Question 1

Hubble Space Telescope observations have shown that when the mass of the central black hole is very large,then

Accepted Answer

A) the mass of the halo and disk of the host galaxy is also very large. 
B) the host galaxy is eventually completely consumed by the black hole. 
C) the galaxy is always a spiral galaxy. 
D) the mass of the bulge of the host galaxy is also very large. 
A) the mass of the halo and disk of the host galaxy is also very large. 
B) the host galaxy is eventually completely consumed by the black hole. 
C) the galaxy is always a spiral galaxy. 
D) the mass of the bulge of the host galaxy is also very large.

Question 2

Galaxy mergers take hundreds of millions of years to complete.

Accepted Answer

A) True 
 B)False

Question 3

Which of the following processes slowed the collapse of protogalactic clouds?

Accepted Answer

A) the formation of the first generation of stars 
B) the conversion of gravitational potential energy into kinetic and thermal energy as the cloud collapsed 
C) the shock waves from the exploding supernovae of the earliest stars 
D) the pull of gravity of the mass of the cloud material 
E) the radiating away of thermal energy 
A) the formation of the first generation of stars 
B) the conversion of gravitational potential energy into kinetic and thermal energy as the cloud collapsed 
C) the shock waves from the exploding supernovae of the earliest stars 
D) the pull of gravity of the mass of the cloud material 
E) the radiating away of thermal energy

Question 4

We can study how galaxies evolve because

Accepted Answer

A) galaxies are transparent to visible light. 
B) we are really smart astronomers. 
C) we can watch as they interact in real time. 
D) the farther away we look,the further back in time we see. 
A) galaxies are transparent to visible light. 
B) we are really smart astronomers. 
C) we can watch as they interact in real time. 
D) the farther away we look,the further back in time we see.

Question 5

What evidence supports the theory that elliptical galaxies come from denser clouds?

Accepted Answer

A) Elliptical galaxies are denser than spiral galaxies. 
B) Elliptical galaxies are generally larger than spiral galaxies. 
C) Elliptical galaxies at high redshifts lack young,blue stars. 
D) Elliptical galaxies have more gas than spiral galaxies. 
E) Elliptical galaxies have denser stars than spiral galaxies. 
A) Elliptical galaxies are denser than spiral galaxies. 
B) Elliptical galaxies are generally larger than spiral galaxies. 
C) Elliptical galaxies at high redshifts lack young,blue stars. 
D) Elliptical galaxies have more gas than spiral galaxies. 
E) Elliptical galaxies have denser stars than spiral galaxies.

Question 6

If we represent the Milky Way Galaxy as the size of a grapefruit (10-cm diameter),the distance to the Andromeda Galaxy would be about

Accepted Answer

A) 10 cm. 
B) 3 m. 
C) 30 m. 
D) 1 km. 
E) 100 km. 
A) 10 cm. 
B) 3 m. 
C) 30 m. 
D) 1 km. 
E) 100 km.

Question 7

Why should galaxy collisions have been more common in the past than they are today?

Accepted Answer

A) Galaxies were closer together in the past because the universe was smaller. 
B) Galaxies were more active in the past and therefore would have collided with each other more frequently. 
C) Galaxies were much bigger in the past since they had not contracted completely. 
D) Galaxies attracted each other more strongly in the past because they were more massive;they had not yet turned most of their mass into stars. 
A) Galaxies were closer together in the past because the universe was smaller. 
B) Galaxies were more active in the past and therefore would have collided with each other more frequently. 
C) Galaxies were much bigger in the past since they had not contracted completely. 
D) Galaxies attracted each other more strongly in the past because they were more massive;they had not yet turned most of their mass into stars.

Question 8

Which of the following is not a piece of evidence supporting the conclusion that active galactic nuclei are powered by accretion disks around supermassive black holes?

Accepted Answer

A) Observed radiation from the galactic center varies significantly in brightness in times as short as a few days. 
B) Infrared observations show that many stars are forming near the centers of active galaxies. 
C) Radio observations sometimes show long jets of material extending millions of light-years out from the galactic center. 
D) The total amount of radiation coming from the galactic center is,in some cases,comparable to the amount of radiation put out by 10 billion or more ordinary stars. 
E) Spectral lines from the galactic center indicate that clouds of gas are orbiting a central object at very high speed. 
A) Observed radiation from the galactic center varies significantly in brightness in times as short as a few days. 
B) Infrared observations show that many stars are forming near the centers of active galaxies. 
C) Radio observations sometimes show long jets of material extending millions of light-years out from the galactic center. 
D) The total amount of radiation coming from the galactic center is,in some cases,comparable to the amount of radiation put out by 10 billion or more ordinary stars. 
E) Spectral lines from the galactic center indicate that clouds of gas are orbiting a central object at very high speed.

Question 9

The mass of a supermassive black hole thought to power a typical bright active galactic nucleus is roughly

Accepted Answer

A) 3 solar masses. 
B) 10 solar masses. 
C) 1 trillion solar masses. 
D) 1 billion solar masses. 
A) 3 solar masses. 
B) 10 solar masses. 
C) 1 trillion solar masses. 
D) 1 billion solar masses.

Question 10

13)According to the theory that active galactic nuclei are powered by supermassive black holes,the high luminosity of an active galactic nucleus primarily consists of

Accepted Answer

A) light emitted by hot gas in an accretion disk that swirls around the black hole. 
B) intense radiation emitted by the black hole itself. 
C) the combined light of thousands of young,high-mass stars that orbit the black hole. 
D) radio waves emitted from radio lobes found on either side of the galaxy we see in visible light. 
A) light emitted by hot gas in an accretion disk that swirls around the black hole. 
B) intense radiation emitted by the black hole itself. 
C) the combined light of thousands of young,high-mass stars that orbit the black hole. 
D) radio waves emitted from radio lobes found on either side of the galaxy we see in visible light.

Question 11

What evidence supports the idea that a collision between two spiral galaxies might lead to the creation of a single elliptical galaxy?

Accepted Answer

A) observations of some elliptical galaxies surrounded by shells of stars that probably formed from stars stripped out of smaller galaxies 
B) the fact that elliptical galaxies dominate the galaxy populations at the cores of dense clusters of galaxies 
C) observations of some elliptical galaxies with stars and gas clouds in their cores that orbit differently from the other stars in the galaxy 
D) observations of giant elliptical galaxies at the center of dense clusters that may have grown by consuming other galaxies 
E) all of the above 
A) observations of some elliptical galaxies surrounded by shells of stars that probably formed from stars stripped out of smaller galaxies 
B) the fact that elliptical galaxies dominate the galaxy populations at the cores of dense clusters of galaxies 
C) observations of some elliptical galaxies with stars and gas clouds in their cores that orbit differently from the other stars in the galaxy 
D) observations of giant elliptical galaxies at the center of dense clusters that may have grown by consuming other galaxies 
E) all of the above

Question 12

Explain why galaxy interactions are far more common than star-star interactions.

Accepted Answer

Galaxies are much closer together,relati

Question 13

The most active galactic nuclei are usually found at large distances from us;relatively few nearby galaxies have active galactic nuclei.What does this imply?

Accepted Answer

A) Supermassive black holes existed only when the universe was young and no longer exist today. 
B) Active galactic nuclei tend to become less active as they age. 
C) Active galactic nuclei can form only at large distances from the Milky Way. 
D) The jets seen in many active galactic nuclei must cause them to move far away from us. 
A) Supermassive black holes existed only when the universe was young and no longer exist today. 
B) Active galactic nuclei tend to become less active as they age. 
C) Active galactic nuclei can form only at large distances from the Milky Way. 
D) The jets seen in many active galactic nuclei must cause them to move far away from us.

Question 14

A protogalactic cloud with very little angular momentum is more likely to form an elliptical galaxy than a spiral galaxy.

Accepted Answer

A) True 
 B)False

Question 15

A few decades ago,there was great controversy among astronomers over the question of quasar distances,with some arguing that quasars are much nearer than application of Hubble's law would seem to imply.Why do nearly all astronomers now agree that quasars really are quite far away?

Accepted Answer

A) We now have images and spectra that show quasars to be embedded at the centers of distant galaxies and within distant galaxy clusters. 
B) All quasars have large redshifts. 
C) Now that we can explain bright quasar emission with power due to the presence of supermassive black holes,there is no reason to doubt that quasars are far away. 
D) No one could think of a way to explain quasar speeds if they are nearby,so we concluded they must be far away. 
A) We now have images and spectra that show quasars to be embedded at the centers of distant galaxies and within distant galaxy clusters. 
B) All quasars have large redshifts. 
C) Now that we can explain bright quasar emission with power due to the presence of supermassive black holes,there is no reason to doubt that quasars are far away. 
D) No one could think of a way to explain quasar speeds if they are nearby,so we concluded they must be far away.

Question 16

Current understanding holds that a galaxy's type (spiral,elliptical,or irregular)

Accepted Answer

A) is always determined by the angular momentum of the protogalactic cloud that formed it. 
B) may either be the result of conditions in the protogalactic cloud that formed it or the result of later interactions with other galaxies. 
C) is determined by whether the galaxy is located in a cluster where collisions are likely or outside a cluster where collisions are less likely. 
D) may either be a result of the mass of the protogalactic cloud that formed it or the result of the heavy element abundance in that cloud. 
A) is always determined by the angular momentum of the protogalactic cloud that formed it. 
B) may either be the result of conditions in the protogalactic cloud that formed it or the result of later interactions with other galaxies. 
C) is determined by whether the galaxy is located in a cluster where collisions are likely or outside a cluster where collisions are less likely. 
D) may either be a result of the mass of the protogalactic cloud that formed it or the result of the heavy element abundance in that cloud.

Question 17

According to observations,what type of galaxy was much more common when the universe was 2 billion years old?

Accepted Answer

A) elliptical galaxies 
B) spiral galaxies 
C) irregular galaxies 
D) We can't say,because we are living at a time when the universe is 14 billion years old,not 2 billion years. 
A) elliptical galaxies 
B) spiral galaxies 
C) irregular galaxies 
D) We can't say,because we are living at a time when the universe is 14 billion years old,not 2 billion years.

Question 18

Galaxy collisions were more common in the past.

Accepted Answer

A) True 
 B)False

Question 19

How do observations of distant galaxies help us learn about galaxy evolution?

Accepted Answer

A) Observations at different distances show galaxies of different ages and therefore different stages of evolution. 
B) We can observe the birth of galaxies. 
C) We can observe the evolution of a single galaxy over time. 
D) We can observe two galaxies merging and what the result is,helping us learn how mergers affect evolution. 
E) We can see what our galaxy used to look like and therefore theorize about the physical processes that led to its current appearance. 
A) Observations at different distances show galaxies of different ages and therefore different stages of evolution. 
B) We can observe the birth of galaxies. 
C) We can observe the evolution of a single galaxy over time. 
D) We can observe two galaxies merging and what the result is,helping us learn how mergers affect evolution. 
E) We can see what our galaxy used to look like and therefore theorize about the physical processes that led to its current appearance.

Question 20

According to the theory that active galactic nuclei are powered by supermassive black holes,the energy released as light comes from

Accepted Answer

A) nuclear fusion in the accretion disk surrounding the black hole. 
B) gravitational potential energy released by matter that is falling toward the black hole. 
C) matter-antimatter annihilation occurring just outside the event horizon of the black hole. 
D) jets emerging from the accretion disk. 
A) nuclear fusion in the accretion disk surrounding the black hole. 
B) gravitational potential energy released by matter that is falling toward the black hole. 
C) matter-antimatter annihilation occurring just outside the event horizon of the black hole. 
D) jets emerging from the accretion disk.

Exam 21: Galaxy Evolution

Hubble Space Telescope observations have shown that when the mass of the central black hole is very large,then

Galaxy mergers take hundreds of millions of years to complete.

Which of the following processes slowed the collapse of protogalactic clouds?

We can study how galaxies evolve because

What evidence supports the theory that elliptical galaxies come from denser clouds?

If we represent the Milky Way Galaxy as the size of a grapefruit (10-cm diameter),the distance to the Andromeda Galaxy would be about

Why should galaxy collisions have been more common in the past than they are today?

Which of the following is not a piece of evidence supporting the conclusion that active galactic nuclei are powered by accretion disks around supermassive black holes?

The mass of a supermassive black hole thought to power a typical bright active galactic nucleus is roughly

13)According to the theory that active galactic nuclei are powered by supermassive black holes,the high luminosity of an active galactic nucleus primarily consists of

What evidence supports the idea that a collision between two spiral galaxies might lead to the creation of a single elliptical galaxy?

Explain why galaxy interactions are far more common than star-star interactions.

The most active galactic nuclei are usually found at large distances from us;relatively few nearby galaxies have active galactic nuclei.What does this imply?

A protogalactic cloud with very little angular momentum is more likely to form an elliptical galaxy than a spiral galaxy.

A few decades ago,there was great controversy among astronomers over the question of quasar distances,with some arguing that quasars are much nearer than application of Hubble's law would seem to imply.Why do nearly all astronomers now agree that quasars really are quite far away?

Current understanding holds that a galaxy's type (spiral,elliptical,or irregular)

According to observations,what type of galaxy was much more common when the universe was 2 billion years old?

Galaxy collisions were more common in the past.

How do observations of distant galaxies help us learn about galaxy evolution?

According to the theory that active galactic nuclei are powered by supermassive black holes,the energy released as light comes from

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