Galaxy clusters are the largest gravitationally bound structures in the universe. They gather in superclusters, and our own galaxy, the Milky Way, is part of the Local Group, which contains about 40 galaxies. In addition, the Milky Way belongs to an even larger supercluster of galaxies: the Laniakea Supercluster. The latter extends over nearly 500 million light-years and contains more than 100,000 galaxies1.
The Virgo Cluster is a large cluster of galaxies located at a distance of 15 to 22 Mpc (∼48.9 to 71.8 million light-years). It was discovered by Charles Messier in 1781, who mapped many of its most important galaxies, including the giant galaxy M87. This cluster is at the center of the Virgo Supercluster, which includes the Local Group and a fortiori the Milky Way. It is located in the constellation Virgo and has an angular diameter of about 8 degrees. It contains approximately 1,300 to 2,000 galaxies, many of which are visible with a small telescope. The precise distance to the cluster is poorly known; current best estimates, based on Cepheids using the Hubble Space Telescope, give an average distance of about 20 megaparsecs (65 million light-years). The cluster is an irregular cluster of at least three subclusters centered on the galaxies M87, M86, and M49. The largest is the one centered on M87, with a mass of approximately 10^14 solar masses, which is about an order of magnitude larger than the other two.
The Coma Cluster, also known as the Coma Cluster (Abell 1656), is a large galaxy cluster that contains over 1000 identified galaxies. Located about 99 million light-years from Earth, it is part of the Coma Berenices Supercluster. The ten brightest spiral galaxies in this cluster have an apparent magnitude between 12 and 14 and can be observed with an amateur telescope with a diameter greater than 200 mm. The central region of the cluster is dominated by two giant elliptical galaxies: NGC 4874 and NGC 4889.
The Fornax Cluster is a relatively nearby group of galaxies, located about 65 million light-years from Earth. It is mainly located in the constellation Fornax (the Furnace). With over 600 member galaxies, the Fornax cluster is the second “richest” (most populated) galaxy cluster within 100 million light-years of our galaxy (after the much larger Virgo cluster). Two elliptical galaxies dominate the center of this cluster: NGC 1399 and NGC 1404. These galaxies contain much older stars than the picturesque spiral galaxies and are held together by the force of gravity. Another galaxy, NGC 1427A, is in the lower left corner of the image. This irregular galaxy is moving toward the heart of the cluster at high speed and will eventually undergo gravitational interactions with other galaxies, causing it to disintegrate. The Fornax Cluster is a fascinating object for the study of galactic dynamics and dark matter.
The Shapley Supercluster, also called the Shapley Concentration (SCl 124), is a supercluster of galaxies located in the constellation Centaurus. It lies at a distance of about 650 million light-years (redshift, z = 0.046). Discovered by Harlow Shapley in 1936, it consists of about 76,000 galaxies, with a luminosity exceeding 18th apparent magnitude. This supercluster is notable for its large linear dimension, large population, and distinctive elongated shape. Today, it is considered the core or nucleus of the Shapley Supercluster. In 1989, Somak Raychaudhury of the University of Cambridge rediscovered this supercluster as a whole using the plates of the UK Schmidt Telescope and the Automated Plate Measurement (APM) system. The Shapley supercluster is also linked to the Great Attractor, a concentration of mass located in the same direction as the supercluster, towards Centaurus.
The Hydra Cluster (Abell 1060) is a cluster of galaxies located in the constellation Hydra. It contains 157 bright galaxies.1 The cluster is 10 million light-years across and contains a large portion of dark matter. Among its members, NGC 3311 is the brightest galaxy, with a magnitude around 12. NGC 3309 and NGC 3311 are elliptical galaxies, while NGC 3312 is a spiral galaxy with a diameter of 150,000 light-years.
Le Quintette de Stephan est un regroupement visuel de galaxies situé dans la constellation de Pégase. Il fut découvert par l’astronome français Édouard Stephan en 1877. Plusieurs galaxies de ce groupe montrent des signes de violentes interactions gravitationnelles avec des formes distordues et de longs filaments d’étoiles et de gaz s’étendant très loin du corps des galaxies. Le Quintette est un prototype d’une classe d’objets connus sous le nom de groupes compacts de galaxies et a été étudié de manière intensive pendant des décennies1.
The Perseus Cluster (or Abell 426) is a galaxy cluster located in the constellation Perseus. Its velocity relative to the cosmic microwave background is 4,995 ± 60 km/s, which corresponds to a Hubble distance of 73.7 ± 5.3 Mpc (∼240 million light-years)1. It is part of the Perseus-Pisces Supercluster. The cluster contains about 190 galaxies, among the approximately 1,000 galaxies in the Perseus-Pisces Supercluster. It is the brightest galaxy cluster in the X-ray domain2. The X-ray radiation comes from the thermal emission of the gas (plasma) of the cluster, which is concentrated in its center. The radio galaxy NGC 1275 (Perseus A, also known as 3C84) is the brightest in the cluster. It is a cD galaxy and is among the most massive galaxies in the universe. NGC 1265 (3C 83.1B) is another interesting radio galaxy in the cluster, with relativistic jets of radio emission curving over hundreds of kiloparsecs. The Perseus cluster is relatively close, allowing detailed observations of its X-ray emission using the Chandra Space Telescope.
The Seyfert Sextet is a group of galaxies located in the constellation Serpens, about 200 million light-years (60 Mpc) from the Milky Way. Although it appears to be made up of six galaxies, it actually contains only five that are interacting:
NGC 6027: the brightest of the group, a lenticular galaxy in the middle of the group.
NGC 6027a: a spiral galaxy with a diffuse halo recognizable by its dust belt.
NGC 6027b: almost in contact with the two previous ones.
NGC 6027c: a well-defined barred spiral galaxy seen almost edge-on.
NGC 6027d: a spiral galaxy seen from above, further away than the four previous ones and which therefore does not interact with the other members of the group.
The Seyfert Sextet is one of the most compact groups of galaxies known, covering less than 100,000 light-years (30 kpc), the width of the Milky Way. Each of the interacting galaxies has a width that does not exceed 35,000 light-years (10.75 kpc).
Why are Galaxies, Unlike Stars, So Close to Each Other? 
The hidden galaxy, one of Euclid's first images 
The Virgo Cluster spans approximately three Full Moons 
Where did the dark matter in our Galaxy go? 
Merging galaxies and black holes 
Mirages created by gravitational lenses 
Mystery of the Big Bang, the problem of the horizon 
Cartwheel Galaxy Cosmic Event 
The first second of our history 
A small galaxy tears apart the large NGC 6745 
The mystery of gamma bursts 
The Cigar Explosion 
Shockwaves
Gould's belt, a stellar fireworks display 
Recombination
in cosmology 
Journey to the center of our galaxy 
Lyman-alpha
bubbles 
Andromeda in the ultraviolet 
The most beautiful galaxy clusters 
Tinkerbell merger of three galaxies 
A gigantic black hole 
Enigma
of coplanar galaxies 
The cluster of galaxies Coma in its soup 
The cannonball, proof of dark matter 
El Gordo galaxy cluster 
Einstein
ring and cross 
How to measure distances in the Universe? 
The Hubble sequence and types of galaxies 
The spiral shape of the galactic arms 
Even more stars, the Cigar galaxy 
The
Universe of X-rays 
The most beautiful galaxies 
The oldest galaxies in the universe 
Quasars
the nuclei of galaxies 
Sagittarius A black hole at the center of our Galaxy 
The MOND theory and its contradiction 
The first image of a black hole 
Central
area of the Milky Way 
Laniakea, our supercluster of galaxies