Question 1

What evidence supports the idea that a collision between two spiral galaxies might lead to the formation of a single elliptical galaxy?

Accepted Answer

A) the fact that elliptical galaxies dominate the galaxy populations at the cores of dense clusters of galaxies 
B) observations of giant elliptical galaxies at the center of dense clusters that may have grown by consuming other galaxies 
C) observations of some elliptical galaxies with stars and gas clouds in their cores that orbit differently from the other stars in the galaxy 
D) observations of some elliptical galaxies surrounded by shells of stars that probably formed from stars stripped out of smaller galaxies 
E) all of the above 
A) the fact that elliptical galaxies dominate the galaxy populations at the cores of dense clusters of galaxies 
B) observations of giant elliptical galaxies at the center of dense clusters that may have grown by consuming other galaxies 
C) observations of some elliptical galaxies with stars and gas clouds in their cores that orbit differently from the other stars in the galaxy 
D) observations of some elliptical galaxies surrounded by shells of stars that probably formed from stars stripped out of smaller galaxies 
E) all of the above

Question 2

A quasar's spectrum is hugely redshifted. What does this large redshift tells us about the quasar?

Accepted Answer

A) the distance to the quasar 
B) the size of the quasar's central, supermassive black hole 
C) the type of host galaxy in which the quasar resides 
D) the composition of the quasar 
A) the distance to the quasar 
B) the size of the quasar's central, supermassive black hole 
C) the type of host galaxy in which the quasar resides 
D) the composition of the quasar

Question 3

What is the most accurate way to determine the distance to a very distant galaxy?

Accepted Answer

A) main- sequence fitting 
B) Hubble's law 
C) Cepheid variables 
D) Stellar parallax 
E) white dwarf supernova 
A) main- sequence fitting 
B) Hubble's law 
C) Cepheid variables 
D) Stellar parallax 
E) white dwarf supernova

Question 4

How does a starburst end? What might happen to the galaxy afterwards?

Accepted Answer

A starburst might end by simply using up

Question 5

Which of the following is not a piece of evidence supporting the conclusion that active galactic nuclei are powered by accretion disks around massive black holes?

Accepted Answer

A) Radio observations sometimes show long jets of material that can extend millions of light- years out from the galactic center. 
B) Spectral lines from the galactic center indicate that clouds of gas are orbiting a central object at very high speed. 
C) Infrared observations show that many stars are forming near the centers of active galaxies. 
D) The total amount of radiation coming from the galactic center can, in some cases, exceed 100 times the total luminosity of the Milky Way Galaxy. 
E) Observed radiation from the galactic center can vary significantly in brightness in times as short as a few days. 
A) Radio observations sometimes show long jets of material that can extend millions of light- years out from the galactic center. 
B) Spectral lines from the galactic center indicate that clouds of gas are orbiting a central object at very high speed. 
C) Infrared observations show that many stars are forming near the centers of active galaxies. 
D) The total amount of radiation coming from the galactic center can, in some cases, exceed 100 times the total luminosity of the Milky Way Galaxy. 
E) Observed radiation from the galactic center can vary significantly in brightness in times as short as a few days.

Question 6

What is a Cepheid variable?

Accepted Answer

A) a bright source of variable X- ray emission, thought to harbor a supermassive black hole 
B) a main- sequence star of spectral type B5 
C) a type of galaxy that varies in its light output 
D) a type of very luminous star that makes an excellent standard candle 
A) a bright source of variable X- ray emission, thought to harbor a supermassive black hole 
B) a main- sequence star of spectral type B5 
C) a type of galaxy that varies in its light output 
D) a type of very luminous star that makes an excellent standard candle

Question 7

Why are white dwarf supernovae more useful than massive star supernovae for measuring cosmic distances?

Accepted Answer

A) White dwarf supernovae are much more common than massive star supernovae. 
B) We can see only white dwarf supernovae in distant galaxies, not massive star supernovae. 
C) White dwarf supernovae follow a period- luminosity relation, while massive supernovae do not. 
D) White dwarf supernovae all have roughly the same true peak luminosity, while massive supernovae come in a wide range of peak luminosities. 
A) White dwarf supernovae are much more common than massive star supernovae. 
B) We can see only white dwarf supernovae in distant galaxies, not massive star supernovae. 
C) White dwarf supernovae follow a period- luminosity relation, while massive supernovae do not. 
D) White dwarf supernovae all have roughly the same true peak luminosity, while massive supernovae come in a wide range of peak luminosities.

Question 8

We can study how galaxies evolve because .

Accepted Answer

A) we can watch as they interact in real time 
B) we are really smart astronomers 
C) the farther away we look, the further back in time we see 
D) galaxies are transparent to visible light 
A) we can watch as they interact in real time 
B) we are really smart astronomers 
C) the farther away we look, the further back in time we see 
D) galaxies are transparent to visible light

Question 9

Which of the following is evidence for supermassive black holes in active galaxies?

Accepted Answer

A) rapid changes in the luminosity of the galaxy nucleus 
B) quasars emitting approximately equal power at all wavelengths from infrared to gamma rays 
C) the very high speeds of gas orbiting around the galactic nucleus 
D) the discovery of powerful jets coming from a compact core 
E) all of the above 
A) rapid changes in the luminosity of the galaxy nucleus 
B) quasars emitting approximately equal power at all wavelengths from infrared to gamma rays 
C) the very high speeds of gas orbiting around the galactic nucleus 
D) the discovery of powerful jets coming from a compact core 
E) all of the above

Question 10

Suppose that we look at a photograph of many galaxies. Assuming that all galaxies formed at about the same time, which galaxy in the picture is the youngest?

Accepted Answer

A) the one that is bluest in color 
B) the one that is reddest in color 
C) the one that is closest to us 
D) the one that is farthest away 
E) the one that appears smallest in size 
A) the one that is bluest in color 
B) the one that is reddest in color 
C) the one that is closest to us 
D) the one that is farthest away 
E) the one that appears smallest in size

Question 11

This figure shows Hubble's law. If a galaxy is observed to be moving away from us at 30,000 km/s, how far away is it?

Accepted Answer

A) about 30,000 light- years 
B) about 900 million light- years 
C) about 5000 million light- years 
D) about 1400 million light- years 
A) about 30,000 light- years 
B) about 900 million light- years 
C) about 5000 million light- years 
D) about 1400 million light- years

Question 12

Use the graph above showing data for the brightest galaxies in clusters of galaxies to answer the following question. If new studies show that the exceptions are a class of galaxies with extraordinarily bright centers, which conclusion is not justified based on the plot and the findings of these new studies?

Accepted Answer

A) Bright nuclei were more common long ago, since the light from more distant galaxies has been traveling much longer. 
B) Bright nuclei are caused by supermassive black holes surrounded by hot gas. 
C) Bright nuclei are more common in cluster galaxies that are farther away. 
D) Galaxies appear redder the farther away they are. 
A) Bright nuclei were more common long ago, since the light from more distant galaxies has been traveling much longer. 
B) Bright nuclei are caused by supermassive black holes surrounded by hot gas. 
C) Bright nuclei are more common in cluster galaxies that are farther away. 
D) Galaxies appear redder the farther away they are.

Question 13

Suppose we observe a Cepheid variable in a distant galaxy. The Cepheid brightens and dims with a regular period of about 10 days. What can we learn from this observation?

Accepted Answer

A) It will allow us to determine the mass of the galaxy. 
B) Under the rules of the International Astronomical Union, we will be entitled to naming rights for the galaxy. 
C) It will allow us to calculate the rotation rate of the galaxy. 
D) We can learn the distance to the galaxy. 
A) It will allow us to determine the mass of the galaxy. 
B) Under the rules of the International Astronomical Union, we will be entitled to naming rights for the galaxy. 
C) It will allow us to calculate the rotation rate of the galaxy. 
D) We can learn the distance to the galaxy.

Question 14

Which of the following phenomena are not thought to be results of collisions or other interactions between galaxies?

Accepted Answer

A) the fact that elliptical galaxies are more common in clusters of galaxies than outside clusters 
B) starbursts 
C) the fact that spiral galaxies have both disk and halo components 
D) the presence of very large, central dominant galaxies in clusters of galaxies 
A) the fact that elliptical galaxies are more common in clusters of galaxies than outside clusters 
B) starbursts 
C) the fact that spiral galaxies have both disk and halo components 
D) the presence of very large, central dominant galaxies in clusters of galaxies

Question 15

The most basic difference between elliptical galaxies and spiral galaxies is that .

Accepted Answer

A) elliptical galaxies are very old and spiral galaxies are very young 
B) elliptical galaxies lack anything resembling the disk of a spiral galaxy 
C) elliptical galaxies lack anything resembling the halo of a spiral galaxy 
D) elliptical galaxies have a spheroidal component (of stars distributed spherically about the galactic center), and spiral galaxies do not 
A) elliptical galaxies are very old and spiral galaxies are very young 
B) elliptical galaxies lack anything resembling the disk of a spiral galaxy 
C) elliptical galaxies lack anything resembling the halo of a spiral galaxy 
D) elliptical galaxies have a spheroidal component (of stars distributed spherically about the galactic center), and spiral galaxies do not

Question 16

How did Edwin Hubble measure the distance to the Andromeda Galaxy?

Accepted Answer

A) He applied the period- luminosity relation to Cepheid variables in Andromeda. 
B) He measured its parallax. 
C) He detected white dwarf supernovae in Andromeda. 
D) He applied main- sequence fitting to star clusters in Andromeda. 
E) He measured its redshift and applied Hubble's Law. 
A) He applied the period- luminosity relation to Cepheid variables in Andromeda. 
B) He measured its parallax. 
C) He detected white dwarf supernovae in Andromeda. 
D) He applied main- sequence fitting to star clusters in Andromeda. 
E) He measured its redshift and applied Hubble's Law.

Question 17

The larger the value of Hubble's constant, the more rapid the expansion of the universe and the smaller (and hence younger)our estimate for the age of the universe.

Accepted Answer

A) True 
 B)False

Question 18

Recall that Hubble's law is written v = H0d, where v is the recession velocity of a galaxy located a distance d away from us, and H0 is Hubble's constant. Suppose H0 = 20 km/s/Mly. How fast would a galaxy 1000 Mly distant be receding from us?

Accepted Answer

A) 20 Mly/s 
B) 20,000 km/s 
C) 0)20 times the speed of light 
D) 50 km/s 
E) 20 km/s 
A) 20 Mly/s 
B) 20,000 km/s 
C) 0)20 times the speed of light 
D) 50 km/s 
E) 20 km/s

Question 19

Where are the X- rays produced that are emitted by quasars and other active galactic nuclei?

Accepted Answer

A) in the hot gas in an accretion disk around a central black hole 
B) in an ionization nebulae of interstellar gas surrounding the accretion disk 
C) in fast- moving jets of electrons that are ejected from the active galactic nucleus 
D) in dust grains in molecular clouds that encircle the active galactic nucleus 
E) all of the above 
A) in the hot gas in an accretion disk around a central black hole 
B) in an ionization nebulae of interstellar gas surrounding the accretion disk 
C) in fast- moving jets of electrons that are ejected from the active galactic nucleus 
D) in dust grains in molecular clouds that encircle the active galactic nucleus 
E) all of the above

Question 20

Using the technique of main- sequence fitting to determine the distance to a star cluster requires that .

Accepted Answer

A) we use ultraviolet and X- ray telescopes 
B) we have telescopes powerful enough to allow us to identify the spectral types of main- sequence stars of many masses in the cluster 
C) the cluster be near enough for us to measure the parallax of its stars 
D) we have a well- calibrated period- luminosity relation for Cepheid variable stars 
A) we use ultraviolet and X- ray telescopes 
B) we have telescopes powerful enough to allow us to identify the spectral types of main- sequence stars of many masses in the cluster 
C) the cluster be near enough for us to measure the parallax of its stars 
D) we have a well- calibrated period- luminosity relation for Cepheid variable stars

What evidence supports the idea that a collision between two spiral galaxies might lead to the formation of a single elliptical galaxy?

A quasar's spectrum is hugely redshifted. What does this large redshift tells us about the quasar?

What is the most accurate way to determine the distance to a very distant galaxy?

How does a starburst end? What might happen to the galaxy afterwards?

Which of the following is not a piece of evidence supporting the conclusion that active galactic nuclei are powered by accretion disks around massive black holes?

What is a Cepheid variable?

Why are white dwarf supernovae more useful than massive star supernovae for measuring cosmic distances?

We can study how galaxies evolve because .

Which of the following is evidence for supermassive black holes in active galaxies?

Suppose that we look at a photograph of many galaxies. Assuming that all galaxies formed at about the same time, which galaxy in the picture is the youngest?

This figure shows Hubble's law. If a galaxy is observed to be moving away from us at 30,000 km/s, how far away is it?

Suppose we observe a Cepheid variable in a distant galaxy. The Cepheid brightens and dims with a regular period of about 10 days. What can we learn from this observation?

Which of the following phenomena are not thought to be results of collisions or other interactions between galaxies?

The most basic difference between elliptical galaxies and spiral galaxies is that .

How did Edwin Hubble measure the distance to the Andromeda Galaxy?

The larger the value of Hubble's constant, the more rapid the expansion of the universe and the smaller (and hence younger)our estimate for the age of the universe.

Recall that Hubble's law is written v = H0d, where v is the recession velocity of a galaxy located a distance d away from us, and H0 is Hubble's constant. Suppose H0 = 20 km/s/Mly. How fast would a galaxy 1000 Mly distant be receding from us?

Where are the X- rays produced that are emitted by quasars and other active galactic nuclei?

Using the technique of main- sequence fitting to determine the distance to a star cluster requires that .

A Modern View of the Universe

Discovering the Universe for Yourself

The Science of Astronomy

Making Sense of the Universe: Understanding Motion, Energy, and Gravity

Light: the Cosmic Messenger

Formation of the Solar System

Earth and the Terrestrial Worlds

Jovian Planet System

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Other Planetary Systems: the New Science of Distant Worlds

Our Star

Surveying the Stars

Star Stuff

The Bizarre Stellar Graveyard

Our Galaxy

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Dark Matter, Dark Energy, and the Fate of the Universe

Life in the Universe

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Exam 16: A Universe of Galaxies

What evidence supports the idea that a collision between two spiral galaxies might lead to the formation of a single elliptical galaxy?

A quasar's spectrum is hugely redshifted. What does this large redshift tells us about the quasar?

What is the most accurate way to determine the distance to a very distant galaxy?

How does a starburst end? What might happen to the galaxy afterwards?

Which of the following is not a piece of evidence supporting the conclusion that active galactic nuclei are powered by accretion disks around massive black holes?

What is a Cepheid variable?

Why are white dwarf supernovae more useful than massive star supernovae for measuring cosmic distances?

We can study how galaxies evolve because .

Which of the following is evidence for supermassive black holes in active galaxies?

Suppose that we look at a photograph of many galaxies. Assuming that all galaxies formed at about the same time, which galaxy in the picture is the youngest?

This figure shows Hubble's law. If a galaxy is observed to be moving away from us at 30,000 km/s, how far away is it?

Suppose we observe a Cepheid variable in a distant galaxy. The Cepheid brightens and dims with a regular period of about 10 days. What can we learn from this observation?

Which of the following phenomena are not thought to be results of collisions or other interactions between galaxies?

The most basic difference between elliptical galaxies and spiral galaxies is that .

How did Edwin Hubble measure the distance to the Andromeda Galaxy?

The larger the value of Hubble's constant, the more rapid the expansion of the universe and the smaller (and hence younger)our estimate for the age of the universe.

Recall that Hubble's law is written v = H0d, where v is the recession velocity of a galaxy located a distance d away from us, and H0 is Hubble's constant. Suppose H0 = 20 km/s/Mly. How fast would a galaxy 1000 Mly distant be receding from us?

Where are the X- rays produced that are emitted by quasars and other active galactic nuclei?

Using the technique of main- sequence fitting to determine the distance to a star cluster requires that .

A Modern View of the Universe

Discovering the Universe for Yourself

The Science of Astronomy

Making Sense of the Universe: Understanding Motion, Energy, and Gravity

Light: the Cosmic Messenger

Formation of the Solar System

Earth and the Terrestrial Worlds

Jovian Planet System

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Other Planetary Systems: the New Science of Distant Worlds

Our Star

Surveying the Stars

Star Stuff

The Bizarre Stellar Graveyard

Our Galaxy

The Birth of the Universe

Dark Matter, Dark Energy, and the Fate of the Universe

Life in the Universe

Filters