Question 1

Most stars on the main sequence fuse hydrogen into helium in their cores, but some do not.

Accepted Answer

A) True 
 B)False

Question 2

Two stars have the same luminosity. Star X is spectral type F, while Star Y is spectral type K. Star X must be larger in radius than Star Y.

Accepted Answer

A) True 
 B)False

Question 3

A 10 solar mass star is about ten times more luminous than a 1 solar mass star.

Accepted Answer

A) True 
 B)False

Question 4

Which of the following statements comparing open and globular star clusters is not true?

Accepted Answer

A)  Open and globular clusters each typically contain a few hundred stars. 
B)  Open clusters are found only in the disk of the galaxy while globular clusters may be found both in the disk and the halo of the galaxy. 
C)  Stars in open clusters are relatively young while stars in globular clusters are very old. 
D)  For both open and globular clusters, we can assume that all the stars in a particular cluster are about the same age. 
A)  Open and globular clusters each typically contain a few hundred stars. 
B)  Open clusters are found only in the disk of the galaxy while globular clusters may be found both in the disk and the halo of the galaxy. 
C)  Stars in open clusters are relatively young while stars in globular clusters are very old. 
D)  For both open and globular clusters, we can assume that all the stars in a particular cluster are about the same age.

Question 5

If the distance between us and a star is doubled, with everything else remaining the same, its luminosity

Accepted Answer

A)  is decreased by a factor of four, and its apparent brightness is decreased by a factor of four. 
B)  is decreased by a factor of two, and its apparent brightness is decreased by a factor of two. 
C)  remains the same, but its apparent brightness is decreased by a factor of two. 
D)  remains the same, but its apparent brightness is decreased by a factor of four. 
E)  is decreased by a factor of four, but its apparent brightness remains the same. 
A)  is decreased by a factor of four, and its apparent brightness is decreased by a factor of four. 
B)  is decreased by a factor of two, and its apparent brightness is decreased by a factor of two. 
C)  remains the same, but its apparent brightness is decreased by a factor of two. 
D)  remains the same, but its apparent brightness is decreased by a factor of four. 
E)  is decreased by a factor of four, but its apparent brightness remains the same.

Question 6

Star A is identical to Star B, except that Star A is twice as far from us as Star B. Therefore:

Accepted Answer

A)  Both stars have the same luminosity, but the apparent brightness of Star B is four times that of Star A. 
B)  Both stars have the same luminosity, but the apparent brightness of Star B is twice that of Star A. 
C)  Both stars have the same apparent brightness, but the luminosity of Star B is four times that of Star A. 
D)  Both stars have the same luminosity, but the apparent brightness of Star A is four times that of Star B. 
A)  Both stars have the same luminosity, but the apparent brightness of Star B is four times that of Star A. 
B)  Both stars have the same luminosity, but the apparent brightness of Star B is twice that of Star A. 
C)  Both stars have the same apparent brightness, but the luminosity of Star B is four times that of Star A. 
D)  Both stars have the same luminosity, but the apparent brightness of Star A is four times that of Star B.

Question 7

On the main sequence, stars obtain their energy

Accepted Answer

A)  from chemical reactions. 
B)  from gravitational contraction. 
C)  by converting hydrogen to helium. 
D)  by converting helium to carbon, nitrogen, and oxygen. 
E)  from nuclear fission. 
A)  from chemical reactions. 
B)  from gravitational contraction. 
C)  by converting hydrogen to helium. 
D)  by converting helium to carbon, nitrogen, and oxygen. 
E)  from nuclear fission.

Question 8

Which stellar spectral type has strong molecular absorption lines in its optical spectrum?

Accepted Answer

A)  O 
B)  B 
C)  G 
D)  K 
E)  M 
A)  O 
B)  B 
C)  G 
D)  K 
E)  M

Question 9

A star of spectral type G lives approximately how long on the main sequence?

Accepted Answer

A)  1,000 years 
B)  10,000 years 
C)  10 million years 
D)  1 billion years 
E)  10 billion years 
A)  1,000 years 
B)  10,000 years 
C)  10 million years 
D)  1 billion years 
E)  10 billion years

Question 10

Which star is the hottest star?

Accepted Answer

A)  G 
B)  A 
C)  O 
D)  M 
E)  Can't tell from information provided. 
A)  G 
B)  A 
C)  O 
D)  M 
E)  Can't tell from information provided.

Question 11

Ten parsecs is about ________.

Accepted Answer

A)  150 million kilometers 
B)  32.6 light-years 
C)  10,000 seconds 
D)  10 parallax seconds of angle 
A)  150 million kilometers 
B)  32.6 light-years 
C)  10,000 seconds 
D)  10 parallax seconds of angle

Question 12

You see two main-sequence stars with the same spectral type. Star 1 is dimmer in apparent brightness than Star 2 by a factor of 100. What can you conclude, assuming there is no absorption of either star's light by interstellar gas or dust?

Accepted Answer

A)  Without first knowing the distances to these stars, you cannot draw any conclusions about how their true luminosities compare to each other. 
B)  The luminosity of Star 1 is a factor of 100 less than the luminosity of Star 2. 
C)  Star 1 is 100 times more distant than Star 2. 
D)  Star 1 is 100 times nearer than Star 2. 
E)  Star 1 is 10 times more distant than Star 2. 
A)  Without first knowing the distances to these stars, you cannot draw any conclusions about how their true luminosities compare to each other. 
B)  The luminosity of Star 1 is a factor of 100 less than the luminosity of Star 2. 
C)  Star 1 is 100 times more distant than Star 2. 
D)  Star 1 is 100 times nearer than Star 2. 
E)  Star 1 is 10 times more distant than Star 2.

Question 13

The spectral sequence, in order of decreasing temperature, is

Accepted Answer

A)  OFBAGKM. 
B)  OBAGFKM. 
C)  OBAFGKM. 
D)  ABFGKMO. 
E)  BAGFKMO. 
A)  OFBAGKM. 
B)  OBAGFKM. 
C)  OBAFGKM. 
D)  ABFGKMO. 
E)  BAGFKMO.

Question 14

On a Hertzsprung-Russell diagram, where would you find red giant stars?

Accepted Answer

A)  upper right 
B)  lower right 
C)  upper left 
D)  lower left 
A)  upper right 
B)  lower right 
C)  upper left 
D)  lower left

Question 15

We can measure the radii of stars in eclipsing binary systems.

Accepted Answer

A) True 
 B)False

Question 16

The following questions refer to the sketch of the H-R diagram below. Choose the best answer in each case. Note that choice (a) refers to the entire main sequence, while (c) and (d) refer to only small parts of the main sequence. If choice (c) or (d) offers a better answer to a particular question than (a) , use the best choice. You may use the same choice more than once.
 
-Which group includes the Sun?

Accepted Answer

The answer of The following questions refer to the sketch...

Question 17

If a star has a mass of 10 solar masses and a luminosity of 10,000 solar luminosities, how long is its lifetime? (The Sun's lifetime is 10 billion years.)

Accepted Answer

A)  10 million years 
B)  1 million years 
C)  100 trillion years 
D)  100 billion years 
A)  10 million years 
B)  1 million years 
C)  100 trillion years 
D)  100 billion years

Question 18

A scientist claims that all red main sequence stars are 1 billion years old. Which of the following, if true, would prove that this claim is false?

Accepted Answer

A)  The discovery of a red main sequence star in a star cluster where all the other stars are red giants or red supergiants. 
B)  Stellar evolution theory predicts that the main sequence lifetime of red stars can be as long as 100 billion years. 
C)  The minimum lifespan of a red main sequence star is estimated to be 10 billion years. 
D)  The discovery of a red main sequence star in a star cluster where the main sequence turnoff is about that of the Sun. 
A)  The discovery of a red main sequence star in a star cluster where all the other stars are red giants or red supergiants. 
B)  Stellar evolution theory predicts that the main sequence lifetime of red stars can be as long as 100 billion years. 
C)  The minimum lifespan of a red main sequence star is estimated to be 10 billion years. 
D)  The discovery of a red main sequence star in a star cluster where the main sequence turnoff is about that of the Sun.

Question 19

The axes on a Hertzsprung-Russell (H-R) diagram represent ________.

Accepted Answer

A)  luminosity and surface temperature 
B)  mass and luminosity 
C)  luminosity and apparent brightness 
D)  mass and radius 
A)  luminosity and surface temperature 
B)  mass and luminosity 
C)  luminosity and apparent brightness 
D)  mass and radius

Question 20

The choices below each describe the appearance of an H-R diagram for a different star cluster. Which cluster is the youngest?

Accepted Answer

A)  The diagram shows main-sequence stars of every spectral type except O, along with a few giants and supergiants. 
B)  The diagram shows main-sequence stars of spectral types G, K, and M, along with numerous giants and white dwarfs. 
C)  The diagram shows main-sequence stars of all the spectral types except O and B, along with a few giants and supergiants. 
D)  The diagram shows no main-sequence stars at all, but it has numerous supergiants and white dwarfs. 
A)  The diagram shows main-sequence stars of every spectral type except O, along with a few giants and supergiants. 
B)  The diagram shows main-sequence stars of spectral types G, K, and M, along with numerous giants and white dwarfs. 
C)  The diagram shows main-sequence stars of all the spectral types except O and B, along with a few giants and supergiants. 
D)  The diagram shows no main-sequence stars at all, but it has numerous supergiants and white dwarfs.

Most stars on the main sequence fuse hydrogen into helium in their cores, but some do not.

Two stars have the same luminosity. Star X is spectral type F, while Star Y is spectral type K. Star X must be larger in radius than Star Y.

A 10 solar mass star is about ten times more luminous than a 1 solar mass star.

Which of the following statements comparing open and globular star clusters is not true?

If the distance between us and a star is doubled, with everything else remaining the same, its luminosity

Star A is identical to Star B, except that Star A is twice as far from us as Star B. Therefore:

On the main sequence, stars obtain their energy

Which stellar spectral type has strong molecular absorption lines in its optical spectrum?

A star of spectral type G lives approximately how long on the main sequence?

Which star is the hottest star?

Ten parsecs is about ________.

You see two main-sequence stars with the same spectral type. Star 1 is dimmer in apparent brightness than Star 2 by a factor of 100. What can you conclude, assuming there is no absorption of either star's light by interstellar gas or dust?

The spectral sequence, in order of decreasing temperature, is

On a Hertzsprung-Russell diagram, where would you find red giant stars?

We can measure the radii of stars in eclipsing binary systems.

If a star has a mass of 10 solar masses and a luminosity of 10,000 solar luminosities, how long is its lifetime? (The Sun's lifetime is 10 billion years.)

A scientist claims that all red main sequence stars are 1 billion years old. Which of the following, if true, would prove that this claim is false?

The axes on a Hertzsprung-Russell (H-R) diagram represent ________.

The choices below each describe the appearance of an H-R diagram for a different star cluster. Which cluster is the youngest?

Our Place in 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 Planetary Systems: Our Solar System and Beyond

Earth and the Terrestrial Worlds

Jovian Planet Systems

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

Our Star

Star Stuff

Bizarre Stellar Graveyard

Our Galaxy

Galaxies and the Foundation of Modern Cosmology

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

The Beginning of Time

Life in the Universe

Filters

Exam 11: Surveying the Stars

Most stars on the main sequence fuse hydrogen into helium in their cores, but some do not.

Two stars have the same luminosity. Star X is spectral type F, while Star Y is spectral type K. Star X must be larger in radius than Star Y.

A 10 solar mass star is about ten times more luminous than a 1 solar mass star.

Which of the following statements comparing open and globular star clusters is not true?

If the distance between us and a star is doubled, with everything else remaining the same, its luminosity

Star A is identical to Star B, except that Star A is twice as far from us as Star B. Therefore:

On the main sequence, stars obtain their energy

Which stellar spectral type has strong molecular absorption lines in its optical spectrum?

A star of spectral type G lives approximately how long on the main sequence?

Which star is the hottest star?

Ten parsecs is about ________.

You see two main-sequence stars with the same spectral type. Star 1 is dimmer in apparent brightness than Star 2 by a factor of 100. What can you conclude, assuming there is no absorption of either star's light by interstellar gas or dust?

The spectral sequence, in order of decreasing temperature, is

On a Hertzsprung-Russell diagram, where would you find red giant stars?

We can measure the radii of stars in eclipsing binary systems.

If a star has a mass of 10 solar masses and a luminosity of 10,000 solar luminosities, how long is its lifetime? (The Sun's lifetime is 10 billion years.)

A scientist claims that all red main sequence stars are 1 billion years old. Which of the following, if true, would prove that this claim is false?

The axes on a Hertzsprung-Russell (H-R) diagram represent ________.

The choices below each describe the appearance of an H-R diagram for a different star cluster. Which cluster is the youngest?

Our Place in 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 Planetary Systems: Our Solar System and Beyond

Earth and the Terrestrial Worlds

Jovian Planet Systems

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

Our Star

Star Stuff

Bizarre Stellar Graveyard

Our Galaxy

Galaxies and the Foundation of Modern Cosmology

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

The Beginning of Time

Life in the Universe

Filters