Published in PASP 69, 1957.


A SPECTRAL CLASSIFICATION OF GALAXIES *

W. W. Morgan & N. U. Mayall


Lick Observatory, University of California


Table of Contents

INTRODUCTION

GENERAL CHARACTERISTICS OF THE SPECTRA OF GALAXIES
Humason's Spectral Classification System
Criteria for a Spectroscopic Classification of Galaxies

THE SPECTRUM OF THE ANDROMEDA NEBULA (M 31)
The Spectrum of the Nuclear Region
A Hypothetical H-R Diagram for the Inner Region
The Spectrum of the Main Body
A Comparison of the Spectra of M 31 and M 33

SPECTRA OF IRREGULAR GALAXIES LIKE THE LARGE MAGELLANIC CLOUD

A SPECTRAL CLASSIFICATION OF GALAXIES
The A-systems
The AF-Systems
The F-Systems
The FG-Systems
The K-Systems

THE RELATIONSHIP BETWEEN FORM AND SPECTRUM

A POSSIBLE LUMINOSITY EFFECT IN THE SPECTRA OF THE K-SYSTEMS

CONCLUSION

REFERENCES



* Contributions from the Lick Observatory, Ser. II, No. 79.

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