Wikipedia

Virgo Supercluster

TheLocal Supercluster(LSCorLS) is a formerly defined supercluster containing theVirgo ClusterandLocal Group,which itself contains theMilky WayandAndromedagalaxies, as well as others. At least 100galaxy groupsandclustersare located within its diameter of 33megaparsecs(110 millionlight-years). The Virgo SC is one of about 10 millionsuperclustersin theobservable universeand is in thePisces–Cetus Supercluster Complex,agalaxy filament.

Local Supercluster
Distances from theLocal Groupfor selected groups and clusters within the Local Supercluster
Observation data (EpochJ2000)
Parent structureLaniakea Supercluster
RedshiftDoppler shift
Binding mass~1.48 × 1015[1]M☉
Luminosity(specify)3×1012L☉[1](total)
Other designations
Virgo Supercluster (old), LSC, LS

A 2014 study indicates that the Local Supercluster is only a part of an even greater supercluster,Laniakea,a larger group centered on theGreat Attractor,[2]thus subsuming the former Virgo Supercluster under Laniakea.

Background

edit

Beginning with the first large sample ofnebulaepublished byWilliamandJohn Herschelin 1863, it was known that there is a marked excess of nebular fields in the constellationVirgo,near the northgalactic pole.In the 1950s, French–American astronomerGérard de Vaucouleurswas the first to argue that this excess represented a large-scale galaxy-like structure, coining the term "Local Supergalaxy" in 1953, which he changed to "Local Supercluster" (LSC[3]) in 1958.Harlow Shapley,in his 1959 bookOf Stars and Men,suggested the termMetagalaxy.[4]

Debate went on during the 1960s and 1970s as to whether the Local Supercluster (LS) was actually a structure or a chance alignment of galaxies.[5] The issue was resolved with the large redshift surveys of the late 1970s and early 1980s, which convincingly showed the flattened concentration of galaxies along the supergalactic plane.[6]

Structure

edit

In a comprehensive 1982 paper,R. Brent Tullypresented the conclusions of his research concerning the basic structure of the LS. It consists of two components: an appreciably flattened disk containing two thirds of the supercluster's luminous galaxies, and a roughly spherical halo containing the remaining third.[7] The disk itself is a thin (~1Mpc) ellipsoid with a long axis / short axis ratio of at least 6 to 1, and possibly as high as 9 to 1.[8] Data released in June 2003 from the 5-yearTwo-degree-Field Galaxy Redshift Survey (2dF)has allowed astronomers to compare the LS to other superclusters. The LS represents a typical poor (that is, lacking a high density core) supercluster of rather small size. It has one rich galaxy cluster in the center, surrounded by filaments of galaxies and poor groups.[1]

TheLocal Groupis located on the outskirts of the LS in a small filament extending from theFornax Clusterto theVirgo Cluster.[6]The Virgo Supercluster's volume is roughly 7,000 times that of the Local Group, or 100 billion times that of the Milky Way.

Galaxy distribution

edit

Thenumber densityof galaxies in the LS falls off with the square of the distance from its center near theVirgo Cluster,suggesting that this cluster is not randomly located. Overall, the vast majority of the luminous galaxies (less thanabsolute magnitude−13) are concentrated in a small number ofclouds(groups ofgalaxy clusters). Ninety-eight percent can be found in the following 11 clouds, given in decreasing order of number of luminous galaxies:Canes Venatici,Virgo Cluster,Virgo II(southern extension),Leo II,Virgo III,Crater (NGC 3672),Leo I,Leo Minor (NGC 2841), Draco (NGC 5907), Antlia (NGC 2997), andNGC 5643.

Of the luminous galaxies located in the disk, one third are in the Virgo Cluster. The remainder are found in the Canes Venatici Cloud and Virgo II Cloud, plus the somewhat insignificantNGC 5643 Group.

The luminous galaxies in the halo are concentrated in a small number of clouds (94% in 7 clouds). This distribution indicates that "most of the volume of the supergalactic plane is a great void."[8]A helpful analogy that matches the observed distribution is that of soap bubbles. Flattish clusters andsuperclustersare found at the intersection of bubbles, which are large, roughly spherical (on the order of 20–60Mpcin diameter) voids in space.[9] Long filamentary structures seem to predominate. An example of this is theHydra–Centaurus Supercluster,the nearest supercluster to the Virgo Supercluster, which starts at a distance of roughly 30 Mpc and extends to 60 Mpc.[10]

Cosmology

edit

Large-scale dynamics

edit

Since the late 1980s it has been apparent that not only theLocal Group,but all matter out to a distance of at least 50Mpcis experiencing a bulk flow on the order of 600 km/s in the direction of theNorma Cluster (Abell 3627).[11] Lynden-Bell et al. (1988) dubbed the cause of this the "Great Attractor".The Great Attractor is now understood to be the center of mass of an even larger structure of galaxy clusters, dubbed"Laniakea",which includes the Virgo Supercluster (including the Local Group) as well as the Hydra-Centaurus Supercluster, the Pavo-Indus Supercluster, and the Fornax Group.

The Great Attractor, together with the entire supercluster, is found to be moving towardShapley Supercluster,with center ofShapley Attractor.[12]

Dark matter

edit

The LS has a total massM≈ 1015M☉and a total optical luminosityL≈ 3×1012L☉.[1]This yields amass-to-light ratioof about 300 times that of the solar ratio (M☉/L☉= 1), a figure that is consistent with results obtained for other superclusters.[13][14] By comparison, themass-to-light ratiofor theMilky Wayis 63.8 assuming a solarabsolute magnitudeof 4.83,[15]a Milky Way absolute magnitude of −20.9,[16] and a Milky Way mass of 1.25×1012M☉.[17]These ratios are one of the main arguments in favor of the presence of large amounts ofdark matterin the universe; if dark matter did not exist, much smaller mass-to-light ratios would be expected.

Maps

edit
Virgo ClusterCentaurus A/M83 GroupM81 groupMaffei GroupNGC 1023 GroupM101 groupNGC 2997 GroupCanes Venatici I GroupNGC 5033 groupUrsa Major ClusterLeo I GroupNGC 6744 GroupDorado GroupVirgo III GroupsNGC 4697Leo II GroupsNGC 7582Fornax ClusterEridanus ClusterLocal GroupSculptor Group
Map of the nearby universe within 100 million light-years from Earth, including a portion of theSouthern Superclusterat the bottom left and the Virgo Supercluster on the right insupergalactic coordinates(click on feature names for more information)
NGC 55Milky WayLarge Magellanic CloudNGC 3109Messier 31Messier 33NGC 247Circinus GalaxyNGC 5128NGC 5253NGC 5102NGC 5128 GroupIC 4662Messier 83Virgo ClusterESO 274-01NGC 1313NGC 625NGC 7793NGC 4945NGC 45NGC 253Sculptor GroupLocal GroupNGC 1569NGC 300IC 342Maffei GroupNGC 404NGC 784Maffei IMaffei IIDwingeloo 1NGC 1560Messier 81IC 2574Messier 82NGC 3077NGC 2976NGC 4605NGC 6503NGC 5204NGC 3738NGC 4236NGC 2366NGC 2403NGC 4305NGC 5023Messier 94NGC 4244NGC 4214NGC 4449NGC 4395Canes I GroupM81 Group
The nearest galaxy groups projected onto thesupergalactic plane(click on feature names for more information)

Diagrams

edit
A diagram of our location in theobservable universe.(Alternative image.)

See also

edit

References

edit
  1. ^abcd Einasto, M.; et al. (December 2007). "The richest superclusters. I. Morphology".Astronomy and Astrophysics.476(2): 697–711.arXiv:0706.1122.Bibcode:2007A&A...476..697E.doi:10.1051/0004-6361:20078037.S2CID15004251.
  2. ^R. Brent Tully;Hélène Courtois;Yehuda Hoffman; Daniel Pomarède (2 September 2014). "The Laniakea supercluster of galaxies".Nature.513(7516) (published 4 September 2014): 71–73.arXiv:1409.0880.Bibcode:2014Natur.513...71T.doi:10.1038/nature13674.PMID25186900.S2CID205240232.
  3. ^ cfa.harvard.edu,The Geometry of the Local Supercluster,John P. Huchra, 2007 (accessed 12-12-2008)
  4. ^Shapley, HarlowOf Stars and Men(1959)
  5. ^ de Vaucouleurs, G. (March 1981). "The Local Supercluster of Galaxies".Bulletin of the Astronomical Society of India.9:6 (see note).Bibcode:1981BASI....9....1D.
  6. ^ab Klypin, Anatoly; et al. (October 2003). "Constrained Simulations of the Real Universe: The Local Supercluster".The Astrophysical Journal.596(1): 19–33.arXiv:astro-ph/0107104.Bibcode:2003ApJ...596...19K.doi:10.1086/377574.S2CID1830859.
  7. ^ Hu, F. X.; et al. (April 2006). "Orientation of Galaxies in the Local Supercluster: A Review".Astrophysics and Space Science.302(1–4): 43–59.arXiv:astro-ph/0508669.Bibcode:2006Ap&SS.302...43H.doi:10.1007/s10509-005-9006-7.S2CID18837475.
  8. ^ab Tully, R. B. (15 Jun 1982)."The Local Supercluster".Astrophysical Journal.257(1): 389–422.Bibcode:1982ApJ...257..389T.doi:10.1086/159999.
  9. ^ Carroll, Bradley; Ostlie, Dale (1996).An Introduction to Modern Astrophysics.New York:Addison-Wesley.p. 1136.ISBN0-201-54730-9.
  10. ^ Fairall, A. P.; Vettolani, G.; Chincarini, G. (May 1989). "A wide angle redshift survey of the Hydra-Centaurus region".Astronomy and Astrophysics Supplement Series.78(2): 270.Bibcode:1989A&AS...78..269F.ISSN0365-0138.
  11. ^ Plionis, Manolis; Valdarnini, Riccardo (March 1991)."Evidence for large-scale structure on scales about 300/h MPC".Monthly Notices of the Royal Astronomical Society.249:46–61.Bibcode:1991MNRAS.249...46P.doi:10.1093/mnras/249.1.46.
  12. ^"What is the Great Attractor?".14 July 2014.
  13. ^ Small, Todd A.; et al. (Jan 1998). "The Norris Survey of the Corona Borealis Supercluster. III. Structure and Mass of the Supercluster".Astrophysical Journal.492(1): 45–56.arXiv:astro-ph/9708153.Bibcode:1998ApJ...492...45S.doi:10.1086/305037.S2CID119451873.
  14. ^ Heymans, Catherine; et al. (April 2008)."The dark matter environment of the A901 abell A901/902 supercluster: a weak lensing analysis of the HST STAGES survey".Monthly Notices of the Royal Astronomical Society.385(3): 1431–1442.arXiv:0801.1156.Bibcode:2008MNRAS.385.1431H.doi:10.1111/j.1365-2966.2008.12919.x.S2CID59057342.
  15. ^ Williams, D. R. (2004)."Sun Fact Sheet".NASA.Retrieved2012-03-17.
  16. ^Jerry Coffey."Absolute Magnitude".Retrieved2010-04-09.
  17. ^McMillan, Paul J. (July 2011), "Mass models of the Milky Way",Monthly Notices of the Royal Astronomical Society,414(3): 2446–2457,arXiv:1102.4340,Bibcode:2011MNRAS.414.2446M,doi:10.1111/j.1365-2966.2011.18564.x,S2CID119100616

Further reading

edit
edit
  • The Atlas of the Universe,a website created by astrophysicist Richard Powell that shows maps of our local universe on a number of different scales (similar to above maps).
Retrieved from "https://en.wikipedia.org/w/index.php?title=Virgo_Supercluster&oldid=1255224073"