Question 1

In the search for MACHOs,which meter in the figure below would register the brightest value?

Accepted Answer

A)  Brightness meter A 
B)  Brightness meter B 
C)  Brightness meter C 
D)  All of them would register the same brightness 
A)  Brightness meter A 
B)  Brightness meter B 
C)  Brightness meter C 
D)  All of them would register the same brightness

Question 2

How did Hubble use his tuning fork diagram (figure below)to classify galaxies? Is there any significance to this organization?

Accepted Answer

Elliptical and spiral galaxies are organ

Question 3

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

Accepted Answer

AGNs have been observed to vary dramatic

Question 4

How do we know that AGN have sizes on the order of our Solar System?

Accepted Answer

A)  Quasars and Seyfert galaxies are stellar-like sources. 
B)  Their brightness varies by factors of a few. 
C)  The emission lines in their spectra show gas rotating at speeds of thousands of km/s. 
D)  Their brightness varies on timescales of hours to a day. 
A)  Quasars and Seyfert galaxies are stellar-like sources. 
B)  Their brightness varies by factors of a few. 
C)  The emission lines in their spectra show gas rotating at speeds of thousands of km/s. 
D)  Their brightness varies on timescales of hours to a day.

Question 5

Star formation in spiral galaxies happens only in the spiral arms.

Accepted Answer

A) True 
 B)False

Question 6

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 7

Roughly what percentage of the total mass of a galaxy is made up of luminous,or normal,matter?

Accepted Answer

A)  5 percent 
B)  25 percent 
C)  50 percent 
D)  90 percent 
A)  5 percent 
B)  25 percent 
C)  50 percent 
D)  90 percent

Question 8

How did astronomers determine that elliptical galaxies are composed mostly of dark matter?

Accepted Answer

A)  They measured X-ray emission from hot gas gravitationally bound to the galaxies. 
B)  They measured the rotation rates of gas as a function of distance from the centers of the galaxies. 
C)  They measured the amount of gravitational pull elliptical galaxies have on companion galaxies. 
D)  They assumed that the proportion of dark matter was roughly the same as in spiral galaxies. 
A)  They measured X-ray emission from hot gas gravitationally bound to the galaxies. 
B)  They measured the rotation rates of gas as a function of distance from the centers of the galaxies. 
C)  They measured the amount of gravitational pull elliptical galaxies have on companion galaxies. 
D)  They assumed that the proportion of dark matter was roughly the same as in spiral galaxies.

Question 9

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 1 Mpc = 3.1 × 1022 m and 1 year = 3 × 107 s.

Accepted Answer

Because v = d/t,the length of

Question 10

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

Accepted Answer

Possibilities are: (1)gravitational inte

Question 11

Dark matter is distributed inside galaxies in exactly the same way as luminous matter,although the total mass of dark matter is much larger than that of luminous matter.

Accepted Answer

A) True 
 B)False

Question 12

The figure below shows the unified model of AGNs along with three observers.Which observer would have the least ability to see detail in the object?

Accepted Answer

A)  Observer A 
B)  Observer B 
C)  Observer C 
D)  All observers can equally see detail in the object. 
A)  Observer A 
B)  Observer B 
C)  Observer C 
D)  All observers can equally see detail in the object.

Question 13

What is the connection between active galaxies and galactic mergers?

Accepted Answer

Astronomers believe that galactic merger

Question 14

How do the current star formation rates of spiral and elliptical galaxies compare?

Accepted Answer

Spirals contain lots of cold gas in thei

Question 15

If the rotational speed of the gas in the disk of a spiral galaxy is 200 km/s at a distance of 80,000 light-years from its center,then what is the mass enclosed within this radius?

Accepted Answer

A)  7.5 billion M$\odot$  
B)  18 billion M$\odot$  
C)  70 billion M$\odot$  
D)  230 billion M$\odot$  
A)  7.5 billion M$\odot$  
B)  18 billion M$\odot$  
C)  70 billion M$\odot$  
D)  230 billion M$\odot$

Question 16

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

Question 17

Galaxies that are classified as quasars were much more numerous in the past.

Accepted Answer

A) True 
 B)False

Question 18

Assume that when a supermassive black hole accretes gas,approximately 50 percent of its mass is converted directly into energy,which is radiated away.If a quasar has a luminosity of 1014 L$\odot$ then what must its mass accretion rate be?

Accepted Answer

A)  1 M $\odot$  per year 
B)  10 M$\odot$  per year 
C)  1 M$\odot$  per century 
D)  10 M$\odot$ per million years 
A)  1 M $\odot$  per year 
B)  10 M$\odot$  per year 
C)  1 M$\odot$  per century 
D)  10 M$\odot$ per million years

Question 19

Which of the following are NOT predominantly found in the spiral arms of galaxies?

Accepted Answer

A)  Molecular clouds 
B)  H II regions 
C)  K- and M-type stars 
D)  Type II supernovae 
A)  Molecular clouds 
B)  H II regions 
C)  K- and M-type stars 
D)  Type II supernovae

Question 20

The image below is of a spiral galaxy.   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

In the search for MACHOs,which meter in the figure below would register the brightest value?

How did Hubble use his tuning fork diagram (figure below)to classify galaxies? Is there any significance to this organization?

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

How do we know that AGN have sizes on the order of our Solar System?

Star formation in spiral galaxies happens only in the spiral arms.

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

Roughly what percentage of the total mass of a galaxy is made up of luminous,or normal,matter?

How did astronomers determine that elliptical galaxies are composed mostly of dark matter?

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

Dark matter is distributed inside galaxies in exactly the same way as luminous matter,although the total mass of dark matter is much larger than that of luminous matter.

The figure below shows the unified model of AGNs along with three observers.Which observer would have the least ability to see detail in the object?

What is the connection between active galaxies and galactic mergers?

How do the current star formation rates of spiral and elliptical galaxies compare?

If the rotational speed of the gas in the disk of a spiral galaxy is 200 km/s at a distance of 80,000 light-years from its center,then what is the mass enclosed within this radius?

The disks of spiral galaxies appear blue because:

Galaxies that are classified as quasars were much more numerous in the past.

Assume that when a supermassive black hole accretes gas,approximately 50 percent of its mass is converted directly into energy,which is radiated away.If a quasar has a luminosity of 10¹⁴ L_$\odot$then what must its mass accretion rate be?

Which of the following are NOT predominantly found in the spiral arms of galaxies?

The image below is of a spiral galaxy. In spiral galaxies,the size of the central bulge is correlated with the:

Our Place in the Universe

Patterns in the Skymotions of Earth

Laws of Motion

Light and Telescopes

The Formation of Stars and Planets

Terrestrial Worlds in the Inner Solar System

Atmospheres of Venus, Earth, and Mars

The Giant Planets

Small Bodies of the Solar System

Measuring the Stars

Our Star: The Sun

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

The Expansion of Space

Our Galaxy: The Milky Way

Modern Cosmology and the Origin of Structure

Life in the Universe

Filters

Exam 15: The Realm of the Galaxies

In the search for MACHOs,which meter in the figure below would register the brightest value?

How did Hubble use his tuning fork diagram (figure below)to classify galaxies? Is there any significance to this organization?

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

How do we know that AGN have sizes on the order of our Solar System?

Star formation in spiral galaxies happens only in the spiral arms.

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

Roughly what percentage of the total mass of a galaxy is made up of luminous,or normal,matter?

How did astronomers determine that elliptical galaxies are composed mostly of dark matter?

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

Dark matter is distributed inside galaxies in exactly the same way as luminous matter,although the total mass of dark matter is much larger than that of luminous matter.

The figure below shows the unified model of AGNs along with three observers.Which observer would have the least ability to see detail in the object?

What is the connection between active galaxies and galactic mergers?

How do the current star formation rates of spiral and elliptical galaxies compare?

If the rotational speed of the gas in the disk of a spiral galaxy is 200 km/s at a distance of 80,000 light-years from its center,then what is the mass enclosed within this radius?

The disks of spiral galaxies appear blue because:

Galaxies that are classified as quasars were much more numerous in the past.

Assume that when a supermassive black hole accretes gas,approximately 50 percent of its mass is converted directly into energy,which is radiated away.If a quasar has a luminosity of 1014 L ⊙\odot⊙ then what must its mass accretion rate be?

Which of the following are NOT predominantly found in the spiral arms of galaxies?

The image below is of a spiral galaxy. In spiral galaxies,the size of the central bulge is correlated with the:

Our Place in the Universe

Patterns in the Skymotions of Earth

Laws of Motion

Light and Telescopes

The Formation of Stars and Planets

Terrestrial Worlds in the Inner Solar System

Atmospheres of Venus, Earth, and Mars

The Giant Planets

Small Bodies of the Solar System

Measuring the Stars

Our Star: The Sun

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

The Expansion of Space

Our Galaxy: The Milky Way

Modern Cosmology and the Origin of Structure

Life in the Universe

Filters

Assume that when a supermassive black hole accretes gas,approximately 50 percent of its mass is converted directly into energy,which is radiated away.If a quasar has a luminosity of 10¹⁴ L_$\odot$then what must its mass accretion rate be?