•A
range of structural types (Oemler 1974)
–cD
clusters have 1 or 2 central dominant cD galaxies,
and no more than about 20% spirals, with a E: S0: S ratio of 3:
4: 2.
–Spiral-rich
clusters have E : S0 : S ratios more like
1: 2: 3 – about half spirals.
–Remainder
are spiral-poor clusters. No dominant cD
galaxy and typical ratio of 1: 2: 1.
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