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Galaxy groups

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Local group

 Updated June 01, 2013

The Milky Way and the Big Nebula of Andromeda have satellite galaxies. These two huge spirals belong to an even bigger grouping of 20 galaxies among which M31, M33, Maffei I and Maffei II, the Big and the Small Cloud of Magellan, conscript Groups it local. All these galaxies move around a common center situated between our Galaxy and the Nebula of Andromeda. All the observers know the biggest and the most brilliant of all: M31, in the constellation of Andromeda. The most known heap of galaxies are Virgo, Pegasus I, Pisces, Cancer, Perseus, Coma, Ursa Major III, Hercules, Pegasus, Heap A, Centaurus, Ursa Major I, Leo, Gemini, Corona Borealis, Heap B, Bootes, Ursa Major II, Hydra II Distant from 2,5 million light years, it is the closest galaxy but especially it is the only one who is visible in the bare eye, on dark night. We can consider the Local Group, or the other groups looking like it as heap containing a number relatively restricted by objects. Galaxy groups can be more important. If we come down until the magnitude 21, there would so be 75 million galaxies among which our.


The local group is a part of an enormous complex of 10000 galaxies assembled in heap extending over some 200 million years lights, conscript local super clusters or super clusters of the Virgo. The super clusters of the Virgo and super clusters of the Hydra and the centaur fall themselves towards another big conglomeration of galaxy groups which we call the Big Attractor. Galaxy comes from Greek " galactos " which wants to say milk. Of our ground base, we participate in a fantastic cosmic ballet: the Earth propels us in 30 km/s around the Sun which splits the space in 230 km/s around the Milky Way.
This one falls in his turn towards the galaxy of Andromeda in km/s 90, each of its galaxies rush in 45 km/s towards the center of the local Group, our galaxies group. The local Group moves in 600 km/s attracted by the galaxies group of the Virgo and the super clusters of the Hydra and the Centaur, who falls in his turn towards the big Attractor.

 Local Group of galaxies, Milky Way, Andromède and Triangulum

Image: few galaxies in our Local Group of galaxies. Author Richard Powell.

Galaxies group Virgo


The heap of the Virgo (Virgo) is a massive group of galaxies which dominates the super clusters of the Virgo. It is the closest heap of galaxies of our Galaxy, the Milky Way. There are approximately 2000 galaxies in this heap (but 90 % of them are dwarfish galaxies).
This heap is one diameter of about 15 million years light, hardly more than our Local Group, but it contains fifty times more galaxies.


Image: The group of galaxies Virgo, dominated by M86 (at the top), M84 (to the right), NGC 4388 below and NGC 4387 in the middle.
source: Hawaiian Starlight, CFHT

 group of galaxies Virgo

Galaxies group Coma


The heap of Coma is a galaxies group, spherical, very dense in its center.
It contains more than thousand galaxies and is situated, in 300 million light years with the heap Virgo in the constellation of the Virgo.


Image: Galaxies group Coma

The super clusters of Coma (Bernice's Hair) is one of galaxies group the most known.

 super clusters of Coma

Galaxies group Fornax


The group of galaxies Fornax is in about 65 million light years of the Earth. The galaxies of the heart of the heap Fornax seem to move in the direction of a common point, attracted by the dominant gravity of invisible structures of dark matter of this region.
There is in the direction where is situated the System of the Furnace a dwarfish galaxy, distant from 600  000 light years.
It belongs to the Local Group, that is to the small heap of galaxies in which is also the Milky Way, our galaxy.


Image: The group of galaxies Fornax of the look-out observatory Chandra reveals emissions with high energy of several huge galaxies close to the center of the heap Fornax and an immense diffuse cloud of warm gas emitting X-rays.

 galaxies Fornax

Galaxies group Shapley


On the photo above, the blue objects are galaxies and the yellow objects are stars in the foreground.
In the center of the group, we find a gigantic elliptic galaxy (ESO444-46) of a diameter of more than 340 000 light years.


Image: clusters Shapley A3558

 clusters Shapley A3558

Cluster of galaxies Abell 2744


The Hubble Space Telescope still amazes us with this cluster of galaxies Abell 2744 is the most massive and deepest ever photographed all clusters of galaxies. This photograph shows some of the youngest galaxies ever detected in the deep cosmos. The immense gravity of the cluster Abell 2744 distorts space so that the image we see is distorted by the curvature, as through a lens we see the magnified galaxies that are much farther behind Abell 2744.
The most distant galaxies are about 12 billion years, they were born shortly after the Big Bang. In this exhibition Hubble reveals nearly 3000 background galaxies interspersed with images of hundreds of galaxies leading belonging to the cluster. Far Away Galaxies appear not only brilliant, but also stained, stretched and duplicated through the gravitational field of Abell 2744. The gravitational lensing amplifies the background galaxies, as much as 10 to 20 times they are brighter and larger than they really are. Moreover most of these galaxies would be invisible without the gravitational lensing.


Long exposure Hubble images will be combined with Spitzer and Chandra X-ray Observatory NASA to provide new insights into the origin and evolution of galaxies and their black holes companions.

Image: This long exposure of the galaxy cluster Abell 2744 is performed by the Hubble Space Telescope. The image of the cluster massive galaxies (foreground) is the deepest ever made. The farthest galaxies around 12 billion years, they were born shortly after the Big Bang.

 Cluster of galaxies Abell 2744

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