Astronomy Answers: Universe Family Tree: Galaxy Cluster Cloud

# Astronomy AnswersUniverse Family Tree: Galaxy Cluster Cloud

1. References

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 Type :  Supercluster ───  Galaxy Cluster Cloud ───  Galaxy Cluster Size :  77 Mpc ───  23 Mpc ───  8 Mpc Earth :  Local Supercluster ───  Canes Venatici Cloud ───  Local Group

Sometimes it is convenient to divide a supercluster into several groups of galaxy clusters, especially if the supercluster is a poor (irregular) one. Such groups are bigger than a galaxy cluster but smaller than a supercluster. We'll call them galaxy cluster clouds. It is not clear to me if there is a (different) standard name for them.

For example, the Local Supercluster has been divided into several clouds of galaxies (see the first table on the page about superclusters) [1], of which the Canes Venatici cloud harbors our own Galaxy. This cloud has the shape of a flat disk, 0.3 Mpc thick and with a radius of about 19 Mpc. This cloud of galaxies contains the Local Group and several galaxy clusters defined by [2], as listed in the following table. "G" stands for the de Vaucouleurs number of the group, "Name" is the proper name used by de Vaucouleurs, "Dist" is the revised distance from [2] (1973) in Mpc, "Brightest" lists the identification of the brightest member galaxy of the group, "B(0)" is the standard face-on B magnitude of that brightest member.

Table 1: Nearby Galaxy Clusters

G Name Dist Brightest B(0)
1 Sculptor 2.5 NGC 253 8.1
2 M 81 group 3.0 M 81 7.9
3 CVn I 4.5 NGC 4736 8.9
4 NGC 5128 group 4.0 NGC 5236 8.2
5 M 101 group 5.5 M 101 8.6
10 CVn II 7.3 NGC 4631 10.0
13 Coma I 8.1 NGC 4725 10.2
17 UMa I (Z) 11.8 NGC 4151 11.5
24 UMa I (Y) 14.7 NGC 3776 11.1
28 UMa I (X) 10.7 NGC 3310 11.2
32 UMa I (S) 15.2 NGC 3938 11.0
34 UMa I (N) 12.8 NGC 3992 10.8
41 NGC 2768 group 13.7 NGC 2768 11.5

## 1. References

1. "The Local Supercluster", R. Brent Tully, Astrophys. J., vol. 257, pp. 389-422 (1982) [ADS 1982ApJ...257..389T]
2. "Nearby Groups of Galaxies", G. de Vaucouleurs, Chapter 14 in "Galaxies and the Universe", Editors: Allan Sandage, Mary Sandage, and Jerome Kristian, Volume 9 of "Stars and Stellar Systems", General Editor: Gerard P. Kuiper; University of Chicago Press (Midway Reprint), ISBN 0-226-45970-5 (1975).

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Last updated: 2021-07-19