View source for Astronomy:Shapley Supercluster

{{short description|Largest concentration of galaxies in our local universe}}
{{Infobox galaxy cluster
| name = Shapley Supercluster
| image =Galaxies_in_the_Shapley_Supercluster_-_Flickr_-_geckzilla.png
| image_size =
| caption =Galaxies in the Shapley Supercluster
| credit = 
| epoch = [[Astronomy:Epoch#Julian years and J2000|J2000]]
| constellation = [[Astronomy:Centaurus|Centaurus]]
| dec = {{DEC|-30|0|0}}<ref name="Proust, Quintana, Carrasco, Reisenegger et al, 2006"/>
| brightest_member = 
| member_no = 
| major_axis_mpc = <!-- {{cvt|000|Mpc|Mly|0|lk=on}} {{hub|0.00}} -->
| minor_axis_mpc = <!-- {{cvt|000|Mpc|Mly|0|lk=on}} {{hub|0.00}} -->
| redshift = 
| distance = {{cvt|200|Mpc|Mly|0|lk=on}}
| mass = <!-- 0{{e|14}} {{hub|0.00}}{{Solar mass|link=y|}} -->
| luminosity = 
| flux = 
| other_names = Shapley Concentration, SCl 124
}}
The '''Shapley Supercluster''' or '''Shapley Concentration''' ('''SCl 124''') is the largest concentration of galaxies in our nearby [[Astronomy:Universe|universe]] that forms a gravitationally interacting unit, thereby pulling itself together instead of expanding with the universe. It appears as a striking overdensity in the distribution of galaxies in the [[Astronomy:Constellation|constellation]] of [[Astronomy:Centaurus|Centaurus]]. It is 650 million [[Astronomy:Light-year|light-year]]s away ([[Astronomy:Redshift|z=0.046]]).

== History ==
In 1930,<ref>{{Cite web|title=The Shapley Supercluster|url=http://www.atlasoftheuniverse.com/superc/shapley.html|access-date=2020-09-23|website=www.atlasoftheuniverse.com}}</ref> Harlow Shapley and his colleagues at the [[Organization:Harvard College Observatory|Harvard College Observatory]] started a survey of galaxies in the southern sky, using photographic plates obtained at the 24-inch [[Biology:Boyden Observatory#Former telescopes|Bruce telescope]] at [[Place:Bloemfontein|Bloemfontein]], South Africa. By 1932, Shapley reported the discovery of 76,000 galaxies brighter than 18th [[Astronomy:Apparent magnitude|apparent magnitude]] in a third of the southern sky, based on galaxy counts from his plates. Some of this data was later published as part of the Harvard galaxy counts, intended to map galactic obscuration and to find the space density of galaxies.

In this catalog, Shapley could see most of the 'Coma-Virgo cloud' (now known to be a superposition of the [[Astronomy:Coma Supercluster|Coma Supercluster]] and the [[Astronomy:Virgo Supercluster|Virgo Supercluster]]), but found a 'cloud' in the constellation of [[Astronomy:Centaurus|Centaurus]] to be the most striking concentration of galaxies. He found it particularly interesting because of its "great linear dimension, the numerous population and distinctly elongated form". This can be identified with what we now know as the core of the Shapley [[Astronomy:Supercluster|Supercluster]]. Shapley estimated the distance to this cloud to be 14 times that to the [[Astronomy:Virgo Cluster|Virgo Cluster]], from the average diameters of the galaxies. This would place the Shapley Supercluster at a distance of 231 Mpc, based on the current estimate of the distance to Virgo.

In recent times, the Shapley Supercluster was named by Somak Raychaudhury,<ref>{{Cite journal |last=Raychaudhury |first=Somak |date=November 1989 |title=The distribution of galaxies in the direction of the 'Great Attractor' |url=https://www.nature.com/articles/342251a0 |journal=Nature |language=en-us |volume=342 |issue=6247 |pages=251–255 |doi=10.1038/342251a0 |bibcode=1989Natur.342..251R |s2cid=4354365 |issn=1476-4687}} 
</ref> from a survey of galaxies from [[Astronomy:UK Schmidt Telescope|UK Schmidt Telescope]] Sky survey plates, using the [[Organization:Institute of Astronomy, Cambridge#Achievements|Automated Plate Measuring Facility (APM)]] at the [[Organization:University of Cambridge|University of Cambridge]] in England. In this paper, the supercluster was named after Harlow Shapley, in recognition of his pioneering survey of galaxies in which this concentration of galaxies was first seen. Around the same time, Roberto Scaramella and co-workers had also noticed the Shapley Supercluster in the [[Astronomy:Abell catalogue|Abell catalogue]] of clusters of galaxies: they had named it the ''Alpha concentration''.<ref>{{Cite journal |last1=Scaramella |first1=R. |last2=Baiesi-Pillastrini |first2=G. |last3=Chincarini |first3=G. |last4=Vettolani |first4=G. |last5=Zamorani |first5=G. |date=April 1989 |title=A marked concentration of galaxy clusters: is this the origin of large-scale motions? |url=https://www.nature.com/articles/338562a0 |journal=Nature |language=en-us |volume=338 |issue=6216 |pages=562–564 |doi=10.1038/338562a0 |bibcode=1989Natur.338..562S |s2cid=4336689 |issn=1476-4687}}</ref>
[[File:Shapley.gif|thumb|upright=2.4|A map of the Shapley Supercluster]]

== Current interest ==
The Shapley Supercluster lies very close to the direction in which the [[Astronomy:Local Group|Local Group]] of galaxies (including our galaxy) is moving with respect to the [[Astronomy:Cosmic microwave background|cosmic microwave background]] (CMB) frame of reference. This has led many to speculate that the Shapley Supercluster may be one of the major causes of our galaxy's peculiar motion—the [[Astronomy:Great Attractor|Great Attractor]] may be another—and has led to a surge of interest in this supercluster. It has been found that the Great Attractor and all the galaxies in our region of the universe (including our galaxy, the [[Astronomy:Milky Way|Milky Way]]) are moving toward the Shapley Supercluster.<ref>{{Cite web|url=http://www.universetoday.com/113150/what-is-the-great-attractor/|title = What is the Great Attractor?|date = 14 July 2014}}</ref>

In 2017 it was proposed that the movement towards attractors like the [[Astronomy:Shapley Attractor|Shapley Attractor]] in the supercluster creates a relative movement away from underdense areas, that may be visualized as a virtual ''repeller''. This approach enables new ways of understanding and modelling variations in galactic movements. The nearest large underdense area has been labelled the [[Astronomy:Dipole repeller|dipole repeller]].<ref name="Hoffman2017">
{{cite journal|last1=Hoffman|first1=Yehuda|last2=Pomarède|first2=Daniel|last3=Tully|first3=R. Brent|last4=Courtois|first4=Hélène M.|author-link4=Hélène Courtois|date=30 January 2017|title=The dipole repeller|journal=Nature Astronomy|volume=1|issue=2|pages=0036|arxiv=1702.02483|bibcode=2017NatAs...1E..36H|doi=10.1038/s41550-016-0036|s2cid=7537393}}
</ref>

==See also==
* {{annotated link|Astronomy:Dark flow}}
* {{annotated link|Astronomy:Great Attractor}}
* {{annotated link|Astronomy:Hydra–Centaurus Supercluster}}
* {{annotated link|Astronomy:Norma Cluster}}
* {{annotated link|Astronomy:Supercluster}}

==References==
{{reflist}}

==External links==
* [http://www.atlasoftheuniverse.com/superc/shapley.html Shapley Supercluster] at Atlas of the Universe
* {{cite web |url= http://www.ira.inaf.it/~tventuri/shapley.html <!-- original: http://www.ira.cnr.it/~tventuri/shapley.html --> <!-- alternative: http://www.cnr.it/istituti/ProdottoDellaRicerca.html?cds=065&id=5893 --> |title= The Shapley Concentration |url-status= live |archive-date= March 26, 2007 |archive-url= https://web.archive.org/web/20070326003801/http://www.ira.cnr.it/~tventuri/shapley.html |display-authors= 0 |first1= Tiziana |last1= Venturi |first2= Sandro |last2= Bardelli |first3= Raffaella |last3= Morganti |first4= Richard W. |last4= Hunstead |publisher= Istituto di Radioastronomia (IRA) |website= Consiglio Nazionale delle Ricerche (CNR) }}
* [http://www.cfa.harvard.edu/hco/ Harvard College Observatory (HCO) ]
* {{cite web |url=http://www.ifa.hawaii.edu/info/press-releases/kocevski-1-06/ |title=X-rays Reveal What Makes the Milky Way Move |publisher=IFA |website=University of Hawaii |date=January 11, 2006 |quote=Part of Abell 3558, the galaxy cluster at the center of the Shapley Supercluster, the largest mass concentration in the observable Universe}}
* {{cite web |url= http://www.na.astro.it/ACCESS/ |title= A Complete CEnsus of Star formation in the Shapley supercluster |website= Istituto Nazionale di Astrofisica |publisher= Osservatorio Astronomico di Capodimonte }}
* {{cite journal |journal=Nature Astronomy |volume=1 |issue=36 |pages=0036 |title=Dipole Repeller |first1=Yehuda |last1=Hoffman |first2=Daniel |last2=Pomarède |first3=R. Brent |last3=Tully |first4=Hélène M. |author-link4=Hélène Courtois |last4=Courtois |doi=10.1038/s41550-016-0036 |date=Jan 30, 2017 |arxiv=1702.02483 |bibcode=2017NatAs...1E..36H |s2cid=7537393}}

{{Sky|13|25|0|-|30|0|0|652000000}}
{{Centaurus}}

{{DEFAULTSORT:Shapley Supercluster}}
[[Category:Shapley Supercluster| ]]
[[Category:Great Attractor]]
[[Category:Galaxy superclusters]]

{{Sourceattribution|Shapley Supercluster}}