Both studies showed that inner rings become smaller with advancing stage along the Hubble sequence and with fainter luminosity class. This shows that the largest inner rings and pseudorings are found in early-type barred spirals of high luminosity. This study gave a greater dependence on luminosity class than the formulation of Buta and de Vaucouleurs, but the difference may reflect differences in the sample characteristics and calibrating distances. Logarithmic means gave average diameters of 1.1, 9.5, and 22.4 kpc for nuclear, inner, and outer rings and pseudorings, respectively, in 20 SB galaxies. The diameters of rings in weakly barred and nonbarred galaxies were also considered, and found to show greater scatter.
Many galaxies possess both inner and outer rings simultaneously.
The co-existence of these features in the same galaxy provides a more dynamically interesting diameter ratio than those in equations 1 and 2. As noted by Athanassoula et al. The upper left panel is irrespective of family, while the other panels separate barred, weakly barred, and nonbarred galaxies. No evidence for a significant type dependence of these ratios was found. Weakly-barred and nonbarred galaxies displayed considerably more scatter and possible weak type dependences in the same ratios.