The Local Supercluster (LSC or LS), or Virgo Supercluster is a formerly defined supercluster containing the

Virgo Cluster The Virgo Cluster is a cluster of galaxies whose center is 53.8 ± 0.3 Mly (16.5 ± 0.1 Mpc) away in the Virgo constellation. Comprising approximately 1,300 (and possibly up to 2,000) member galaxies, the cluster forms the heart of the larger ...

and

Local Group The Local Group is the galaxy group that includes the Milky Way, where Earth is located. It has a total diameter of roughly , and a total mass of the order of . It consists of two collections of galaxies in a " dumbbell" shape; the Milky Way ...

, which itself contains the

Milky Way The Milky Way or Milky Way Galaxy is the galaxy that includes the Solar System, with the name describing the #Appearance, galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galax ...

and Andromeda galaxies, as well as others. At least 100

galaxy group A galaxy group or group of galaxies (GrG) is an aggregation of galaxies comprising about 50 or fewer gravitationally bound members, each at least as luminous as the Milky Way (about 1010 times the luminosity of the Sun); collections of galaxi ...

s and

clusters may refer to: Science and technology Astronomy * Cluster (spacecraft), constellation of four European Space Agency spacecraft * Cluster II (spacecraft), a European Space Agency mission to study the magnetosphere * Asteroid cluster, a small ...

are located within its diameter of 33 megaparsecs (110 million

light-years A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astro ...

). The Virgo Supercluster is one of about 10 million

supercluster A supercluster is a large group of smaller galaxy clusters or galaxy groups; they are among the largest known structures in the universe. The Milky Way is part of the Local Group galaxy group (which contains more than 54 galaxies), which in tu ...

s in the

observable universe The observable universe is a Ball (mathematics), spherical region of the universe consisting of all matter that can be observation, observed from Earth; the electromagnetic radiation from these astronomical object, objects has had time to reach t ...

, with the main body of the supercluster, the Virgo Strand, connecting the Hydra-Centaurus and the Perseus–Pisces Superclusters. The Virgo Supercluster is part of the Pisces–Cetus Supercluster Complex, a

galaxy filament In cosmology, galaxy filaments are the largest known structures in the universe, consisting of walls of galactic superclusters. These massive, thread-like formations can commonly reach 50 to 80 megaparsecs ()—with the largest found to date b ...

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

Background

Beginning with the first large sample of

nebula A nebula (; or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral, or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regions, such as in the Pillars of Creation in ...

e published by

William William is a masculine given name of Germanic languages, Germanic origin. It became popular in England after the Norman Conquest, Norman conquest in 1066,All Things William"Meaning & Origin of the Name"/ref> and remained so throughout the Middle ...

and

John Herschel Sir John Frederick William Herschel, 1st Baronet (; 7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor and experimental photographer who invented the blueprint and did botanical work. ...

in 1863, it was known that there is a marked excess of nebular fields in the constellation

Virgo Virgo may refer to: Arts and entertainment * Virgo (film), a 1970 Egyptian film * Virgo (character), several Marvel Comics characters * Virgo Asmita, a character in the manga ''Saint Seiya: The Lost Canvas'' * ''Virgo'' (album), by Virgo Four, ...

, near the north galactic pole. In the 1950s, French–American astronomer Gérard de Vaucouleurs was 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) in 1958.

Harlow Shapley Harlow Shapley (November 2, 1885 – October 20, 1972) was an American astronomer, who served as head of the Harvard College Observatory from 1921–1952, and political activist during the latter New Deal and Fair Deal. Shapley used Cepheid var ...

, in his 1959 book ''Of Stars and Men'', suggested the term ''Metagalaxy''. 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. 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.

Structure

In 1982, R. Brent Tully presented 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. The disk itself is a thin (~1 Mpc) ellipsoid with a long axis / short axis ratio of at least 6 to 1, and possibly as high as 9 to 1. Data released in June 2003 from the 5-year Two-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. The

is located on the outskirts of the LS in a small filament extending from the

Fornax Cluster The Fornax Cluster is a cluster of galaxies lying at a distance of 19 megaparsecs (62 million light-years). It has an estimated mass of solar masses, making it the second richest galaxy cluster within 100 million light-years, after the consider ...

to the

. The Virgo Supercluster's volume is roughly 7,000 times that of the Local Group, or 100 billion times that of the Milky Way. The main body of the Virgo Supercluster, the flattened disk of galaxies is simply part of a larger

known as the Virgo Strand or Centaurus–Virgo–PP Filament. This filament emanates from the

Centaurus Cluster The Centaurus Cluster (A3526) is a cluster of hundreds of galaxies, located approximately 170 million light-years away in the Centaurus constellation. The brightest member galaxy is the elliptical galaxy NGC 4696 (~11m). The Centaurus clust ...

through the

and continues through the Ursa Major Cluster all the way to the

Perseus–Pisces Supercluster The Perseus–Pisces Supercluster (SCl 40) is one of the largest known structures in the universe. Even at a distance of 250 million light-years, this chain of galaxy clusters extends more than 40° across the northern winter sky. The Perseus– ...

. The Virgo Strand consists of two branches, an upper branch consisting of the main body of the supercluster though the Virgo Southern Extension, the

and the Ursa Major Cluster, and a lower branch consisting of the

Crater A crater is a landform consisting of a hole or depression (geology), depression on a planetary surface, usually caused either by an object hitting the surface, or by geological activity on the planet. A crater has classically been described ...

and Leo Clouds. The rest of remaining third of the galaxies in Virgo Supercluster, including the Milky Way, lie outside the main body of the Supercluster which is the Virgo Strand.

Galaxy distribution

The number density of galaxies in the LS falls off with the square of the distance from its center near the

, suggesting that this cluster is not randomly located. Overall, the vast majority of the luminous galaxies (less than absolute magnitude −13) are concentrated in a small number of

clouds In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles, suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may c ...

(groups of

galaxy cluster A galaxy cluster, or a cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity, with typical masses ranging from 1014 to 1015 solar masses. Clusters consist of galax ...

s). Ninety-eight percent can be found in the following 11 clouds, given in decreasing order of number of luminous galaxies:

Canes Venatici Canes Venatici ( ) is one of the 88 constellations designated by the International Astronomical Union (IAU). It is a small northern constellation that was created by Johannes Hevelius in the 17th century. Its name is Latin for 'hunting dogs', and ...

, 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), and NGC 5643. Of the luminous galaxies located in the disk, one third are in the Virgo Cluster, with the other two thirds located outside of the cluster. 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." A helpful analogy that matches the observed distribution is that of soap bubbles. Flattish clusters and

superclusters A supercluster is a large group of smaller galaxy clusters or galaxy groups; they are among the largest known structures in the universe. The Milky Way is part of the Local Group galaxy group (which contains more than 54 galaxies), which in tu ...

are found at the intersection of bubbles, which are large, roughly spherical (on the order of 20–60 Mpc in diameter) voids in space. Long filamentary structures seem to predominate. An example of this is the

Hydra–Centaurus Supercluster The Hydra–Centaurus Supercluster (SCl 128), or the Hydra and Centaurus Superclusters, was a previously defined supercluster in two parts, which prior to the identification of Laniakea Supercluster in 2014 is the closest neighbour of the former ...

, the nearest supercluster to the Virgo Supercluster, which starts at a distance of roughly 30 Mpc and extends to 60 Mpc.

Cosmology

Large-scale dynamics

Since the late 1980s it has been apparent that not only the

, but all matter out to a distance of at least 50 Mpc is experiencing a bulk flow on the order of 600 km/s in the direction of the Norma Cluster (Abell 3627). 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 toward

Shapley Supercluster The Shapley Supercluster or Shapley Concentration (SCl 124) is the largest concentration of galaxies in our universe that forms a gravitationally interacting unit, thereby pulling itself together instead of expanding with the universe. It appears ...

, with center of Shapley Attractor.

Dark matter

The LS has a total mass ''M'' ≈ 10¹⁵ and a total optical luminosity ''L'' ≈ 3 . This yields a mass-to-light ratio of about 300 times that of the solar ratio (/ = 1), a figure that is consistent with results obtained for other superclusters. By comparison, the mass-to-light ratio for the

is 63.8 assuming a solar absolute magnitude of 4.83, a Milky Way absolute magnitude of −20.9, and a Milky Way mass of . These ratios are one of the main arguments in favor of the presence of large amounts of

dark matter In astronomy, dark matter is an invisible and hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravity, gravitational effects that cannot be explained by general relat ...

in the universe; if dark matter did not exist, much smaller mass-to-light ratios would be expected.

Maps

File:Virgosupercluster atlasoftheuniverse.gif, frame, center, Map of the nearby universe within 100 million light-years from Earth, including a portion of the

Southern Supercluster The Southern Supercluster is a nearby supercluster located around in the constellations of Cetus, Fornax, Eridanus (constellation), Eridanus, Horologium (constellation), Horologium, and Dorado. It was first identified in 1953 by Gérard de Vaucou ...

at the bottom left and the Virgo Supercluster on the right in supergalactic coordinates (click on feature names for more information) circle 473 220 33

circle 339 230 16 Centaurus A/M83 Group circle 349 252 15 M81 group circle 326 264 15 Maffei Group circle 289 292 20 NGC 1023 Group circle 370 236 13 M101 group circle 347 299 20 NGC 2997 Group circle 405 238 20 Canes Venatici I Group circle 426 203 19 NGC 5033 group rect 445 247 508 276 Ursa Major Cluster circle 391 270 18 Leo I Group circle 277 197 25 NGC 6744 Group circle 236 314 22 Dorado Group circle 518 87 40 Virgo III Groups circle 526 225 20 NGC 4697 circle 546 331 34 Leo II Groups circle 165 194 27 NGC 7582 poly 180 356 178 325 252 345 242 378

poly 176 357 239 379 214 413 162 381 Eridanus Cluster rect 295 213 324 239

rect 252 235 304 257 Sculptor Group desc bottom-left File:Nearest Groups of Galaxies atlasoftheuniverse.gif, frame, center, The nearest galaxy groups projected onto the supergalactic plane (click on feature names for more information) circle 333 283 20 NGC 55 rect 399 299 419 325

circle 385 294 14

Large Magellanic Cloud The Large Magellanic Cloud (LMC) is a dwarf galaxy and satellite galaxy of the Milky Way. At a distance of around , the LMC is the second- or third-closest galaxy to the Milky Way, after the Sagittarius Dwarf Spheroidal Galaxy, Sagittarius Dwarf ...

circle 429 267 20 NGC 3109 circle 395 338 16

Messier 31 Messier may refer to: People with the surname *Ashley Messier (born 2002), Canadian ice hockey player *Charles Messier (1730–1817), French astronomer *Doug Messier (born 1936), Canadian ice hockey player and coach *Éric Messier (born 1973), Cana ...

circle 365 335 15 Messier 33 circle 278 311 20 NGC 247 circle 388 119 28 Circinus Galaxy circle 456 124 17 NGC 5128 circle 494 161 20 NGC 5253 poly 475 149 500 133 483 113 463 137 NGC 5102 circle 440 165 28 NGC 5128 Group circle 368 206 27 IC 4662 circle 520 105 20

Messier 83 Messier 83 or M83, also known as the Southern Pinwheel Galaxy and NGC 5236, is a barred spiral galaxy approximately 15 million light-years away in the constellation borders of Hydra (constellation), Hydra and Centaurus. Nicolas-Louis de Lacail ...

rect 699 183 774 265

circle 433 65 22 ESO 274-01 circle 266 177 22 NGC 1313 circle 214 255 20 NGC 625 circle 235 282 16 NGC 7793 rect 435 80 472 107 NGC 4945 circle 184 301 20

NGC 45 NGC 45 is a low surface brightness spiral galaxy in the equatorial constellation of Cetus. It was discovered on 11 November 1835 by the English astronomer John Herschel. The galaxy is located at a distance of 22 million light years and is ...

circle 217 311 17 NGC 253 circle 265 260 22 Sculptor Group rect 368 268 412 284

circle 409 379 25 NGC 1569 circle 296 280 17 NGC 300 circle 424 418 20 IC 342 rect 383 429 415 451 Maffei Group circle 325 442 20 NGC 404 circle 272 508 20 NGC 784 circle 397 510 20 Maffei I rect 353 456 413 478 Maffei II rect 371 526 434 553 Dwingeloo 1 circle 444 481 22 NGC 1560 rect 510 417 537 434

Messier 81 Messier 81 (also known as NGC 3031 or Bode's Galaxy) is a grand design spiral galaxy about 1 E22 m, 12 million light-years away in the constellation Ursa Major. It has a Galaxy#Isophotal diameter, D25 isophotal diameter of . Because of its rela ...

rect 527 433 578 443 IC 2574 rect 500 434 515 450

Messier 82 Messier 82 (also known as NGC 3034, Cigar Galaxy or M82) is a starburst galaxy approximately 12 million light-years away in the constellation Ursa Major. It is the second-largest member of the M81 Group, with the D25 isophotal diameter of . ...

poly 516 434 521 456 554 456 552 447 533 445 523 435 NGC 3077 circle 549 476 18 NGC 2976 circle 604 440 22 NGC 4605 circle 513 479 19 NGC 6503 circle 583 410 13 NGC 5204 circle 559 389 16 NGC 3738 circle 512 401 14 NGC 4236 rect 452 442 485 461 NGC 2366 rect 451 420 484 440

NGC 2403 NGC 2403 (also known as Caldwell 7) is an intermediate spiral galaxy in the constellation Camelopardalis. It is an outlying member of the M81 Group, and is approximately 8 million light-years distant. It bears a similarity to Messier 33, M33, con ...

rect 485 433 502 465 NGC 4305 circle 659 382 20 NGC 5023 rect 634 344 658 364 Messier 94 circle 618 355 15 NGC 4244 circle 594 337 13 NGC 4214 circle 577 361 19 NGC 4449 circle 615 319 17 NGC 4395 rect 591 280 640 304 Canes I Group poly 528 393 542 392 558 411 525 414 M81 Group desc bottom-left

Diagrams

References

External links

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). {{Portal bar, Stars, Astronomy, Science Galaxy superclusters Laniakea Supercluster