Question 1

AGNs appear to be powered by:

Accepted Answer

A) extremely dense star clusters 
B) supermassive black holes 
C) ultradense molecular clouds 
D) decaying dark matter 
E) supernova explosion 
A) extremely dense star clusters 
B) supermassive black holes 
C) ultradense molecular clouds 
D) decaying dark matter 
E) supernova explosion

Question 2

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 are sometimes very thin in appearance whereas elliptical galaxies are always round or elliptical. 
C) Spiral galaxy disks contain lots of cold gas and dust whereas elliptical galaxies do not. 
D) Spiral galaxies tend to have bluish areas whereas elliptical galaxies tend to be all reddish. 
E) Spiral galaxies have dark matter halos whereas elliptical galaxies do not. 
A) Spiral galaxies still have ongoing star formation whereas elliptical galaxies do not. 
B) Spiral galaxies are sometimes very thin in appearance whereas elliptical galaxies are always round or elliptical. 
C) Spiral galaxy disks contain lots of cold gas and dust whereas elliptical galaxies do not. 
D) Spiral galaxies tend to have bluish areas whereas elliptical galaxies tend to be all reddish. 
E) Spiral galaxies have dark matter halos whereas elliptical galaxies do not.

Question 3

Stars in elliptical galaxies have velocities that:

Accepted Answer

A) change constantly 
B) are very large in size 
C) are equal in all directions 
D) are constant in time 
E) are orientated in random in directions 
A) change constantly 
B) are very large in size 
C) are equal in all directions 
D) are constant in time 
E) are orientated in random in directions

Question 4

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 galaxy's

Question 5

A galaxy can contain a supermassive black hole that remains invisible because no matter is falling onto the black hole.

Accepted Answer

A) True 
 B)False

Question 6

The density of ordinary luminous matter can exceed the density of dark matter in which parts of galaxies?

Accepted Answer

A) everywhere inside galaxies 
B) only in the outer regions of galaxies 
C) only in star clusters 
D) near the centers of galaxies 
E) only around an AGN 
A) everywhere inside galaxies 
B) only in the outer regions of galaxies 
C) only in star clusters 
D) near the centers of galaxies 
E) only around an AGN

Question 7

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

Accepted Answer

Spirals contain lots of cold gas in thei

Question 8

How do we know that AGNs 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 ranging from hours to a day. 
E) We can measure their angular size,which gives us the physical size when we know the distance. 
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 ranging from hours to a day. 
E) We can measure their angular size,which gives us the physical size when we know the distance.

Question 9

What do the formation of the Solar System and the existence of AGNs have in common?

Accepted Answer

A) They both demonstrate the importance of how luminosity varies with time. 
B) They both demonstrate the high efficiency of nuclear fusion. 
C) They both demonstrate the importance of accretion disks. 
D) They both demonstrate the importance of living in the center of a galaxy. 
E) They both demonstrate the existence of dark matter. 
A) They both demonstrate the importance of how luminosity varies with time. 
B) They both demonstrate the high efficiency of nuclear fusion. 
C) They both demonstrate the importance of accretion disks. 
D) They both demonstrate the importance of living in the center of a galaxy. 
E) They both demonstrate the existence of dark matter.

Question 10

Although elliptical and irregular galaxies have been observed in both dwarf and giant varieties,we find only giant spiral galaxies.

Accepted Answer

A) True 
 B)False

Question 11

What type of galaxy is this?

Accepted Answer

A) a giant elliptical 
B) an ordinary spiral galaxy 
C) an irregular galaxy 
D) a barred spiral 
E) a dwarf elliptical 
A) a giant elliptical 
B) an ordinary spiral galaxy 
C) an irregular galaxy 
D) a barred spiral 
E) a dwarf elliptical

Question 12

How do we know that the stellar disks in spiral galaxies are flat? How do we know that elliptical galaxies are not flat?

Accepted Answer

Individual galaxies are oriented at a va

Question 13

What is the approximate percentage of nearby galaxies that contain AGNs?

Accepted Answer

A) 3 percent 
B) 15 percent 
C) 20 percent 
D) 50 percent 
E) 80 percent 
A) 3 percent 
B) 15 percent 
C) 20 percent 
D) 50 percent 
E) 80 percent

AGNs appear to be powered by:

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

Stars in elliptical galaxies have velocities that:

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?

A galaxy can contain a supermassive black hole that remains invisible because no matter is falling onto the black hole.

The density of ordinary luminous matter can exceed the density of dark matter in which parts of galaxies?

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

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

What do the formation of the Solar System and the existence of AGNs have in common?

Although elliptical and irregular galaxies have been observed in both dwarf and giant varieties,we find only giant spiral galaxies.

What type of galaxy is this?

How do we know that the stellar disks in spiral galaxies are flat? How do we know that elliptical galaxies are not flat?

What is the approximate percentage of nearby galaxies that contain AGNs?

Why Learn Astronomy

Patterns in the Skymotions of Earth

Motion of Astronomical Bodies

Gravity and Orbits

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 Liquid the Giant Planets

Planetary Adornments Moons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

Star Formation and the Interstellar Medium

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

The Expanding Universe

The Milky Waya Normal Spiral Galaxy

Modern Cosmology

Large-Scale Structure in the Universe

Life

Filters

Exam 20: Galaxies

AGNs appear to be powered by:

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

Stars in elliptical galaxies have velocities that:

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?

A galaxy can contain a supermassive black hole that remains invisible because no matter is falling onto the black hole.

The density of ordinary luminous matter can exceed the density of dark matter in which parts of galaxies?

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

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

What do the formation of the Solar System and the existence of AGNs have in common?

Although elliptical and irregular galaxies have been observed in both dwarf and giant varieties,we find only giant spiral galaxies.

What type of galaxy is this?

How do we know that the stellar disks in spiral galaxies are flat? How do we know that elliptical galaxies are not flat?

What is the approximate percentage of nearby galaxies that contain AGNs?

Why Learn Astronomy

Patterns in the Skymotions of Earth

Motion of Astronomical Bodies

Gravity and Orbits

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 Liquid the Giant Planets

Planetary Adornments Moons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

Star Formation and the Interstellar Medium

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

The Expanding Universe

The Milky Waya Normal Spiral Galaxy

Modern Cosmology

Large-Scale Structure in the Universe

Life

Filters