Question 1

Where are the X-rays produced that are emitted by quasars and other active galactic nuclei?

Accepted Answer

A) in hot gas in an accretion disk around a central black hole 
B) in ionization nebulae of interstellar gas that surround the accretion disk 
C) in dust grains in molecular clouds that encircle the active galactic nucleus 
D) in fast-moving electrons that jet from the active galactic nucleus 
E) all of the above 
A) in hot gas in an accretion disk around a central black hole 
B) in ionization nebulae of interstellar gas that surround the accretion disk 
C) in dust grains in molecular clouds that encircle the active galactic nucleus 
D) in fast-moving electrons that jet from the active galactic nucleus 
E) all of the above

Question 2

Some galaxies in the Local Group stopped forming stars for several billion years but then started again.

Accepted Answer

A) True 
 B)False

Question 3

What is a galactic wind?

Accepted Answer

A) a jet of ionized particles shot out of a starburst galaxy 
B) hot gas erupting into intergalactic space from a large superbubble 
C) the heat (infrared radiation)emitted by dust grains in the large molecular clouds of starburst galaxies 
D) the cooler gas pushed out of a starburst galaxy by the intense radiation pressure 
E) a wind created by the expansion of the universe that can move galaxies around 
A) a jet of ionized particles shot out of a starburst galaxy 
B) hot gas erupting into intergalactic space from a large superbubble 
C) the heat (infrared radiation)emitted by dust grains in the large molecular clouds of starburst galaxies 
D) the cooler gas pushed out of a starburst galaxy by the intense radiation pressure 
E) a wind created by the expansion of the universe that can move galaxies around

Question 4

What is a central dominant galaxy?

Accepted Answer

A) a galaxy around which many other smaller galaxies orbit 
B) a giant spiral galaxy that exerts large tidal forces on other nearby galaxies 
C) a spiral galaxy from which many smaller galaxies form when it is stripped apart by tidal forces 
D) a giant elliptical galaxy at the center of a dense cluster 
E) a hypothesized galaxy type that no longer exists but once dominated the structure of the universe 
A) a galaxy around which many other smaller galaxies orbit 
B) a giant spiral galaxy that exerts large tidal forces on other nearby galaxies 
C) a spiral galaxy from which many smaller galaxies form when it is stripped apart by tidal forces 
D) a giant elliptical galaxy at the center of a dense cluster 
E) a hypothesized galaxy type that no longer exists but once dominated the structure of the universe

Question 5

Interactions among galaxies also are thought to influence a galaxy's type in at least some cases.Which of the following does not support the idea that interactions can shape galaxies?

Accepted Answer

A) the fact that more distant galaxies have larger redshifts 
B) computer modeling of collisions between galaxies 
C) the fact that galaxies with distorted appearances are more common at great distances than nearby 
D) the presence of features such as "tails" extending out of galaxies,bridges between galaxies,and rings of stars around galaxies 
A) the fact that more distant galaxies have larger redshifts 
B) computer modeling of collisions between galaxies 
C) the fact that galaxies with distorted appearances are more common at great distances than nearby 
D) the presence of features such as "tails" extending out of galaxies,bridges between galaxies,and rings of stars around galaxies

Question 6

Give several observations supporting the idea that the high redshifts of quasars really do imply great distances.

Accepted Answer

(a)We see many quasars with high redshif

Question 7

What evidence suggests that small galaxies in our Local Group have undergone two or more starbursts in the past?

Accepted Answer

A) We observe several small galaxies currently undergoing massive star formation. 
B) We see small galaxies in which many stars have one age and many others have another age that is billions of years older. 
C) We see evidence that small galaxies in our Local Group have experienced several collisions in the past. 
D) We see evidence that several small galaxies were shot out of larger galaxies in our Local Group during an age of starburst activity. 
E) We do not have any evidence that galaxies in our Local Group were once starburst galaxies. 
A) We observe several small galaxies currently undergoing massive star formation. 
B) We see small galaxies in which many stars have one age and many others have another age that is billions of years older. 
C) We see evidence that small galaxies in our Local Group have experienced several collisions in the past. 
D) We see evidence that several small galaxies were shot out of larger galaxies in our Local Group during an age of starburst activity. 
E) We do not have any evidence that galaxies in our Local Group were once starburst galaxies.

Question 8

Which of the following types of protogalactic clouds is most likely to form a spiral galaxy?

Accepted Answer

A) a very low-density cloud with very little angular momentum 
B) a dense cloud with very little angular momentum 
C) a low-density cloud with quite a bit of angular momentum 
D) a dense cloud with quite a bit of angular momentum 
E) a very massive cloud with any density and a lot of angular momentum 
A) a very low-density cloud with very little angular momentum 
B) a dense cloud with very little angular momentum 
C) a low-density cloud with quite a bit of angular momentum 
D) a dense cloud with quite a bit of angular momentum 
E) a very massive cloud with any density and a lot of angular momentum

Question 9

Which of the following types of protogalactic clouds is most likely to form an elliptical galaxy?

Accepted Answer

A) a very low-density cloud with very little angular momentum 
B) a dense cloud with very little angular momentum 
C) a low-density cloud with quite a bit of angular momentum 
D) a dense cloud with quite a bit of angular momentum 
E) a very massive cloud with any density and a lot of angular momentum 
A) a very low-density cloud with very little angular momentum 
B) a dense cloud with very little angular momentum 
C) a low-density cloud with quite a bit of angular momentum 
D) a dense cloud with quite a bit of angular momentum 
E) a very massive cloud with any density and a lot of angular momentum

Question 10

A protogalactic cloud with slow star formation is more likely to form a spiral galaxy than an elliptical galaxy.

Accepted Answer

A) True 
 B)False

Question 11

Which of the following is not a strong argument for the theory that some large elliptical galaxies formed as the result of galaxy collisions?

Accepted Answer

A) Elliptical galaxies dominate the population in dense galaxy clusters. 
B) Some ellipticals have stars and gas that rotate opposite to the rest of the galaxy. 
C) Some elliptical galaxies are surrounded by shells of stars. 
D) Computer simulations predict that the product of a galaxy collision is generally an elliptical galaxy. 
E) Galaxy collisions are common and most galaxies in the universe are elliptical. 
A) Elliptical galaxies dominate the population in dense galaxy clusters. 
B) Some ellipticals have stars and gas that rotate opposite to the rest of the galaxy. 
C) Some elliptical galaxies are surrounded by shells of stars. 
D) Computer simulations predict that the product of a galaxy collision is generally an elliptical galaxy. 
E) Galaxy collisions are common and most galaxies in the universe are elliptical.

Question 12

Quasar spectra often show many absorption lines that all appear to be due to the same electron transition (such as level 1 to level 2 in hydrogen)but that fall at different wavelengths in the spectrum.Why do we think this is the case?

Accepted Answer

A) We are seeing absorption lines from clouds of gas that lie between us and the quasar,and therefore each cloud has a different redshift. 
B) Quasars are rotating rapidly,and this rotation produces spectral lines with a wide variety of Doppler shifts. 
C) The lines fall at different wavelengths because they are produced by different chemical elements. 
D) No one knows-it remains perhaps the greatest mystery about quasars. 
A) We are seeing absorption lines from clouds of gas that lie between us and the quasar,and therefore each cloud has a different redshift. 
B) Quasars are rotating rapidly,and this rotation produces spectral lines with a wide variety of Doppler shifts. 
C) The lines fall at different wavelengths because they are produced by different chemical elements. 
D) No one knows-it remains perhaps the greatest mystery about quasars.

Question 13

Starburst galaxies produce most of their light in the infrared.

Accepted Answer

A) True 
 B)False

Question 14

The observed relationship of 1/500 between the masses of central black holes and the bulge masses of galaxies implies that

Accepted Answer

A) the black hole will eventually suck in the rest of the galaxy. 
B) galaxy formation and supermassive black hole formation must be related somehow. 
C) the biggest galaxies have the most luminous quasars. 
D) quasars were more common 10 billion years ago than they are today. 
A) the black hole will eventually suck in the rest of the galaxy. 
B) galaxy formation and supermassive black hole formation must be related somehow. 
C) the biggest galaxies have the most luminous quasars. 
D) quasars were more common 10 billion years ago than they are today.

Question 15

In the 1960s,Maarten Schmidt determined that quasars were very distant objects by

Accepted Answer

A) determining how luminous they were. 
B) determining how small the source of light was from its variations in luminosity. 
C) discovering that they were embedded in distant galaxies. 
D) determining their redshifts. 
E) determining their parallax angles. 
A) determining how luminous they were. 
B) determining how small the source of light was from its variations in luminosity. 
C) discovering that they were embedded in distant galaxies. 
D) determining their redshifts. 
E) determining their parallax angles.

Question 16

Why do spiral galaxy mergers often trigger starbursts?

Accepted Answer

The dusty molecular clouds in spiral gal

Question 17

If the Andromeda Galaxy collided with the Milky Way,what would most likely happen to Earth?

Accepted Answer

A) The Sun and all its planets would be crushed by collisions with stars and planets from the Andromeda Galaxy. 
B) Nothing. 
C) The Sun would not be disturbed,but the solar system would be ripped apart. 
D) The Sun will turn into a red giant and explode. 
A) The Sun and all its planets would be crushed by collisions with stars and planets from the Andromeda Galaxy. 
B) Nothing. 
C) The Sun would not be disturbed,but the solar system would be ripped apart. 
D) The Sun will turn into a red giant and explode.

Question 18

Suppose we observe a source of X-rays that varies substantially in brightness over a period of a few days.What can we conclude?

Accepted Answer

A) The X-ray source is a quasar. 
B) The X-ray source contains a black hole with an accretion disk. 
C) The X-ray source is no more than a few light-days in diameter. 
D) The X-ray source must have a strong,rapidly varying magnetic field. 
A) The X-ray source is a quasar. 
B) The X-ray source contains a black hole with an accretion disk. 
C) The X-ray source is no more than a few light-days in diameter. 
D) The X-ray source must have a strong,rapidly varying magnetic field.

Question 19

The unusually bright centers found in some galaxies are called

Accepted Answer

A) active galactic nuclei. 
B) halos. 
C) supermassive black holes. 
D) starbursts. 
A) active galactic nuclei. 
B) halos. 
C) supermassive black holes. 
D) starbursts.

Question 20

Briefly explain why starburst galaxies appear fairly ordinary when they are observed in visible light but extraordinary when they are observed in infrared light.

Accepted Answer

Starburst galaxies are filled with star-

Exam 21: Galaxy Evolution

Where are the X-rays produced that are emitted by quasars and other active galactic nuclei?

Some galaxies in the Local Group stopped forming stars for several billion years but then started again.

What is a galactic wind?

What is a central dominant galaxy?

Interactions among galaxies also are thought to influence a galaxy's type in at least some cases.Which of the following does not support the idea that interactions can shape galaxies?

Give several observations supporting the idea that the high redshifts of quasars really do imply great distances.

What evidence suggests that small galaxies in our Local Group have undergone two or more starbursts in the past?

Which of the following types of protogalactic clouds is most likely to form a spiral galaxy?

Which of the following types of protogalactic clouds is most likely to form an elliptical galaxy?

A protogalactic cloud with slow star formation is more likely to form a spiral galaxy than an elliptical galaxy.

Which of the following is not a strong argument for the theory that some large elliptical galaxies formed as the result of galaxy collisions?

Quasar spectra often show many absorption lines that all appear to be due to the same electron transition (such as level 1 to level 2 in hydrogen)but that fall at different wavelengths in the spectrum.Why do we think this is the case?

Starburst galaxies produce most of their light in the infrared.

The observed relationship of 1/500 between the masses of central black holes and the bulge masses of galaxies implies that

In the 1960s,Maarten Schmidt determined that quasars were very distant objects by

Why do spiral galaxy mergers often trigger starbursts?

If the Andromeda Galaxy collided with the Milky Way,what would most likely happen to Earth?

Suppose we observe a source of X-rays that varies substantially in brightness over a period of a few days.What can we conclude?

The unusually bright centers found in some galaxies are called

Briefly explain why starburst galaxies appear fairly ordinary when they are observed in visible light but extraordinary when they are observed in infrared light.

A Modern View of the Universe

Discovering the Universe for Yourself

The Science of Astronomy

Making Sense of the Universe: Understanding Motion, Energy, and Gravity

Light and Matter: Reading Messages from the Cosmos

Telescopes: Portals of Discovery

Our Planetary System

Formation of the Solar System

Planetary Geology: Earth and the Other Terrestrial Worlds

Planetary Atmospheres: Earth and the Other Terrestrial Worlds

Jovian Planet Systems

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Other Planetary Systems: The New Science of Distant Worlds

Our Star

Surveying the Stars

Star Birth

Star Stuff

The Bizarre Stellar Graveyard

Our Galaxy

Galaxies and the Foundations of Modern Cosmology

The Birth of the Universe

Dark Matter, Dark Energy, and the Fate of the Universe

Life in the Universe

Celestial Timekeeping and Navigation

Space and Time

Spacetime and Gravity

Building Blocks of the Universe

Filters