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

For a PDF version of the article, click here.


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.


Table of Contents

INTRODUCTION

THE "BRIGHTEST GALAXY" MORPHOLOGY

THE OBSERVATIONS

DISCUSSION

THE SIGNIFICANCE OF TYPES I AND II

CONCLUSION

REFERENCES

For a postscript version of the article, click here.

Next