a year numbering system that is ''time before the present''. Myr is deprecated in geology, but in astronomy ''Myr'' is standard. Where "myr" ''is'' seen in geology it is usually "Myr" (a unit of mega-years). In astronomy it is usually "Myr" (Million years). Debate In geology a debate remains open concerning the use of ''Myr'' (duration) plus ''Ma'' (million years ago) versus using only the term ''Ma''. In either case the term '' Ma'' is used in geology literature conforming to ISO 31-1 (now ISO 80000-3) and NIST 811 recommended practices. Traditional style geology literature is written The "ago" is implied, so that any such year number "X M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cancer (constellation)
Cancer is one of the twelve constellations of the zodiac and is located in the Northern celestial hemisphere. Its old astronomical symbol is (♋︎). Its name is Latin for crab and it is commonly represented as one. Cancer is a medium-size constellation with an area of 506 square degrees and its stars are rather faint, its brightest star Beta Cancri having an apparent magnitude of 3.5. It contains two stars with known planets, including 55 Cancri, which has five: one super-earth and four gas giants, one of which is in the habitable zone and as such has expected temperatures similar to Earth. At the (angular) heart of this sector of our celestial sphere is Praesepe (Messier 44), one of the closest open clusters to Earth and a popular target for amateur astronomers. Characteristics Cancer is a medium-sized constellation that is bordered by Gemini to the west, Lynx to the north, Leo Minor to the northeast, Leo to the east, Hydra to the south, and Canis Minor to the south ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harvard University
Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher learning in the United States and one of the most prestigious and highly ranked universities in the world. The university is composed of ten academic faculties plus Harvard Radcliffe Institute. The Faculty of Arts and Sciences offers study in a wide range of undergraduate and graduate academic disciplines, and other faculties offer only graduate degrees, including professional degrees. Harvard has three main campuses: the Cambridge campus centered on Harvard Yard; an adjoining campus immediately across Charles River in the Allston neighborhood of Boston; and the medical campus in Boston's Longwood Medical Area. Harvard's endowment is valued at $50.9 billion, making it the wealthiest academic institution in the world. Endo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
