Question

question 15
1 pts
what is the difference between an sbb galaxy and an sb galaxy?
the sbb galaxy has less tightly wound sprial arms than the sb galaxy.
the sbb galaxy is more elliptical than the sb galaxy.
the sbb galaxy has more tightly wound spiral arms than the sb galaxy.
the sbb galaxy is an irregular galaxy but the sb galaxy is not.
the sbb galaxy has a bar of material passing though the center and the sb galaxy does not.

Explanation:

In the Hubble sequence, spiral galaxies are categorized by the presence of a central bar: "S" denotes unbarred spirals, and "SB" denotes barred spirals. The lowercase letter (e.g., b) indicates the tightness of spiral arms (consistent for both Sb and SBb). Thus, the key difference is the central bar in SBb galaxies that Sb galaxies lack.

Answer:

The SBb galaxy has a bar of material passing though the center and the Sb galaxy does not.