Question 1

What is the connection between active galaxies and galactic mergers?

Accepted Answer

Astronomers believe that galactic merger...

Question 2

Quasars were first discovered in which region of the electromagnetic spectrum?

Accepted Answer

A)   X-ray
B)   Cosmic ray
C)   Radio
D)   InfraredE) B) and D)
F) None of the above

Question 3

What happens to active galaxies when their AGNs run out of fuel?

Accepted Answer

A)   The black holes powering them collapse even further.
B)   They simply become normal galaxies.
C)   They slowly dissipate into clouds of gas and dust.
D)   They eventually pull in material from farther out,starting the AGN process all over again.E) A) and D)
F) C) and D)

Question 4

The 3-dimensional shape of __________ is set by the average velocities of the stars along each of the three axes.

Accepted Answer

A)   spiral galaxies
B)   elliptical galaxies
C)   elliptical galaxies and spiral bulges
D)   quasarsE) All of the above
F) A) and B)

Question 5

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

Accepted Answer

Elliptical and spiral galaxies are organ...

Question 6

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 percentE) None of the above
F) A) and B) A

Question 7

Spiral structure

Accepted Answer

A)   rotates at the same speed as the gas in the disk.
B)   rotates at a speed that is different than the gas in the disk.
C)   stays constant in time as the gas in disk rotates through it.
D)   None of the above is true.E) A) and C)
F) B) and C)

Question 8

Elliptical galaxies appear red because

Accepted Answer

A)   they are moving away from us.
B)   they contain mostly ionized hydrogen gas.
C)   they contain mostly old stars.
D)   they contain lots of dust.E) A) and B)
F) B) and C)

Question 9

Which of the following would NOT be found in an elliptical galaxy?

Accepted Answer

A)   Novae
B)   Type I supernovae
C)   Type II supernovae
D)   Planetary nebulaeE) All of the above
F) B) and C)

Question 10

Astronomers believe that all giant galaxies probably contain supermassive black holes.

Accepted Answer

A) True 
 B)False

Question 11

Dark matter consists of material that emits radiation at wavelengths other than visible light.

Accepted Answer

A) True 
 B)False

Question 12

What is the most likely candidate for making up the dark matter in galaxies?

Accepted Answer

The most likely source of the ...

Question 13

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

Accepted Answer

A) True 
 B)False

Question 14

By what are the real shapes of galaxies defined?

Accepted Answer

They are defined by the velocities of stars in them.

Question 15

What do the broad emission lines in quasar spectra tell astronomers about these objects?

Accepted Answer

A)   They are very far away.
B)   They are moving away from us.
C)   They have rapid internal motions.
D)   They are very dense.E) A) and D)
F) None of the above

Question 16

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

Accepted Answer

Spirals contain lots of cold gas in thei...

Question 17

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.E) All of the above
F) B) and D)

Question 18

Which of the following is NOT a difference between spiral and elliptical galaxies?

Accepted Answer

A)   Spiral galaxies still have ongoing star formation whereas elliptical galaxies do not.
B)   Spiral galaxies have dark matter halos whereas elliptical galaxies do not.
C)   Spiral galaxy disks contain lots of cold gas and dust whereas elliptical galaxies do not.
D)   Spiral galaxies tend to be bluish whereas elliptical galaxies tend to be reddish.E) A) and D)
F) All of the above

Question 19

Why is our own galaxy not an active galaxy today?

Accepted Answer

Because there currently is no infall of matter onto the central supermassive black hole.

Question 20

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

Accepted Answer

A) True 
 B)False

Exam 19: Galaxies

What is the connection between active galaxies and galactic mergers?

Correct AnswerverifiedAstronomers believe that galactic merger...View AnswerShow Answer

Quasars were first discovered in which region of the electromagnetic spectrum?

Correct AnswerverifiedShow Answer

What happens to active galaxies when their AGNs run out of fuel?

Correct AnswerverifiedShow Answer

The 3-dimensional shape of __________ is set by the average velocities of the stars along each of the three axes.

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedElliptical and spiral galaxies are organ...View AnswerShow Answer

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

Correct AnswerverifiedA

Spiral structure

Correct AnswerverifiedShow Answer

Elliptical galaxies appear red because

Correct AnswerverifiedShow Answer

Which of the following would NOT be found in an elliptical galaxy?

Correct AnswerverifiedShow Answer

Astronomers believe that all giant galaxies probably contain supermassive black holes.

Correct AnswerverifiedShow Answer

Dark matter consists of material that emits radiation at wavelengths other than visible light.

Correct AnswerverifiedShow Answer

What is the most likely candidate for making up the dark matter in galaxies?

Correct AnswerverifiedThe most likely source of the ...View AnswerShow Answer

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

Correct AnswerverifiedShow Answer

By what are the real shapes of galaxies defined?

Correct AnswerverifiedThey are defined by the velocities of stars in them.

What do the broad emission lines in quasar spectra tell astronomers about these objects?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedSpirals contain lots of cold gas in thei...View AnswerShow Answer

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

Correct AnswerverifiedShow Answer

Which of the following is NOT a difference between spiral and elliptical galaxies?

Correct AnswerverifiedShow Answer

Why is our own galaxy not an active galaxy today?

Correct AnswerverifiedBecause there currently is no infall of matter onto the central supermassive black hole.

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

Correct AnswerverifiedShow Answer

Correct Answer
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Astronomers believe that galactic merger...
View Answer

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Correct Answer
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Correct Answer
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Elliptical and spiral galaxies are organ...
View Answer

Correct Answer
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A

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The most likely source of the ...
View Answer

Correct Answer
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They are defined by the velocities of stars in them.

Correct Answer
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Spirals contain lots of cold gas in thei...
View Answer

Correct Answer
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Correct Answer
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Correct Answer
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Because there currently is no infall of matter onto the central supermassive black hole.

Correct Answer
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