Abell Galaxy Clusters and Nearby Superclusters
Abell Galaxy Clusters and Nearby Superclusters
| Group Name | Abell |
| Reference | A Catalog of Rich Clusters of Galaxies (Abell+ 1958, 1989) With alterations by R. Brent Tully (U Hawaii) |
| Prepared by | R. Brent Tully (U Hawaii)
Stuart Levy (NCSA/U Illinois) |
| Labels | Yes |
| Files | abell.speck, abell.label |
| Dependencies | abell.cmap |
| Census | 2,246 galaxy clusters |
The Abell group is composed of all the nearby galaxy clusters. The northern hemisphere survey, published in 1958, was compiled by George Abell (1927-1983) from the Palomar Sky Survey plates. A subsequent southern hemisphere catalog was published posthumously in 1989. Further data analysis was conducted by R. Brent Tully of the University of Hawaii to determine the distance and three-dimensional distribution of these galaxy clusters.
Each point in this data set represents a cluster of tens to hundreds (possibly even thousands) of galaxies. You will notice some points are assigned colors while most are gray. The data set also has an arbitrary cut-off, resulting in the rectangular shape of the data set.
Clusters of Clusters
Galaxies group together to form the large-scale structure of the Universe. Dense clusters of galaxies are connected by filaments, or strands, of galaxies. Between, vast voids resemble the inside of a bubble and are occupied by less dense material. Beyond these structures, astronomers have found larger-scale constructs called “superclusters.”
Larger than a cluster of galaxies, superclusters are made from many galaxy clusters. In the Abell data, the non-gray colors represent these superclusters. These mammoth objects are on the order of 300 million light-years in diameter. Compare that to the size of one cluster, Virgo, which is only 15 million light-years across, or our Galaxy, which is a scant 100,000 light-years across.
The Shapley concentration (named after the American astronomer Harlow Shapley (1885-1972) is one of the closest rich superclusters to us. Six hundred million light-years distant, the supercluster is composed of about 25 rich galaxy clusters, amounting to 10,000 Milky Ways.
Notable Clusters
One way to see the superclusters is to filter Abell by the notable index. Each Abell cluster has a notable index that is either 1, meaning the cluster is attached to a large supercluster, or zero, meaning it is relatively isolated. Type see supercl, and 313 galaxy clusters in about two dozen superclusters will remain. Type see all to return all the galaxy clusters to view.
Labels
Two sets of labels describe the Abell data group, the supercluster labels and the individual cluster labels. The handful of large, white labels describe supercluster positions. Approach a particular Abell cluster and you will see a blue-green label pop on, revealing its Abell catalog number. Of course, you can adjust the appearance and visibility of these labels using the labelsize and labelminpixels commands.
© 2002-2005 American Museum of Natural History
Last Modified: 2007-12-19 by Brian Abbott