““the great the great attractor”attractor”

mia kumagaimia kumagai

astr007.301astr007.301

4.21.064.21.06

what what isis the great the great attractor?attractor?

a gravitational anomaly in a gravitational anomaly in intergalactic space at the center intergalactic space at the center of the local supercluster which of the local supercluster which reveals the existence of a reveals the existence of a localized concentration of mass localized concentration of mass equivalent to tens of thousands of equivalent to tens of thousands of galaxiesgalaxies

observable by its effect on the observable by its effect on the motion of galaxies over a region motion of galaxies over a region hundreds of millions of lightyears hundreds of millions of lightyears acrossacross

these galaxies are all redshifted, these galaxies are all redshifted, in accordance with the Hubble in accordance with the Hubble Flow, indicating that they are Flow, indicating that they are receding relative to us and to each receding relative to us and to each other, but the variations in their other, but the variations in their redshift are sufficient to reveal redshift are sufficient to reveal the existence of the anomalythe existence of the anomaly

where where isis the Great the Great Attractor?Attractor?

discovered in 1986, it is located discovered in 1986, it is located in the direction of the Hydra in the direction of the Hydra and Centaurus constellationsand Centaurus constellations

a group of astronomers known a group of astronomers known as the "Seven Samurai" (David as the "Seven Samurai" (David Burstein, Roger Davies, Alan Burstein, Roger Davies, Alan Dressler, Sandra Faber, Dressler, Sandra Faber, Donald Lynden-Bell, Roberto J. Donald Lynden-Bell, Roberto J. Terlevich, and Gary Wegner) Terlevich, and Gary Wegner) found that galaxies are very found that galaxies are very unevenly distributed in space, unevenly distributed in space, with galactic superclusters with galactic superclusters separated by incredibly huge separated by incredibly huge voids of visible ordinary mattervoids of visible ordinary matter

what what isis the Great the Great Attractor?Attractor?

the Great Attractor is one such the Great Attractor is one such structure, a diffuse structure, a diffuse concentration of matter some concentration of matter some 400 million light-years in size 400 million light-years in size located around 250 million located around 250 million light-years away in the light-years away in the direction of the southern direction of the southern Constellation Centaurus, about Constellation Centaurus, about seven degrees off the plane of seven degrees off the plane of the Milky Way -- at a redshift-the Milky Way -- at a redshift-distance of 4,350 kilometers (or distance of 4,350 kilometers (or around 2,700 miles) per secondaround 2,700 miles) per second

a diffuse mass concentration a diffuse mass concentration 250 million light-years away 250 million light-years away but so large it pulls our own but so large it pulls our own Milky Way Galaxy along with Milky Way Galaxy along with millions of others towards itmillions of others towards it

observing the Great observing the Great AttractorAttractor

calculations indicate that ~10calculations indicate that ~101616 solar solar masses concentrated 65 Mpc away masses concentrated 65 Mpc away in the direction of Centaurus would in the direction of Centaurus would account for thisaccount for this

detailed investigation of that region detailed investigation of that region of the sky 10 times too little visible of the sky 10 times too little visible matter to account for this flow, again matter to account for this flow, again implying a dominant gravitational implying a dominant gravitational role for unseen or dark matter role for unseen or dark matter

thus the Great Attractor is certainly thus the Great Attractor is certainly there (because we see its there (because we see its gravitational influence), but the gravitational influence), but the major portion of the mass that must major portion of the mass that must be there cannot be seen in our be there cannot be seen in our telescopestelescopes

attempts to further study the Great attempts to further study the Great Attractor and other phenomena are Attractor and other phenomena are hampered due to the line of sight hampered due to the line of sight obstruction by its location in the obstruction by its location in the zone of avoidance (the part of the zone of avoidance (the part of the night sky obscured by the Milky Way night sky obscured by the Milky Way galaxy)galaxy)

the Great Attractor in the Great Attractor in fictionfiction

tthe Great Attractor is an he Great Attractor is an element of Stephen Baxter's element of Stephen Baxter's Xeelee Sequence of novelsXeelee Sequence of novels

In the motion picture In the motion picture Men In Men In BlackBlack, J (Will Smith) , J (Will Smith) accidentally sends a small, accidentally sends a small, shiny object flying and shiny object flying and bouncing around MIB bouncing around MIB headquarters, causing a headquarters, causing a commotion. K (Tommy Lee commotion. K (Tommy Lee Jones) explains to him that it Jones) explains to him that it was a gift from the Great was a gift from the Great Attractor, who thought it was Attractor, who thought it was "funny as hell.”"funny as hell.”

In Terry Pratchett’s In Terry Pratchett’s Discworld Discworld series, Azrael, the cosmic series, Azrael, the cosmic representation of the Death of representation of the Death of Universes, is known as the Universes, is known as the Great Attractor.Great Attractor.

summary:summary: the Great Attractor is far bigger than a galaxythe Great Attractor is far bigger than a galaxy the Great Attractor is a supercluster, or something even bigger the Great Attractor is a supercluster, or something even bigger the gravity of the Great Attractor has been pulling the Milky Way in the gravity of the Great Attractor has been pulling the Milky Way in

its direction - the motion of local galaxies indicated there was its direction - the motion of local galaxies indicated there was something massive out there that are pulling the Milky Way, the something massive out there that are pulling the Milky Way, the Andromeda Galaxy, and other nearby galaxies towards itAndromeda Galaxy, and other nearby galaxies towards it

for a while, nobody could see what it was, because it lies behind the for a while, nobody could see what it was, because it lies behind the plane of our galaxy, meaning the gas and dust in our Galaxy plane of our galaxy, meaning the gas and dust in our Galaxy obscures the light from the Great Attractor, and it is outshone by obscures the light from the Great Attractor, and it is outshone by the stars and other objects in our Galaxythe stars and other objects in our Galaxy

x-ray observations with the ROSAT satellite then revealed that Abell x-ray observations with the ROSAT satellite then revealed that Abell 3627, a previously known cluster of galaxies, was much more 3627, a previously known cluster of galaxies, was much more massive than originally suspected, containing many more galaxiesmassive than originally suspected, containing many more galaxies

optical astronomers had missed a great number of galaxies, because optical astronomers had missed a great number of galaxies, because of the obscuration, but with hindsight (and with better of the obscuration, but with hindsight (and with better observations), could spot many more galaxies. It is now thought that observations), could spot many more galaxies. It is now thought that the Great Attractor is probably a supercluster, with Abell 3627 near the Great Attractor is probably a supercluster, with Abell 3627 near its centerits center

sites referenced:sites referenced:

••http://archive.ncsa.uiuc.edu/Cyberia/Cosmos/http://archive.ncsa.uiuc.edu/Cyberia/Cosmos/GtAttractor.htmlGtAttractor.html

••http://csep10.phys.utk.edu/astr162/lect/http://csep10.phys.utk.edu/astr162/lect/gclusters/attractor.htmlgclusters/attractor.html

••http://en.wikipedia.org/wiki/Great_Attractorhttp://en.wikipedia.org/wiki/Great_Attractor

• • http://www.solstation.com/x-objects/greatatt.htmhttp://www.solstation.com/x-objects/greatatt.htm

••http://cow.physics.wisc.edu/~ogelman/guide/gr8a/http://cow.physics.wisc.edu/~ogelman/guide/gr8a/