What morphological characteristic defines an Sc galaxy compared to an Sa galaxy?

Answer

It has a relatively small central bulge and loosely wound, often fragmented arms

As the subtype letter increases from 'a' to 'c' in unbarred spirals, the system shifts from bulge-dominated to disk-dominated, meaning Sc galaxies exhibit smaller bulges and more loosely wound, sometimes flocculent, spiral arms.

What morphological characteristic defines an Sc galaxy compared to an Sa galaxy?
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