Approximately __________ of Spiral Galaxies Are Barred

Q2: More luminous giant galaxies tend to have

Q21: How have astronomers searched for evidence of

Q22: In most galaxies, the amount of dark

Q23: What is the connection between active galaxies

Q24: Elliptical galaxies have the shapes they do

Q27: If elliptical galaxies do not have cold

Q28: Active star formation does not occur in

Q29: Spiral structure can be triggered in a

Q30: Which of the following would NOT be

Q31: The three-dimensional shape of _ is set