Bautz–Morgan classification explained

The Bautz–Morgan classification was developed in 1970 by Laura P. Bautz and William Wilson Morgan to categorize galaxy clusters based on their morphology.^[1] It defines three main types: I, II, and III. Intermediate types (I-II, II-III) are also allowed. A type IV was initially proposed, but later redacted before the final paper was published.^[2]

Classification

• A type I cluster is dominated by a bright, large, supermassive cD galaxy; for example Abell 2029 and Abell 2199.
• A type II cluster contains elliptical galaxies whose brightness relative to the cluster is intermediate to that of type I and type III. The Coma Cluster is an example of a type II.
• A type III cluster has no remarkable members, such as the Virgo Cluster. Type III has two subdivisions, type IIIE and type IIIS
  • Type IIIE clusters do not contain many giant spirals
  • Type IIIS clusters contain many giant spirals
• The deprecated type IV was for clusters whose brightest members were predominantly spirals.^[2]

Examples

	Example	Type	width=100%	Notes
	Abell 2199
	Abell S740
	Coma Cluster
	Abell 1689
	Virgo Cluster

See also

• Active galactic nucleus
• Galaxy morphological classification
• List of Abell clusters
• Planet
• Stellar classification

Notes and References

1. Bautz . L. P. . Laura P. Bautz . Morgan . W. W. . William Wilson Morgan . December 1970 . On the Classification of the Forms of Clusters of Galaxies . Astrophysical Journal . 162 . L149 . A&AA ID. AAA004.160.015 . 1970ApJ...162L.149B . 10.1086/180643 . March 10, 2012 .
2. Bautz . Laura P. . Laura P. Bautz . Morgan . W. W. . William Wilson Morgan . September 1970 . Preliminary Classification of Clusters of Galaxies . Bulletin of the American Astronomical Society . 2 . 294 . A&AA ID. AAA004.160.006 . 1970BAAS....2R.294B . March 10, 2012 .