Bar strengths of galaxies

In contrast, three physically distinct formation channels for S0/a galaxies are identified: (primeval S0)-to-S transitions; faded spiral galaxies; and, most commonly, wet-major-merger-built dust-rich S0 galaxies (on the 'green mountain'). Galaxies with particularly strong spirals appear on the right-hand side of the spiral galaxy distribution. Furthermore, a 'Dust Attrition/Retention' sequence places S0 (and compact massive ES,b) galaxies with dusty nuclear discs between the dust-poor and dust-rich S0 galaxies, and a 'Disc Down-sizing' sequence is revealed, in which E galaxies with dusty nuclear discs - potentially formed through 'damp' mergers - bridge the ES,e (ellicular) galaxies with intermediate-scale stellar discs and the dust-poor pure E galaxies.

Extensive historical context is provided, and, finally, suspected biases in precision cosmology stemming from neglected precision galaxy morphology are discussed.