The Vela Supercluster (Vela SCl, VSCL) is a massive galactic

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 turn ...

about 265.5

megaparsec The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, and ...

s (870 million

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s) away within the vicinity of the

Zone of Avoidance The Zone of Avoidance (ZOA, ZoA), or Zone of Galactic Obscuration (ZGO), is the area of the sky that is obscured by the Milky Way. The Zone of Avoidance was originally called the Zone of Few Nebulae in an 1878 paper by English astronomer Richard ...

, centered on the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Vela. It is one of the largest structures found in the universe, covering about 25 × 20 degrees of the sky. It consists of two

walls Walls may refer to: *The plural of wall, a structure * Walls (surname), a list of notable people with the surname Places * Walls, Louisiana, United States *Walls, Mississippi, United States * Walls, Ontario, neighborhood in Perry, Ontario, C ...

: a broad main wall and a secondary merging wall. The combined dimensions of the walls are 115 km/s Mpc on the major dimensions and 90 km/s Mpc on the minor ones, which corresponds to about 385 million and 300 million light years, respectively. It is about 1,000 times the mass of the Milky Way galaxy, which corresponds to a mass of . About 20 initial

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. They are the second-l ...

s have been identified spectroscopically.

Supercluster

The supercluster's discovery was reported in December 2016 by Kraan-Korteweg ''et al.'' through an analysis of the redshifts of 4500 galaxies from the combined data of the

2dF Galaxy Redshift Survey In astronomy, the 2dF Galaxy Redshift Survey (Two-degree-Field Galaxy Redshift Survey), 2dF or 2dFGRS is a redshift survey conducted by the Australian Astronomical Observatory (AAO) with the 3.9m Anglo-Australian Telescope between 1997 and 11 A ...

which uses the AAOmega fiber optics from the

Anglo-Australian Observatory The Australian Astronomical Observatory (AAO), formerly the Anglo-Australian Observatory, was an optical and near-infrared astronomy observatory with its headquarters in North Ryde in suburban Sydney, Australia. Originally funded jointly by the U ...

(AAO), and the South African Large Telescope (SALT). The supercluster is located in a region obstructed by the view of the Milky Way's disc due to our position inside the disc. This region is known colloquially as the

. Hence, the supercluster can only be studied at longer wavelengths (

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

microwave Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ran ...

radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmit ...

) which can pass through the gases and dust of the Milky Way disc. The supercluster is close to the location where the Milky Way, and hence the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...

, is currently moving toward with respect to the

cosmic microwave background In Big Bang cosmology the cosmic microwave background (CMB, CMBR) is electromagnetic radiation that is a remnant from an early stage of the universe, also known as "relic radiation". The CMB is faint cosmic background radiation filling all spac ...

, a phenomenon known as the

dark flow In astrophysics, dark flow is a theoretical non-random component of the peculiar velocity of galaxy clusters. The actual measured velocity is the sum of the velocity predicted by Hubble's Law plus a possible small and unexplained (or ''dark'') v ...

. This movement was found to be significant relative to the normal

Hubble flow Hubble's law, also known as the Hubble–Lemaître law, is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In other words, the farther they are, the faster they are moving a ...

of the galaxies caused by the

metric expansion of space The expansion of the universe is the increase in distance between any two given gravitationally unbound parts of the observable universe with time. It is an intrinsic expansion whereby the scale of space itself changes. The universe does not exp ...

. Although the

Planck spacecraft ''Planck'' was a space observatory operated by the European Space Agency (ESA) from 2009 to 2013, which mapped the anisotropies of the cosmic microwave background (CMB) at microwave and infrared frequencies, with high sensitivity and small angu ...

showed no evidence for this flow, propositions to explain this bulk movement includes the influence of the nearby

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

and the

Great Attractor The Great Attractor is a gravitational anomaly in intergalactic space and the apparent central gravitational point of the Laniakea Supercluster. The observed anomalies suggest a localized concentration of mass millions of times more massive than ...

at the center of the

Laniakea Supercluster The Laniakea Supercluster (; Hawaiian for "open skies" or "immense heaven") is the galaxy supercluster that is home to the Milky Way and approximately 100,000 other nearby galaxies. It was defined in September 2014, when a group of astronom ...

. The Vela Supercluster is estimated to contribute at least of this bulk movement. The paper reporting the discovery describes the supercluster as ''

Terra incognita ''Terra incognita'' or ''terra ignota'' (Latin "unknown land"; ''incognita'' is stressed on its second syllable in Latin, but with variation in pronunciation in English) is a term used in cartography for regions that have not been mapped or do ...

'' (Latin for "unknown land"), an unknown great continent in the nearby Universe whose outline we are only beginning to discern." More comprehensive surveys in the future, such as the Taipan Galaxy Surveys, are expected to provide additional data about the supercluster.

References

External links

* * {{DEFAULTSORT:Vela Supercluster Vela (constellation) Galaxy superclusters Astronomical objects discovered in 2016

Supercluster

See also

Further reading

References

External links