Exam 13: The Galaxies

In which direction do galaxies evolve on the Hubble "tuning fork" classification scheme and what is the evolutionary significance of this diagram,shown in Figure 13-33 of Comins,Discovering the Essential Universe,6th ed.?

The rotation curve of a galaxy is a graph showing the galaxy's speed of rotation at different distances from the center.The observed rotation curve in the outer parts of a typical large spiral galaxy:

Which occurrence has NOT been observed as evidence of colliding galaxies?

A rotation curve is a plot of the rotational velocity of a galaxy as a function of the distance away from the galactic center.What does the rotation curve of the Milky Way Galaxy look like?

How are superclusters spread throughout the universe?

What is an E3 galaxy?

When the jet of an active galaxy is aimed directly at Earth,we see the object as a:

The Local Supercluster of galaxies is also known as the:

Which objects do we NOT find in orbit around the galactic center?

Spiral density waves move through a medium that is also moving.The speed of the density waves:

Quasars emit significant amounts of radiation from the Lyman α transition.When the spectrum is observed on Earth,it is found that the Lyman α line is accompanied by many absorption lines,called the Lyman α forest.What is the origin of these lines? (See Figure 13-57,Comins,Discovering the Essential Universe,6th ed.)

A rich,regular cluster of galaxies differs from a rich,irregular cluster in that:

The event that settled the Shapley-Curtis debate about "spiral nebulae" was:

What are the Magellanic Clouds?

The plane of our Galaxy is filled with clouds of gas and dust.To receive information from objects embedded in these clouds,astronomers use receivers sensitive in the following ranges EXCEPT:

What is a poor cluster of galaxies?

The period-luminosity relationship for Cepheid variable stars,relating variability to absolute overall brightness,thereby providing identifiable beacons throughout our local space,was discovered by:

In order to emit a 21-cm photon,an atom of neutral hydrogen in interstellar space must absorb energy to place it in the excited state (the parallel spin configuration).What is the MOST likely mechanism to achieve this?

To an astronomer,what is a "standard candle"?

Why is it that we rely upon the 21-cm line associated with the spin flip in hydrogen and not the more familiar hydrogen Balmer lines to gather information from the far side of the galactic plane?