supercluster: Definition from Answers.com

This article is about astronomy. For other uses, see Supercluster (disambiguation).

A map of the nearest (to Virgo) Superclusters

Superclusters are large groups of smaller galaxy groups and clusters and are among the largest structures of the cosmos.

Existence

The existence of superclusters indicates that the galaxies in our Universe are not uniformly distributed; most of them are drawn together in groups and clusters, with groups containing up to 50 galaxies and clusters up to several thousand. Those groups and clusters and additional isolated galaxies in turn form even larger structures called superclusters.

Once thought to be the largest structures in nature, superclusters are now understood to be subordinate to enormous walls or sheets, usually called "filaments", sometimes called "super cluster complexes", "walls" or "sheets", that can span a billion light-years in length, more than 5% of the observable universe. Super clusters themselves can span several hundred million light-years. The typical speed of a galaxy is about 1000 km/s. Hubble's law implies that typical galaxies would only move about 30 million light-years at that speed in a Hubble time of 1/H, which is approximately the age of the universe. While this is a huge distance in human terms, it is much smaller than the size of super clusters. In an expanding universe, saying that the distance d an object has moved equals its present velocity v times the elapsed time t underestimates d when t is not small compared to 1/H. The calculation above still gives some idea of how long it would take the normal movements of galaxies to form or obliterate these structures, and thus indicates their great age. When we observe super clusters and larger structures today, we learn about the condition of the universe when these super clusters were created. The directions of the rotational axes of galaxies within super clusters also gives us insight into the formation process of galaxies early in the history of the Universe.^[1]

According to some astronomers, no clusters of super clusters (“hyperclusters”) are known; the existence of structures larger than superclusters is debated (see Galaxy filament). Interspersed among super clusters are large voids of space in which few galaxies exist. Even though superclusters are the largest structures confirmed, the total number of superclusters leaves possibilities for structural distribution; the total number of super clusters in the universe is believed to be close to 10 million.

Super clusters are frequently subdivided into groups of clusters called galaxy clouds.

List of superclusters

Nearby superclusters

Galaxy supercluster	Data	Notes
Local Supercluster	z=0.000 (0 light years away) Length = 33 Mpc (110 million light years)	It contains the Local Group with our galaxy, the Milky Way. It also contains the Virgo cluster near its center, and is sometimes called the Virgo Supercluster.
Hydra-Centaurus Supercluster		It is composed of two lobes, sometimes also referred to as superclusters, or sometimes the entire supercluster is referred to by these other two names Hydra Supercluster Centaurus Supercluster
Perseus-Pisces Supercluster
Pavo-Indus Supercluster
Coma Supercluster		Forms most of the CfA Homunculus, the center of the CfA2 Great Wall galaxy filament
Phoenix Supercluster
Sculptor Superclusters		SCl 9
Hercules Superclusters		SCl 160
Leo Supercluster		SCl 93
Ophiucus Supercluster	17^h 10^m -22° cz=8500-9000 km/s (centre) 18 Mpc x 26 Mpc	Forming the far wall of the Ophiucus Void, it may be connected in a filament, with the Pavo-Indus-Telescopium Supercluster and the Hercules Supercluster. This supercluster is centered on the cD cluster Ophiucus Cluster, and has at least two more galaxy clusters, four more galaxy groups, several field galaxies, as members.^[2]
Shapley Supercluster		The second supercluster found, after the Local Supercluster.

Distant superclusters

Galaxy supercluster	Data	Notes
Pisces-Cetus Supercluster
Bootes Supercluster		SCl 138
Horologium Supercluster	z=0.063 (700 Mly) Length = 550 Mly	The entire supercluster is referred to as the Horologium-Reticulum Supercluster
Corona Borealis Supercluster
Columba Supercluster
Aquarius Supercluster
Aquarius B Supercluster
Aquarius-Capricornus Supercluster
Aquarius-Cetus Supercluster
Bootes A Supercluster
Caelum Supercluster		SCl 59
Draco Supercluster
Draco-Ursa Major Supercluster
Fornax-Eridanus Supercluster
Grus Supercluster
Leo A Supercluster
Leo-Sextans Supercluster
Leo-Virgo Supercluster		SCl 107
Microscopium Supercluster		SCl 174
Pegasus-Pisces Supercluster		SCl 3
Pisces Supercluster		SCl 24
Pisces-Aries Supercluster
Ursa Major Supercluster
Virgo-Coma Supercluster		SCl 111

Far distant superclusters

Galaxy supercluster	Data	Notes
Lynx Supercluster	z=1.27	Discovered in 1999^[3] (as ClG J0848+4453, a name now used to describe the western cluster, with ClG J0849+4452 being the eastern one),^[4] it contains at least two clusters RXJ 0848.9+4452 (z=1.26) and RXJ 0848.6+4453 (z=1.27) . At the time of discovery, it became the most distant known supecluster.^[5] Additionally, seven smaller groups of galaxies are associated with the supercluster.^[6]
SCL @ 1338+27 at z=1.1	z=1.1 Length=70Mpc	A rich supercluster with several galaxy clusters was discovered around an unusual concentration of 23 QSOs at z=1.1 in 2001. The size of the complex of clusters may indicate a wall of galaxies exists there, instead of a single supercluster. The size discovered approaches the size of the CfA2 Great Wall filament. At the time of the discovery, it was the largest and most distant supercluster beyond z=0.5 ^[7]^[8]
SCL @ 1604+43 at z=0.9	z=0.91	This supercluster at the time of its discovery was the largest supercluster found so deep into space, in 2000. It consisted of two known rich clusters and one newly discovered cluster as a result of the study that discovered it. The then known clusters were Cl 1604+4304 (z=0.897) and Cl 1604+4321 (z=0.924), which then known to have 21 and 42 known galaxies respectively. The then newly discovered cluster was located at 16^h 04^m 25.7^s, +43° 14′ 44.7″ ^[9]
SCL @ 0018+16 at z=0.54 in SA26	z=0.54	This supercluster lies around radio galaxy 54W084C (z=0.544) and is composed of at least three large clusters, CL 0016+16 (z=0.5455), RX J0018.3+1618 (z=0.5506), RX J0018.8+1602 .^[10]
MS 0302+17	z=0.42 Length=6Mpc	This supercluster has at least three member clusters, the eastern cluster CL 0303+1706, southern cluster MS 0302+1659 and northern cluster MS 0302+1717.^[11]

References

^ Hu, F. X.; Wu, G. X.; Song, G. X.; Yuan, Q. R.; Okamura, S. (2006). "Orientation of Galaxies in the Local Supercluster: A Review". Astrophysics and Space Science 302 (1-4): 43–59. doi:10.1007/s10509-005-9006-7. http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2006Ap%26SS.302...43H.
^ Hasegawa, Takashi; Wakamatsu, Ken-ichi; Malkan, Matthew; Sekiguchi, Kazuhiro; Menzies, John W.; Parker, Quentin A.; Jugaku, Jun; Karoji, Hiroshi; Okamura, Sadanori (2000) "Large-scale structure of galaxies in the Ophiuchus region" (PDF) Monthly Notices of the Royal Astronomical Society, Volume 316, Issue 2, pp. 326-344 Bibcode: 2000MNRAS.316..326H doi:10.1046/j.1365-8711.2000.03531.x
^ Piero Rosati et al (1999) "An X-Ray-Selected Galaxy Cluster at z = 1.26" The Astronomical Journal 118 76-85
^ SIMBAD, "Lynx Supercluster"
^ Fumiaki Nakata, Tadayuki Kodama, Kazuhiro Shimasaku, Mamoru Doi, Hisanori Furusawa, Masaru Hamabe, Masahiko Kimura, Yutaka Komiyama, Satoshi Miyazaki, Sadanori Okamura, Masami Ouchi, Maki Sekiguchi, Masafumi Yagi and Naoki Yasuda (2004) "Discovery of a large-scale clumpy structure of the Lynx supercluster at z∼1.27", (PDF) Proceedings IAU Colloquium No. 195, doi:10.1017/S1743921304000080
^ Kouji Ohta, Masayuki Akiyama, Yoshihiro Ueda, Toru Yamada, Kouichiro Nakanishi, Gavin B. Dalton, Yasushi Ogasaka, Tsuneo Kii, Kiyoshi Hayashida (2003) "Optical Identification of the ASCA Lynx Deep Survey: An Association of Quasi-Stellar Objects and a Supercluster at z = 1.3?" The Astrophysical Journal, 598:210-215
^ Ichi Tanaka (2004) "Subaru Observation of a Supercluster of Galaxies and QSOS at Z = 1.1" Studies of Galaxies in the Young Universe with New Generation Telescope, Proceedings of Japan-German Seminar, held in Sendai, Japan, July 24-28, 2001 Bibcode: 2004sgyu.conf...61T
^ Ichi Tanaka, Toru Yamada, Edwin L. Turner, Yasushi Suto (2000) "Superclustering of Faint Galaxies in the Field of a QSO Concentration at z ~ 1.1" The Astrophysical Journal, 547:521-530
^ Lori M. Lubin et al (2000) "A Definitive Optical Detection of a Supercluster at z~0.91" (PDF) The Astrophysical Journal, 531:L5–L8 doi:10.1086/312518
^ A. J. Connolly et al (1996) "Superclustering at Redshift z = 0.54" (PDF) The Astrophysical Journal, 473:L67–L70 doi:10.1086/310395
^ University of Hawaii, "The MS0302+17 Supercluster", Nick Kaiser. Retrieved 15 September 2009.

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