Question 1

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 2

By what are the real shapes of galaxies defined?

Accepted Answer

They are defined by the velocities of stars in them.

Question 3

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 A

Question 4

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 nebulae 
A)  Novae 
B)  Type I supernovae 
C)  Type II supernovae 
D)  Planetary nebulae

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

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. 
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.

Question 7

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

Accepted Answer

A) True 
 B)False

Question 8

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 9

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. 
A)  They are very far away. 
B)  They are moving away from us. 
C)  They have rapid internal motions. 
D)  They are very dense.

Question 10

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

Accepted Answer

The most likely source of the

Question 11

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

Accepted Answer

A) True 
 B)False

Question 12

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)  quasars 
A)  spiral galaxies 
B)  elliptical galaxies 
C)  elliptical galaxies and spiral bulges 
D)  quasars

Question 13

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

Accepted Answer

A) True 
 B)False

Question 14

What is the connection between active galaxies and galactic mergers?

Accepted Answer

Astronomers believe that galactic merger

Question 15

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. 
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.

Question 16

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

Accepted Answer

A) True 
 B)False

Question 17

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. 
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.

Question 18

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. 
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.

Question 19

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

Accepted Answer

Spirals contain lots of cold gas in thei

Question 20

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

Accepted Answer

A)  X-ray 
B)  Cosmic ray 
C)  Radio 
D)  Infrared 
A)  X-ray 
B)  Cosmic ray 
C)  Radio 
D)  Infrared

Exam 19: Galaxies

Why is our own galaxy not an active galaxy today?

By what are the real shapes of galaxies defined?

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

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

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

Elliptical galaxies appear red because

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

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

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

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

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

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

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

What is the connection between active galaxies and galactic mergers?

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

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

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

Spiral structure

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

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

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

Filters