Which of the following is true of double-lobed radio sources?
A) Their radio lobes are associated with interacting galaxies.
B) They are less active than normal galaxies.
C) Their nuclei are relatively cooler than their peripheries.
D) Their radio lobes are located at the end of their spiral arms.
Question 2The rotation curve method works:
A) only for galaxies near enough to be well resolved.
B) only for distant spiral galaxies.
C) only for elliptical galaxies.
D) for all galaxies, irrespective of their distance from Earth.
Question 3Which of the following information is required to compute the mass of a galaxy using the rotation curve method?
A) The age of the galaxy
B) The distance of the galaxy from the nearest rich galaxy cluster
C) The total number of stars in the galaxy
D) The true sizes of the orbits of stars or gas clouds within the galaxy
Question 4The average separation between galaxies is about _____ times their diameter.
A) 6
B) 20
C) 105
D) 1017
Question 5Which of the following is true of supermassive black holes?
A) They are found only in elliptical galaxies.
B) They are not found in Seyfert galaxies.
C) They can be triggered into eruptions because of tidal interactions.
D) They are not affected by tidal interactions between galaxies.
Question 6Active galaxy is a galaxy:
A) whose center emits large amounts of excess energy.
B) whose center does not have a black hole.
C) that is in the process of merging with another galaxy.
D) that manifests a blueshift instead of a redshift.
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