Published in PASP 70, 1958.
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Abstract. A revised system of classification of the forms of galaxies is described. The principal criterion of type is the degree of central concentration of the light of each galaxy; in this respect the new system can be considered a modification of that of Hubble.
The basis for the new classification is the spectroscopic work on composite spectra of galaxies by Morgan and Mayall. The correlation between form and stellar population found by these investigators has been utilized to set tip a form classification which would be indicative of the general kind of stellar population encountered in the majority of galaxies classified.
A total of 608 galaxies have been classified on the new system from plates obtained principally by Edwin Hubble in the Mount Wilson-Palomar collection.
Possible applications of the new classification to problems of galactic distribution and evolution are outlined. There is a definite indication of large-scale fluctuations in the average stellar population characteristics of galaxies within distances corresponding to redshifts of around 2000 km/sec.
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