This page 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 even when they are much smaller than more distant clusters.
Clusters exhibiting strong evidence of dark matter
Some clusters exhibiting strong evidence of dark matter.
In this collision between two clusters of galaxies, the stars pass between each other unhindered, while the hot, diffuse gas experiences friction and is left behind between the clusters. The gas dominates the visible mass budget of the clusters, being several times more massive than all the stars. Yet the regions with the stars show more gravitational lensing than the gas region, indicating that they are more massive than the gas. Some dark (since we don't see it), collision-less (or it would have been slowed, like the gas) matter is inferred to be present to account for the extra lensing around otherwise low-mass regions.[2]
This is actually a collision between two galaxy clusters. The galaxies and the dark matter seems to have separated out into separate dark and light cores.[3]
Abell 2142
A collision between two massive, X-ray luminous galaxy clusters.
This is a recently coalesced merger of galaxy clusters, which has resulted in a ring of dark matter around the galaxies, yet to be redistributed.[4][5]
Named groups and clusters
This is a list of galaxy groups and clusters that are well known by something other than an entry in a catalog or list, or a set of coordinates, or a systematic designation.
The cluster is named for the merger of two clusters colliding like a bullet
Also has a systematic designation of 1E 0657-56
El Gordo
Named for its size, El Gordo ("the fat one") is the biggest cluster found in the distant universe (at its distance and beyond), at the time of discovery in 2011, with a mass of 3 quadrillion suns. Second most massive galaxy cluster next to El Gordo is RCS2 J2327, a galaxy cluster with the mass of 2 quadrillion suns.
Also has a systematic designation of ACT-CL J0102-4915.[6][7][8]
Musket Ball Cluster
Named in comparison to the Bullet Cluster, as this one is older and slower galaxy cluster merger than the Bullet Cluster.
Also has a systematic designation of DLSCL J0916.2+2951.[9]
Pandora's Cluster
Named because the cluster resulted from a collision of clusters, which resulted in many different and strange phenomena.
Named in comparison with the Bullet Cluster, being of similar formation, except smaller.
Also has a systematic catalogue name SL2S J08544-0121. As of 2014, it was the lowest mass object that showed separation between the concentrations of dark matter and baryonic matter in the object.[11][12]
Burbidge Chain
Copeland Septet
Discovered by British astronomer Ralph Copeland in 1874.
Deer Lick Group
Coined by Tom Lorenzin (author of "1000+ The Amateur Astronomers' Field Guide to Deep Sky Observing") to honor Deer Lick Gap in the mountains of North Carolina, from which he had especially fine views of the galaxy group.
Also referred to as the NGC 7331 Group, after the brightest member of the group.[13]
Named after its discoverer, Carl Seyfert. At the time it appeared to contain six external nebulae. It is also called the NGC 6027 Sextet, after its brightest member.
There are actually only five galaxies in the sextet, and only four galaxies in the compact group. One of the galaxies is an ungravitationally bound background object. The other "galaxy" is instead an extension of the interacting system — a tidal stream caused by the merger. The group is, therefore, more properly called HCG 79; the name refers to the visual collection and not the group. HCG 79 lies 190 million light-years away in the Serpens Caput constellation.
There are actually only four galaxies in the compact group, the other galaxy is a foreground galaxy. The group is therefore more properly called HCG 92, because the name refers to a visual collection and not a group. Thus, the real group is also called Stephan's Quartet
Wild's Triplet
Named after the British-born and Australia-based astronomer Paul Wild (1923–2008), who studied the trio in the early 1950s.[14]
Zwicky's Triplet
The major nearby groups and clusters are generally named after the constellation they lie in. Many groups are named after the leading galaxy in the group. This represents an ad hoc systematic naming system.
Groups and clusters visible to the unaided eye
The Local Group contains the largest number of visible galaxies with the naked eye. However, its galaxies are not visually grouped together in the sky, except for the two Magellanic Clouds. The IC342/Maffei Group, the nearest galaxy group, would be visible by the naked eye if it were not obscured by the stars and dust clouds in the Milky Way's spiral arms.
The Centaurus A galaxy has been spotted with the naked eye by Stephen James O'Meara [16][17] and M83 has also reportedly been seen with the naked eye.[18]
Our Galaxy, the Milky Way, belongs to the Local Group.
LGG 104 (IC 342/Maffei Group, IC 342 / Maffei 1 Group, IC 342 Maffei 1-2 Group)
0.000868
260
The IC 342/Maffei Group contains two subgroups, the IC 342 subgroup (IC 342 Group) and the Maffei 1 subgroup (Maffei subgroup, Maffei 1 Group, Maffei Group).
The Centaurus A/M83 Group contains two subgroups, the Centaurus A subgroup (Centaurus A Group, NGC 5128 Group, LGG 344) and the M83 subgroup (M83 Group, NGC 5236 Group, LGG 355).
Mly represents millions of light-years, a measure of distance.
Mpc represents millions of parsecs, a measure of distance (1 Mpc = 3.26 Mly).
z represents redshift, a measure of recessional velocity and inferred distance due to cosmological expansion. In this very nearby context, however, the observed redshift and recessional velocity are due to the Doppler shifting of the light.
Distances are measured from Earth, with Earth being at zero.
ClG 0848+4453 forms a double-cluster supercluster with RDCS J0849+4452 [42][43][44][45][46]
galaxy cluster around 3C 324 (3C 234 Cluster)
1984–
1.206
At the time, the BCG, 3C324 was the most distant non-quasar galaxy.[47]
Cl 1409+524
1960–1975
0.461
The measurement of 3C295's redshift in 1960 also defined its cluster's position. 3C 295 was also the most distant galaxy of the time.[48][49]
Abell 732 (fainter Hydra Cluster Cl 0855+0321)
1951–1960
0.2
61 000
Attempts at measuring the redshift of the brightest cluster galaxy of this Hydra Cluster had been attempted for years before it had been successfully achieved. The BCG was also the most distant galaxy of the time.[48][50][51][52]
Abell 1930 (Bootes Cluster)
1936–1951
0.13
39 000
The BCG of this cluster was also the most distant galaxy of the time.[51][53]
Gemini Cluster (Abell 568)
1932 − 1936
0.075
23 000
The BCG of this cluster was the most distant galaxy at the time.[53][54]
WH Christie's Leo Cluster
1931–1932
19 700
The BCG of this cluster was the most distant galaxy known at the time.[51][54][55][56][57]
Baede's Ursa Major Cluster
1930–1931
11 700
The BCG of this cluster was the highest redshift galaxy of the time.[57][58]
This cluster's distance was determined by one of the NGC objects lying in it, NGC4860.[58][59]
Pegasus Group (LGG 473, NGC 7619 Group)
1929
0.012
3 779
The BCG for this group was used to measure its redshift. Shortly after this was publicized, it was accepted that redshifts were an acceptable measure of inferred distance.[60]
Cetus Group (Holmberg 45, LGG 27)
1921–1929
0.006
1 800
NGC 584 (Dreyer 584) was measured for the redshift to this galaxy group.[60][61][62][63]
This was the first noted cluster of "nebulae" that would become galaxies. The first redshifts to galaxies in the cluster were measured in the 1910s. Galaxies were not identified as such until the 1920s. The distance to the Virgo Cluster would have to wait until the 1930s.[21]
Mly represents millions of light-years, a measure of distance.
Mpc represents millions of parsecs, a measure of distance.
z represents redshift, a measure of recessional velocity and inferred distance due to cosmological expansion.
Distances are measured from Earth, with Earth being at zero.
In 2003 RDCS 1252-29 (RDCS1252.9–2927) at z=1.237, was found to be the most distant rich cluster, which lasted until 2005.[38][40][42]
In 2000, a cluster was announced in the field of quasar QSO 1213-0017 at z=1.31 (the quasar lies at z=2.69) [64]
In 1999, cluster RDCS J0849+4452 (RX J0849+4452, RXJ0848.9+4452) was found at z=1.261 [43][46]
In 1995 and 2001, the cluster around 3C 294 was announced, at z=1.786 [65]
In 1992, observations of the field of cluster Cl 0939+4713 found what appears to be a background cluster near a quasar, also in the background. The quasar was measured at z=2.055 and it was assumed that the cluster would be as well.[66][67][68][69]
In 1975, 3C 123 and its galaxy cluster was incorrectly determined to lie at z=0.637 (actually z=0.218) [70][71]
In 1958, cluster Cl 0024+1654 and Cl 1447+2619 were estimated to have redshifts of z=0.29 and z=0.35 respectively. However, they were not spectroscopically determined.[48]
Farthest protoclusters
5 Farthest protoclusters
Galaxy protocluster
Distance
Notes
No entries yet
Mly represents millions of light-years, a measure of distance.
Mpc represents millions of parsecs, a measure of distance.
z represents redshift, a measure of recessional velocity and inferred distance due to cosmological expansion.
Distances are measured from Earth, with Earth being at zero.
z represents redshift, a measure of recessional velocity and inferred distance due to cosmological expansion.
Distances are measured from Earth, with Earth being at zero.
In 2002, a very large, very rich protocluster, or the most distant protosupercluster was found in the field of galaxy cluster MS 1512+36, around the gravitationally lensed galaxy MS 1512-cB58, at z=2.724 [77][79]
False clusters
Sometimes clusters are put forward that are not genuine clusters or superclusters. Through the researching of member positions, distances, peculiar velocities, and binding mass, former clusters are sometimes found to be the product of a chance line-of-sight superposition.
Former cluster
Notes
Cancer Cluster
The Cancer Cluster was found to be a random assortment of galaxy groups, and not a true cluster.[21]
Coma-Virgo Cloud
The early identification of the Coma-Virgo Cloud of Nebulae was actually a mistaken identification due to the superposition of the Virgo Supercluster and Coma Supercluster, and not a Coma-Virgo Supercluster
^Gastaldello, F.; et al. (2014). "Dark matter–baryons separation at the lowest mass scale: The Bullet Group". Monthly Notices of the Royal Astronomical Society: Letters. 442: L76–L80. arXiv:1404.5633. Bibcode:2014MNRAS.442L..76G. doi:10.1093/mnrasl/slu058.
^ abcBiviano, Andrea; et al. (2000). "From Messier to Abell: 200 years of science with galaxy clusters". In Florence Durret; Daniel Gerbal (eds.). Constructing the Universe with Clusters of Galaxies, IAP 2000 meeting, Paris, France, July 2000. Constructing the Universe with Clusters of Galaxies. p. 1. arXiv:astro-ph/0010409. Bibcode:2000cucg.confE...1B.
^ abMAX-PLANCK-INSTITUT FÜR EXTRATERRESTRISCHE PHYSIK, GARCHING, GERMANY ; DEPARTMENT OF ASTRONOMY, UNIVERSITY OF MICHIGAN, ANN ARBOR, USA ; ESO, ASTROPHYSIKALISCHES INSTITUT, POTSDAM, GERMANY ; "GALAXY CLUSTER ARCHAEOLOGY"(PDF). Archived from the original(PDF) on 2006-06-22. ; HANS BÖHRINGER, CHRISTOPHER MULIS, PIERO ROSATI, GEORG LAMER, RENE FASSBENDER, AXEL SCHWOPE, PETER SCHUECKER
^ abRosati, P.; et al. (2004). "ChandraandXMM-Newton Observations of RDCS 1252.9-2927, A Massive Cluster atz=1.24". The Astronomical Journal. 127: 230–238. arXiv:astro-ph/0309546. doi:10.1086/379857.
^ abStanford, S. A.; Holden, Brad; Rosati, Piero; Eisenhardt, Peter R.; Stern, Daniel; Squires, Gordon; Spinrad, Hyron (2002). "An X-Ray–Selected Galaxy Cluster at [ITAL][CLC]z[/CLC][/ITAL] = 1.11 in the [ITAL]ROSAT[/ITAL] Deep Cluster Survey". The Astronomical Journal. 123 (2): 619–626. arXiv:astro-ph/0110709. doi:10.1086/338442.
^Stanford, S. A.; et al. (2001). "The Intracluster Medium inz > 1 Galaxy Clusters". The Astrophysical Journal. 552 (2): 504–507. arXiv:astro-ph/0012250. doi:10.1086/320583.
^ abcSandage, Allan (1961). "The Ability of the 200-INCH Telescope to Discriminate Between Selected World Models". The Astrophysical Journal. 133: 355. Bibcode:1961ApJ...133..355S. doi:10.1086/147041.
^"1053 May 8 meeting of the Royal Astronomical Society". The Observatory. 73: 97. 1953. Bibcode:1953Obs....73...97.
^ abcAnnu. Rev. Astron. Astrophys. 1988. 26: 561-630 ; OBSERVATIONAL TESTS OF WORLD MODELS - 6. THE m(z) HUBBLE DIAGRAM ; Allan Sandage
^Merrill, Paul W. (1958). "From Atoms to Galaxies". Leaflet of the Astronomical Society of the Pacific. 7 (349): 393. Bibcode:1958ASPL....7..393M.
^ abHumason, M. L. (1936). "The Apparent Radial Velocities of 100 Extra-Galactic Nebulae". The Astrophysical Journal. 83: 10. Bibcode:1936ApJ....83...10H. doi:10.1086/143696.
^ abChant, C. A. (1932). "Notes and Queries (Doings at Mount Wilson-Ritchey's Photographic Telescope-Infra-red Photographic Plates)". Journal of the Royal Astronomical Society of Canada. 26: 180. Bibcode:1932JRASC..26..180C.
^Humason, Milton L. (1931). "Apparent Velocity-Shifts in the Spectra of Faint Nebulae". The Astrophysical Journal. 74: 35. Bibcode:1931ApJ....74...35H. doi:10.1086/143287.
^Hubble, Edwin; Humason, Milton L. (1931). "The Velocity-Distance Relation among Extra-Galactic Nebulae". The Astrophysical Journal. 74: 43. Bibcode:1931ApJ....74...43H. doi:10.1086/143323.
^ abHumason, M. L. (1931). "The Large Apparent Velocities of Extra-Galactic Nebulae". Leaflet of the Astronomical Society of the Pacific. 1 (37): 149. Bibcode:1931ASPL....1..149H.
^ abHumason, M. L. (1930). "The Rayton short-focus spectrographic objective". The Astrophysical Journal. 71: 351. Bibcode:1930ApJ....71..351H. doi:10.1086/143255.
^Liu, Michael C.; et al. (2000). "Extremely Red Objects in the Field of QSO 1213-0017: A Galaxy Concentration at Z=1.31". The Astronomical Journal. 119 (6): 2556–2570. arXiv:astro-ph/0002443. Bibcode:2000AJ....119.2556L. doi:10.1086/301399.
^Dressler, A. (1993). "The Spectra and Morphology of Galaxies in High-Redshift Clusters". Observational Cosmology. 51: 225. Bibcode:1993ASPC...51..225D.
^Dressler, Alan (1993). "Galaxies Far Away and Long Ago". Sky and Telescope. 85 (4): 22. Bibcode:1993S&T....85...22D.
^Dressler, Alan; Oemler, Augustus; Gunn, James E.; Butcher, Harvey (1993). "A Cluster of Nascent Galaxies at Z = 2?". The Astrophysical Journal. 404: L45. Bibcode:1993ApJ...404L..45D. doi:10.1086/186740.
^Spinrad, H. (1975). "3C 123: A distant first-ranked cluster galaxy at z = 0.637". The Astrophysical Journal. 199: L3. Bibcode:1975ApJ...199L...3S. doi:10.1086/181835.
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