1. In which Hubble types of galaxies are new stars most commonly forming? Describe the observational evidence that supports your answer. 2. What is the difference between a flocculent spiral galaxy...

1. In which Hubble types of galaxies are new stars most commonly forming? Describe the observational evidence that supports your answer.

2. What is the difference between a flocculent spiral galaxy and a grand-design spiral galaxy?

3. Briefly describe how the theory of self-propagating star formation accounts for the existence of spiral arms in some spiral galaxies.