Clusters of galaxies are often dominated by a single giant elliptical galaxy, known as the brightest cluster galaxy, which, over time, tidally destroys its satellite galaxies and adds their mass to its own.

Clusters of galaxies have been found in surveys by a number of observational techniques and have been studied in detail using many methods:

* Gravitational lensing: Clusters of galaxies contain enough matter to distort the observed orientations of galaxies behind them.

Clusters have two important properties: their masses are large enough to retain any energetic gas ejected from member galaxies and the thermal energy of the gas within the cluster is observable within the X-Ray bandpass.

Among these, the Book of Fixed Stars ( 964 ) was written by the Persian astronomer Abd al-Rahman al-Sufi, who observed a number of stars, star clusters ( including the Omicron Velorum and Brocchi's Clusters ) and galaxies ( including the Andromeda Galaxy ).

Clusters of galaxies should not be confused with star clusters such as galactic clusters and open clusters, which are structures within galaxies, as well as globular clusters, which typically orbit galaxies.

It also includes galaxies smaller than 1. 0 arcminute in diameter but brighter than 14. 5 magnitude from the Catalogue of Galaxies and of Clusters of Galaxies ( CGCG ).

A recent preliminary finding is that it can explain structure formation without CDM, but requiring a ~ 2eV massive neutrino ( They are also required to fit some Clusters of galaxies, including Bullet Cluster ) and.

* Clusters of galaxies

Clusters are not a syntactic language construct, but rather a standard organizational convention.

Clusters are then formed relatively recently between 10 billion years ago and now.

Clusters are larger than groups, although there is no sharp dividing line between the two.

Clusters are quite prominent in X-ray surveys and along with AGN are the brightest X-ray emitting extragalactic objects.

Clusters such as the Pleiades, Hyades and a few others within about 500 light years are close enough for this method to be viable, and results from the Hipparcos position-measuring satellite yielded accurate distances for several clusters.

Clusters are also a crucial step in determining the distance scale of the universe.

He waited until 1802 ( in Catalogue of 500 new Nebulae, nebulous Stars, planetary Nebulae, and Clusters of Stars ; with Remarks on the Construction of the Heavens ) to announce the hypothesis that the two stars might be " binary sidereal systems " orbiting under mutual gravitational attraction, a hypothesis he confirmed in 1803 in his Account of the Changes that have happened, during the last Twenty-five Years, in the relative Situation of Double-stars ; with an Investigation of the Cause to which they are owing.

* In J. K. Rowling's Harry Potter series, two kinds of sweets seen eaten by the characters are Chocolate Frogs and Cockroach Clusters.

; EUREKA Clusters are:

Clusters and large complexes of dark nebulae are associated with Giant Molecular Clouds.

Clusters of ' Black Corinth ' are small, averaging, ranging from 0. 2 to 0. 6 pounds.

Clusters of homes around old Lower Kula Road are becoming denser.

Clusters in Georgian of four, five or six consonants are not unusual — for instance, ( flat ), ( trainer ) and ( peeling )— and if grammatical affixes are used, it allows an eight-consonant cluster: ( he's plucking us ).

Clusters are made of two or more consonant sounds, while a digraph is a group of two consonant letters standing for a single sound.

Clusters of chard seeds are usually sown between April and August, depending on the desired harvesting period.

The University of Kiel helped develop this radiation detector for a Mars probe. Interdisciplinary research and a university-wide infrastructure are complemented by an array of research programs that are not included in the Excellence Clusters and collaborative research centers.

His major contribution was the monumental New General Catalogue of Nebulae and Clusters of Stars ( based on William Herschels Catalogue of Nebulae ), the catalogue numbers of which are still in use, as well as two supplementary Index Catalogues.

It offers the most comprehensive monitoring from Oracle Database instances to Oracle Real Application Clusters to Oracle Application Server Farms and Clusters.

Herschel's discoveries were supplemented by those of Caroline Herschel ( 11 objects ) and his son John Herschel ( 1754 objects ) and published by him as General Catalogue of Nebulae and Clusters in 1864.

The New General Catalogue of Nebulae and Clusters of Stars ( abbreviated as NGC ) is a well-known catalogue of deep sky objects in astronomy compiled by John Louis Emil Dreyer in 1888, as a new version of John Herschel's Catalogue of Nebulae and Clusters of Stars.

Dreyer had already published a supplement to Herschel's General Catalogue of Nebulae and Clusters ( GC ), containing about 1, 000 new objects.

The first major update to the NGC is the Index Catalogue of Nebulae and Clusters of Stars ( abbreviated as IC ), published in two parts by Dreyer in 1895 ( IC I, containing 1, 520 objects ) and 1908 ( IC II, containing 3, 866 objects ).

* New General Catalogue of Nebulae and Clusters of Stars, a catalogue of deep sky objects in astronomy

Clusters correspond generally to the concept of an " object " in an OO language, and have roughly the same syntax.

Clusters which have enough mass to be gravitationally bound once the surrounding nebula has evaporated can remain distinct for many tens of millions of years, but over time internal and external processes tend also to disperse them.

Clusters of patients with Chuvash polycythemia have been found in other populations, such as on the Italian island of Ischia, located in the Bay of Naples.

The 1997 Catalogue of Variable Stars in Globular Clusters listed 28 candidate variable stars in the cluster, although only 20 have been confirmed.

Clusters containing zero-metallicity red dwarfs or brown dwarfs ( possibly created by pair-instability supernovae ) have been proposed as dark matter candidates ,, but searches for these and other MACHO's through gravitational microlensing have produced negative results.

Clusters of Excellence have been conceived to contribute importantly to the respective university ’ s strategic planning and to accelerate the process of setting thematic priorities at universities.

* International Association for Suicide Prevention ( IASP )-Special Interest Group-Clusters and Contagion in Suicidal Behaviour ( Aim of the IASP Special Interest Group ( SIG ) on Clusters and Contagion in Suicidal Behaviour is to bring together interested people in research, prevention and policy, who can share information and expertise in clusters and contagion effects in suicidal behaviour worldwide ).

* Super Star Clusters, in astronomy, possible progenitors of globular clusters

Quadrics was selected by HP for the upgrade of SHARCNET, the Canadian Cluster of Clusters, with four new high-performance computing clusters that would increase the network's capacity from 1, 000 to 6, 000 processors.

QsNet is a high speed interconnect designed by Quadrics used in HPC clusters, particularly Linux Beowulf Clusters.

The Catalogue of Galaxies and of Clusters of Galaxies ( pr CGCG ) was compiled by Fritz Zwicky in 1961 – 68, and contains 9134 galaxy clusters.

High availability clusters ( HAC ) improve application availability by failing them over or switching them over in a group of systems — as opposed to High Performance Clusters, which improve application performance by running them on multiple systems simultaneously.