Published in Astrophysical Journal, vol. 162, p.L149, 1970

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ON THE CLASSIFICATION OF THE FORMS OF CLUSTERS OF GALAXIES

L. P. Bautz

Dearborn Observatory, Northwestern University

AND

W. W. Morgan

Yerkes Observatory, University of Chicago


Abstract. A classification of clusters of galaxies based on the relative contrast of the brightest member galaxy is described. Clusters containing a supergiant D galaxy define Type I; at the other extreme (Type III) are clusters which contain no members significantly brighter than the general bright population. A list of seventy-six clusters classified according to the present system is included.


Terminology. Compact cluster; medium compact cluster; open cluster. - The galaxy-cluster classification of Zwicky, Herzog, and Wild (1961).

Regular cluster, Irregular cluster. - The two-part classification of Abell (1965; 1970).

Com; Vir; UMa. - Standard clusters of galaxies in the classification of Morgan (1962).

D galaxy. - A galaxy which has, on ordinary photographs, an elliptical-like nucleus surrounded by an extensive envelope.

cD galaxies. - Outstandingly large, luminous D galaxies, as observed on ordinary photographs. The nuclei may be single, double, or multiple.


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