de Vaucouleurs Revised System |
The 3-D system. Principal axis is stage, vertical axis is bar, and the in-out axis is ring. The overall shape indicates the maximum variety occurs in the middle of the spiral sequence. (click to enlarge) |
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  Cut through the 3-D system near Sb; sketches to illustrate the features. |
  Ditto, with example galaxies inserted.
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Figures taken from deVaucouleurs 1959 article in Handbuch der Physik [o-link] |