Question 1

Telescopes being planned for the study of the earliest stages in galactic lives will be optimized for observations in

Accepted Answer

A) visible light. 
B) infrared light. 
C) radio waves. 
D) X-rays. 
A) visible light. 
B) infrared light. 
C) radio waves. 
D) X-rays.

Question 2

Why are telescopes sometimes called "time machines"?

Accepted Answer

A) because the author,H.G.Wells,used the term to describe telescopes in a book 
B) because some of the oldest telescopes are still in use today 
C) because observations of distant objects reveal them as they were in the past 
D) because astronomers can use telescopes to see the Milky Way as it was when it was much younger 
E) It's a journalistic misnomer: you cannot travel into the past or the future. 
A) because the author,H.G.Wells,used the term to describe telescopes in a book 
B) because some of the oldest telescopes are still in use today 
C) because observations of distant objects reveal them as they were in the past 
D) because astronomers can use telescopes to see the Milky Way as it was when it was much younger 
E) It's a journalistic misnomer: you cannot travel into the past or the future.

Question 3

According to current understanding,what is a quasar?

Accepted Answer

A) an active galactic nucleus that is particularly bright 
B) a very large galaxy thought to be formed by the merger of several smaller galaxies,typically found in the center of a galaxy cluster 
C) any object with an extremely large redshift is called a quasar 
D) a galaxy with an unusually high rate of star formation 
A) an active galactic nucleus that is particularly bright 
B) a very large galaxy thought to be formed by the merger of several smaller galaxies,typically found in the center of a galaxy cluster 
C) any object with an extremely large redshift is called a quasar 
D) a galaxy with an unusually high rate of star formation

Question 4

What are the typical features seen in quasar absorption lines of intergalactic clouds?

Accepted Answer

A) The hydrogen line is wider and lines from heavy elements are weaker at higher redshifts. 
B) The hydrogen line is narrower and lines from heavy elements are weaker at higher redshifts. 
C) The hydrogen line is wider and lines from heavy elements are stronger at higher redshifts. 
D) The hydrogen line is narrower and lines from heavy elements are stronger at higher redshifts. 
E) A few weak absorption lines are always seen at higher redshift than the quasar. 
A) The hydrogen line is wider and lines from heavy elements are weaker at higher redshifts. 
B) The hydrogen line is narrower and lines from heavy elements are weaker at higher redshifts. 
C) The hydrogen line is wider and lines from heavy elements are stronger at higher redshifts. 
D) The hydrogen line is narrower and lines from heavy elements are stronger at higher redshifts. 
E) A few weak absorption lines are always seen at higher redshift than the quasar.

Question 5

How does a starburst end? What might happen to the galaxy afterwards?

Accepted Answer

A starburst might end by simply using up

Question 6

Process of Science: Explain how we can use telescopes as time machines to directly test theories of galaxy formation.

Accepted Answer

Telescopes see objects as they were when

Question 7

Why do we believe that starburst galaxies represent a temporary stage in galaxy evolution?

Accepted Answer

A) We observe starbursts to last only a few years at a time. 
B) Such galaxies produce so much light that they would have consumed all their gas long ago if they had always been forming stars at this high rate. 
C) We don't see any nearby starburst galaxies. 
D) All starburst galaxies look like normal spiral galaxies,aside from the starbursts. 
A) We observe starbursts to last only a few years at a time. 
B) Such galaxies produce so much light that they would have consumed all their gas long ago if they had always been forming stars at this high rate. 
C) We don't see any nearby starburst galaxies. 
D) All starburst galaxies look like normal spiral galaxies,aside from the starbursts.

Question 8

Most active galactic nuclei are found at large distances from us,with relatively few nearby.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 can form only at large distances from the Milky Way. 
C) Active galactic nuclei exist tend to become less active as they age. 
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 can form only at large distances from the Milky Way. 
C) Active galactic nuclei exist tend to become less active as they age. 
D) The jets seen in many active galactic nuclei must cause them to move far away from us.

Question 9

How do we know that there are intergalactic clouds between a distant quasar and us?

Accepted Answer

A) We see hydrogen emission lines at redshifts smaller than that of the quasar. 
B) We see hydrogen absorption lines at redshifts smaller than that of the quasar. 
C) We see hydrogen emission lines at redshifts greater than that of the quasar. 
D) We see hydrogen absorption lines at redshifts greater than that of the quasar. 
E) We see that the emission lines from the quasar are lessened by intervening gas and dust. 
A) We see hydrogen emission lines at redshifts smaller than that of the quasar. 
B) We see hydrogen absorption lines at redshifts smaller than that of the quasar. 
C) We see hydrogen emission lines at redshifts greater than that of the quasar. 
D) We see hydrogen absorption lines at redshifts greater than that of the quasar. 
E) We see that the emission lines from the quasar are lessened by intervening gas and dust.

Question 10

Which of the following is an important starting assumption in models of galaxy formation?

Accepted Answer

A) Galaxies form first,then black holes. 
B) All galaxies start out as spiral galaxies. 
C) Black holes form first,seeding the formation of galaxies. 
D) Some regions in the universe start out denser than others. 
A) Galaxies form first,then black holes. 
B) All galaxies start out as spiral galaxies. 
C) Black holes form first,seeding the formation of galaxies. 
D) Some regions in the universe start out denser than others.

Question 11

Central black holes can be very efficient for converting the mass-energy of infalling matter to thermal energy in the accretion disk.Roughly what percentage of the mass-energy can be converted to other forms of energy as matter falls into a black hole?

Accepted Answer

A) 0.7% 
B) 1% - 4% 
C) 10 - 40% 
D) 100% 
A) 0.7% 
B) 1% - 4% 
C) 10 - 40% 
D) 100%

Question 12

How many more stars does a starburst galaxy form,in one year,than the Milky Way?

Accepted Answer

A) a few 
B) about ten 
C) about a hundred 
D) about a thousand 
E) about the same,but it does so for much longer 
A) a few 
B) about ten 
C) about a hundred 
D) about a thousand 
E) about the same,but it does so for much longer

Question 13

I observe a galaxy that is 100 million light-years away: what do I see?

Accepted Answer

A) the light from the galaxy as it is today,but it is blueshifted 
B) the light from the galaxy as it is today,but it is redshifted 
C) the light from the galaxy as it was 100 million years ago and it it blueshifted 
D) the light from the galaxy as it was 100 million years ago and it is redshifted 
E) Nothing: the galaxy lies beyond the cosmological horizon. 
A) the light from the galaxy as it is today,but it is blueshifted 
B) the light from the galaxy as it is today,but it is redshifted 
C) the light from the galaxy as it was 100 million years ago and it it blueshifted 
D) the light from the galaxy as it was 100 million years ago and it is redshifted 
E) Nothing: the galaxy lies beyond the cosmological horizon.

Question 14

Collisions between galaxies typically unfold over a period of

Accepted Answer

A) several days. 
B) several months. 
C) thousands of years. 
D) hundreds of millions of years. 
A) several days. 
B) several months. 
C) thousands of years. 
D) hundreds of millions of years.

Question 15

If an object doubles its luminosity in 10 hours,how large can the emitting source of light be?

Accepted Answer

A) about 10 light-years across 
B) about 10 parsecs across 
C) about 10 light-hours across 
D) varies depending on how luminous the object is 
E) varies depending on how far away the object is 
A) about 10 light-years across 
B) about 10 parsecs across 
C) about 10 light-hours across 
D) varies depending on how luminous the object is 
E) varies depending on how far away the object is

Question 16

Observations of quasar absorption lines show that intergalactic clouds were more common in the past.

Accepted Answer

A) True 
 B)False

Question 17

What information about protogalactic gas clouds is contained in quasar absorption lines?

Accepted Answer

Quasar absorption lines show the presenc

Question 18

Which of the following is not true of quasars?

Accepted Answer

A) Some quasars are more than a thousand times more luminous than the Milky Way. 
B) Quasars were more common in the past. 
C) Quasars are powered by the energy radiated by matter falling into a central black hole. 
D) Quasars are powered by the intense production of large numbers of stars that can only be sustained for a relatively short time. 
E) Some quasars can change their brightness every few hours. 
A) Some quasars are more than a thousand times more luminous than the Milky Way. 
B) Quasars were more common in the past. 
C) Quasars are powered by the energy radiated by matter falling into a central black hole. 
D) Quasars are powered by the intense production of large numbers of stars that can only be sustained for a relatively short time. 
E) Some quasars can change their brightness every few hours.

Question 19

Briefly explain how we think quasars produce so much energy.

Accepted Answer

The energy is produc

Question 20

Which of the following cannot be true of the very first stars formed in the Universe?

Accepted Answer

A) They may have all exploded as supernovae by now. 
B) They may have formed in large clusters. 
C) They may have formed singly,in isolation. 
D) Some may still exist in the Milky Way today. 
E) They may have had rocky planets around them. 
A) They may have all exploded as supernovae by now. 
B) They may have formed in large clusters. 
C) They may have formed singly,in isolation. 
D) Some may still exist in the Milky Way today. 
E) They may have had rocky planets around them.

Exam 21: Galaxy Evolution

Telescopes being planned for the study of the earliest stages in galactic lives will be optimized for observations in

Why are telescopes sometimes called "time machines"?

According to current understanding,what is a quasar?

What are the typical features seen in quasar absorption lines of intergalactic clouds?

How does a starburst end? What might happen to the galaxy afterwards?

Process of Science: Explain how we can use telescopes as time machines to directly test theories of galaxy formation.

Why do we believe that starburst galaxies represent a temporary stage in galaxy evolution?

Most active galactic nuclei are found at large distances from us,with relatively few nearby.What does this imply?

How do we know that there are intergalactic clouds between a distant quasar and us?

Which of the following is an important starting assumption in models of galaxy formation?

Central black holes can be very efficient for converting the mass-energy of infalling matter to thermal energy in the accretion disk.Roughly what percentage of the mass-energy can be converted to other forms of energy as matter falls into a black hole?

How many more stars does a starburst galaxy form,in one year,than the Milky Way?

I observe a galaxy that is 100 million light-years away: what do I see?

Collisions between galaxies typically unfold over a period of

If an object doubles its luminosity in 10 hours,how large can the emitting source of light be?

Observations of quasar absorption lines show that intergalactic clouds were more common in the past.

What information about protogalactic gas clouds is contained in quasar absorption lines?

Which of the following is not true of quasars?

Briefly explain how we think quasars produce so much energy.

Which of the following cannot be true of the very first stars formed in the Universe?

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