The Corona Borealis Supercluster

Although it is one billion light years from us, the Corona Borealis supercluster is famous because it is a fairly obvious concentration of clusters of galaxies. This map shows every galaxy brighter than magnitude 17 (from the HyperLeda database) in this area of the sky. The locations of the major clusters of galaxies in the Corona Borealis supercluster are marked in the centre. On the left side of the map lies part of the Hercules supercluster at about half the distance.

The Corona Borealis Supercluster

Below is a list of the Corona Borealis Supercluster clusters. A2065 is the most famous of these clusters although a lot of the other clusters here are also quite rich. Two of these clusters, A2122 and A2124, are actually the same cluster. A2124 is the center of the cluster and A2122 is an extension of it.

   1           2       3        4         5       6      7                    
 Abell         Equatorial    Redshift  Distance  Rich  Notes                  
 Number       Coordinates       z        Mly                                  
              RA       Dec                                                    
 A2005      14 58.7  +27 49   .0762     1025      2                           
 A2019      15 03.0  +27 11   .0795     1065      0                           
 A2022      15 04.3  +28 25   .0566      770      1    foreground cluster     
 A2056      15 19.2  +28 16   .0834     1115      1                           
 A2061      15 21.3  +30 39   .0772     1035      1                           
 A2065      15 22.7  +27 43   .0714      960      2    Corona Borealis cluster
 A2067      15 23.2  +30 54   .0736      990      1                           
 A2079      15 28.1  +28 53   .0649      875      1                           
 A2089      15 32.7  +28 01   .0720      970      1                           
 A2092      15 33.3  +31 09   .0657      890      1                           
 A2122      15 44.5  +36 08   .0649      875      1                           
 A2124      15 45.0  +36 04   .0649      875      1                           
Column 1: The name/number of the cluster.
Column 2: The Right Ascension for epoch 2000.
Column 3: The Declination for epoch 2000.
Column 4: The redshift of the cluster.
Column 5: The distance in millions of light years assuming H=70km/s/Mpc.
Column 6: The 'richness' class of the cluster.
Column 7: Additional names and notes.

Abell G, Corwin H, Olowin R, (1989), A catalogue of Rich Clusters of Galaxies, 
          Astrophys J Supp, 70, 1.
Struble M, Rood H, (1999), A compilation of redshifts and velocity dispersions for 
          ACO clusters, Astrophys J, 125, 35.

A2065 - The Corona Borealis Cluster

Below is a picture of the centre of the A2065 cluster. This cluster is often called the Corona Borealis cluster. It is the richest cluster of galaxies in the Corona Borealis supercluster. This cluster is famous mainly because it was one of several clusters used by Milton Humason and Edwin Hubble in the 1930's to demonstrate that the universe is expanding.

A2065 - from the Digitized Sky Survey
A map of the A2065 cluster

This is a map of the A2065 cluster. This map shows 119 of the brightest galaxies in this cluster. A lot of the galaxies in this cluster have not been accurately classified, so some of the classifications used in this map are probably wrong, although it is clearly a cluster which contains a wide variety of different galaxy types.

The Scientific Study of the Corona Borealis Supercluster

The possibility that there might be a supercluster in Corona Borealis was first suggested in the 1950's. George Abell examined his own catalogue of Rich Clusters of Galaxies (published in 1958) and in a paper published in 1961, he included the Corona Borealis supercluster as supercluster number 13 in a list of 17 possible superclusters.

The first proper study of the Corona Borealis supercluster was published by M Postman, M Geller and J Huchra in 1988. They studied the motion of seven of the clusters in the supercluster, and they estimated the mass of the supercluster.

More recently, in 1997 and 1998, T Small, C Ma, W Sargent and D Hamilton, published three papers about this supercluster (1, 2, 3). They noticed the presence of another supercluster behind the Corona Borealis supercluster (associated with A2034, A2049, A2062, A2069 and A2083) at a distance of 1.5 billion light years (redshift 0.113). They also believe that the clusters at the centre of the Corona Borealis supercluster are collapsing together and will eventually form one big cluster.

F Kopylova and A Kopylov agree with them. They published evidence in 1998 that the core of the supercluster (consisting of A2061, A2065, A2067, A2089 and A2092) is "in a stage of rapid gravitational collapse," (on a timescale of billions of years).

The Corona Borealis cluster (A2065) was discovered by Edwin Hubble in the 1930's. In 1936, Milton Humason measured the redshift of one of the galaxies (PGC 54876) in the cluster as part of a project to demonstrate that velocity is proportional to distance for a large number of distant clusters. This was powerful evidence that the universe is expanding.

Below - a picture of the A2061 cluster. This is another of the rich clusters of galaxies in the Corona Borealis supercluster. The large elliptical galaxy near the centre is PGC 54787.

A2061 - from the Digitized Sky Survey
The nearest superclusters Back to the Neighbouring Superclusters page