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Trends along Hubble Sequence
•Roberts & Haynes 1994:
–Masses from S0 to Scd roughly constant, then decrease, and M/L roughly the same (recall these are all primarily luminous massive galaxies – why?)
–H I not significant in ellipticals (< 1 in 10000), but is in spirals (0.01 to 0.15 from Sa to Sm)
–Total surface density decreases, H I surface density increases
–Ellipticals are red, spirals are blue…
–H II regions frequency increases monotonically along the sequence (Kennicutt et al. 1989)
•Star formation rates appear key to these relations
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