Question 1

We interpret the fact that we saw more AGNs in the past than we do today to indicate that

Accepted Answer

A)  there were fewer galaxy-galaxy interactions in the past. 
B)  there were more galaxy-galaxy interactions in the past. 
C)  supermassive black holes were larger in the past. 
D)  today's AGNs are primarily hidden by large amounts of cold gas and dust. 
A)  there were fewer galaxy-galaxy interactions in the past. 
B)  there were more galaxy-galaxy interactions in the past. 
C)  supermassive black holes were larger in the past. 
D)  today's AGNs are primarily hidden by large amounts of cold gas and dust.

Question 2

How do astronomers know that AGNs are as small as our Solar System?

Accepted Answer

AGNs have been observed to vary dramatic

Question 3

We know AGN are about the size of our Solar System because of imaging done with the Hubble Space Telescope.

Accepted Answer

A) True 
 B)False

Question 4

Give three examples of types of active galactic nuclei and give one reason why each is unique.

Accepted Answer

Three types of AGN: (1)Quasars-extremely

Question 5

In spiral galaxies,the size of the central bulge is correlated with the

Accepted Answer

A)  tightness of the spiral arms. 
B)  luminosity of the galaxy. 
C)  age of the galaxy. 
D)  thickness of the disk. 
A)  tightness of the spiral arms. 
B)  luminosity of the galaxy. 
C)  age of the galaxy. 
D)  thickness of the disk.

Question 6

What is the difference between a Seyfert galaxy and a normal spiral galaxy?

Accepted Answer

A Seyfert galaxy contains a ve

Question 7

Seyfert galaxies are unique because they have large lobes of radio emission that extend well beyond the visible part of the galaxy.

Accepted Answer

A) True 
 B)False

Question 8

AGNs appear to be powered by

Accepted Answer

A)  supermassive black holes. 
B)  extremely dense star clusters. 
C)  ultradense molecular clouds. 
D)  dark matter. 
A)  supermassive black holes. 
B)  extremely dense star clusters. 
C)  ultradense molecular clouds. 
D)  dark matter.

Question 9

Describe two ways by which spiral structure may be induced in a spiral galaxy's disk.

Accepted Answer

Possibilities are:
(1)gravitational inte

Question 10

If the radio lobes of a radio galaxy extend out to 10 Mpc from the center of the galaxy and the particles in them are traveling at approximately 0.99 c,then how long must the black hole at the center have been ejecting this material into space? Note that   and   .

Accepted Answer

Because @#IMG-DLM& ,the length

Question 11

If the average quasar has a luminosity of   and an absolute magnitude of -40 and you discover one that has an apparent magnitude of +9,then what is its distance?

Accepted Answer

A)  600 Mpc 
B)  200 Mpc 
C)  100 Mpc 
D)  50 Mpc 
A)  600 Mpc 
B)  200 Mpc 
C)  100 Mpc 
D)  50 Mpc

Question 12

More luminous giant galaxies tend to have __________ supermassive black holes at their centers.

Accepted Answer

A)  more massive 
B)  radio quiet 
C)  more luminous 
D)  slower rotating 
A)  more massive 
B)  radio quiet 
C)  more luminous 
D)  slower rotating

Question 13

In some radio galaxies,we only see one side of the jet because

Accepted Answer

A)  the black hole only produces a jet in one direction. 
B)  of relativistic beaming. 
C)  the other side is inside the black hole's event horizon. 
D)  of dust obscuration. 
A)  the black hole only produces a jet in one direction. 
B)  of relativistic beaming. 
C)  the other side is inside the black hole's event horizon. 
D)  of dust obscuration.

Question 14

Why do rotation curves of galaxies imply that dark matter exists?

Accepted Answer

A)  The velocity of stars rises dramatically at large distances from the centers of galaxies,implying large amounts of dark matter cause these stars to move much faster than stars at smaller distances. 
B)  The velocity of stars stays somewhat constant at distances beyond the visible edges of galaxies,implying that more matter than what we observe in stars and gas must be there. 
C)  The velocity of stars is low in the inner regions of galaxies,suggesting that dark matter is impeding their motion. 
D)  The velocity of stars rises quickly in the inner regions of galaxies,suggesting that unseen matter is gravitationally moving this material at faster rates than expected. 
A)  The velocity of stars rises dramatically at large distances from the centers of galaxies,implying large amounts of dark matter cause these stars to move much faster than stars at smaller distances. 
B)  The velocity of stars stays somewhat constant at distances beyond the visible edges of galaxies,implying that more matter than what we observe in stars and gas must be there. 
C)  The velocity of stars is low in the inner regions of galaxies,suggesting that dark matter is impeding their motion. 
D)  The velocity of stars rises quickly in the inner regions of galaxies,suggesting that unseen matter is gravitationally moving this material at faster rates than expected.

Question 15

Once we get outside the dark matter halo of a galaxy,how should the speed of an orbiting body such as a satellite dwarf galaxy depend on its distance from the giant galaxy's center?

Accepted Answer

When you are outside the giant

Question 16

What could you use to measure the mass of the dark matter halo in a spiral galaxy?

Accepted Answer

A)  H $\Pi$ emission from H II regions in the spiral disk 
B)  The velocities of satellite dwarf galaxies surrounding a spiral galaxy 
C)  Absorption lines in the spectra of its globular clusters 
D)  All of the above 
A)  H $\Pi$ emission from H II regions in the spiral disk 
B)  The velocities of satellite dwarf galaxies surrounding a spiral galaxy 
C)  Absorption lines in the spectra of its globular clusters 
D)  All of the above

Question 17

If a Seyfert galaxy's nucleus varies in brightness on the timescale of 10 hours,then approximately what is the size of the emitting region?

Accepted Answer

A)  20 AU 
B)  70 AU 
C)  90 AU 
D)  140 AU 
A)  20 AU 
B)  70 AU 
C)  90 AU 
D)  140 AU

Question 18

What makes up the majority of the mass of an individual spiral galaxy?

Accepted Answer

A)  A central supermassive black hole 
B)  Dark matter 
C)  Massive O- and B-type stars 
D)  Cold molecular gas clouds 
A)  A central supermassive black hole 
B)  Dark matter 
C)  Massive O- and B-type stars 
D)  Cold molecular gas clouds

Question 19

We know that spiral galaxies contain dark matter because the gas in the disk rotates with a velocity that decreases in a way that is proportional to   .

Accepted Answer

A) True 
 B)False

Question 20

The disks of spiral galaxies appear blue because

Accepted Answer

A)  spiral galaxies are moving toward us. 
B)  spiral galaxies contain mostly hot blue stars. 
C)  spiral galaxies are still undergoing star formation. 
D)  spiral galaxies contain more metals that,when ionized,emit blue light. 
A)  spiral galaxies are moving toward us. 
B)  spiral galaxies contain mostly hot blue stars. 
C)  spiral galaxies are still undergoing star formation. 
D)  spiral galaxies contain more metals that,when ionized,emit blue light.

Exam 19: Galaxies

We interpret the fact that we saw more AGNs in the past than we do today to indicate that

How do astronomers know that AGNs are as small as our Solar System?

We know AGN are about the size of our Solar System because of imaging done with the Hubble Space Telescope.

Give three examples of types of active galactic nuclei and give one reason why each is unique.

In spiral galaxies,the size of the central bulge is correlated with the

What is the difference between a Seyfert galaxy and a normal spiral galaxy?

Seyfert galaxies are unique because they have large lobes of radio emission that extend well beyond the visible part of the galaxy.

AGNs appear to be powered by

Describe two ways by which spiral structure may be induced in a spiral galaxy's disk.

If the radio lobes of a radio galaxy extend out to 10 Mpc from the center of the galaxy and the particles in them are traveling at approximately 0.99 c,then how long must the black hole at the center have been ejecting this material into space? Note that and .

If the average quasar has a luminosity of and an absolute magnitude of -40 and you discover one that has an apparent magnitude of +9,then what is its distance?

More luminous giant galaxies tend to have __________ supermassive black holes at their centers.

In some radio galaxies,we only see one side of the jet because

Why do rotation curves of galaxies imply that dark matter exists?

Once we get outside the dark matter halo of a galaxy,how should the speed of an orbiting body such as a satellite dwarf galaxy depend on its distance from the giant galaxy's center?

What could you use to measure the mass of the dark matter halo in a spiral galaxy?

If a Seyfert galaxy's nucleus varies in brightness on the timescale of 10 hours,then approximately what is the size of the emitting region?

What makes up the majority of the mass of an individual spiral galaxy?

We know that spiral galaxies contain dark matter because the gas in the disk rotates with a velocity that decreases in a way that is proportional to .

The disks of spiral galaxies appear blue because

Why Learn Astronomy

Patterns in the Skymotions of Earth

Gravity and Orbitsa Celestial Ballet

Light

The Tools of the Astronomer

The Birth and Evolution of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquidthe Giant Planets

Gravity Is More Than Keplers Laws

Planetary Adornmentsmoons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

A Run-Of-The-Mill G-Type Starour Sun

Star Formation and the Interstellar Medium

Stars in the Slow Lanelow-Mass Stellar Evolution

Live Fast,die Younghigh-Mass Stellar Evolution

Our Expanding Universe

The Milky Waya Normal Spiral Galaxy

Modern Cosmology

The Origin of Structure

Life

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