Question 1

We can measure the radii of stars in an eclipsing binary system,in addition to the masses.

Accepted Answer

A) True 
 B)False  True

Question 2

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

Accepted Answer

A) True 
 B)False  False

Question 3

Refer to the choices in the table for the following questions.
  
-Which star appears brightest in the sky?

Accepted Answer

C

Question 4

If the distance between us and a star is doubled,the apparent brightness is decreased by a factor of four.

Accepted Answer

A) True 
 B)False

Question 5

Since all stars begin their lives with the same basic composition,what characteristic most determines how they will differ?

Accepted Answer

A) location where they are formed 
B) time they are formed 
C) luminosity they are formed with 
D) mass they are formed with 
E) color they are formed with 
A) location where they are formed 
B) time they are formed 
C) luminosity they are formed with 
D) mass they are formed with 
E) color they are formed with

Question 6

The spectral sequence sorts stars according to

Accepted Answer

A) mass. 
B) surface temperature. 
C) luminosity. 
D) core temperature. 
E) radius. 
A) mass. 
B) surface temperature. 
C) luminosity. 
D) core temperature. 
E) radius.

Question 7

Suppose our Sun were suddenly replaced by a supergiant star.Which of the following would be true?

Accepted Answer

A) Earth would be inside the supergiant. 
B) The supergiant's surface temperature would be much hotter than the surface temperature of our Sun. 
C) Earth would fly off into interstellar space. 
D) The supergiant would appear as large as the full Moon in our sky. 
A) Earth would be inside the supergiant. 
B) The supergiant's surface temperature would be much hotter than the surface temperature of our Sun. 
C) Earth would fly off into interstellar space. 
D) The supergiant would appear as large as the full Moon in our sky.

Question 8

Star A has an apparent magnitude of 3 and Star B has an apparent magnitude of 5.Which star is brighter in our sky?

Accepted Answer

A) Star A 
B) Star B 
C) The two stars have the same brightness in our sky,but Star A is closer to us than Star B. 
D) There is not enough information to answer the question. 
A) Star A 
B) Star B 
C) The two stars have the same brightness in our sky,but Star A is closer to us than Star B. 
D) There is not enough information to answer the question.

Question 9

The following questions refer to the sketch of the H-R diagram below.Please choose the best answer in each case,i.e. ,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 represents hydrogen-burning stars with the shortest lifetimes?

Accepted Answer

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

Question 10

Astronomers can measure a star's mass in only certain cases.Which one of the following cases might allow astronomers to measure a star's mass?

Accepted Answer

A) The star is a member of a binary star system. 
B) The star is of spectral type G. 
C) The star is of spectral type A. 
D) We know the star's luminosity and distance. 
A) The star is a member of a binary star system. 
B) The star is of spectral type G. 
C) The star is of spectral type A. 
D) We know the star's luminosity and distance.

Question 11

How did astronomers discover the relationship between spectral type and mass for main-sequence stars?

Accepted Answer

A) by using computer models of hydrogen fusion and stellar structure 
B) by measuring stellar radii with very powerful telescopes 
C) by comparing stars with the same spectral type but different luminosities 
D) by measuring the masses and spectral types of main-sequence stars in binary systems 
A) by using computer models of hydrogen fusion and stellar structure 
B) by measuring stellar radii with very powerful telescopes 
C) by comparing stars with the same spectral type but different luminosities 
D) by measuring the masses and spectral types of main-sequence stars in binary systems

Question 12

Which of the following statements about apparent and absolute magnitudes is true?

Accepted Answer

A) The magnitude system that we use now is based on a system used by the ancient Greeks over 2,000 years ago that classified stars by how bright they appeared. 
B) A star with apparent magnitude 1 is brighter than one with apparent magnitude 2. 
C) The absolute magnitude of a star is another measure of its luminosity. 
D) A star's absolute magnitude is the apparent magnitude it would have if it were at a distance of 10 parsecs from Earth. 
E) All of the above are true. 
A) The magnitude system that we use now is based on a system used by the ancient Greeks over 2,000 years ago that classified stars by how bright they appeared. 
B) A star with apparent magnitude 1 is brighter than one with apparent magnitude 2. 
C) The absolute magnitude of a star is another measure of its luminosity. 
D) A star's absolute magnitude is the apparent magnitude it would have if it were at a distance of 10 parsecs from Earth. 
E) All of the above are true.

Question 13

Refer to the choices in the table for the following questions.
  
-Which star is most similar to the Sun?

Accepted Answer

The answer of Refer to the choices in the table...

Question 14

According to the inverse square law of light,how will the apparent brightness of an object change if its distance to us triples?

Accepted Answer

A) Its apparent brightness will increase by a factor of 9. 
B) Its apparent brightness will decrease by a factor of 9. 
C) Its apparent brightness will increase by a factor of 3. 
D) Its apparent brightness will decrease by a factor of 3. 
A) Its apparent brightness will increase by a factor of 9. 
B) Its apparent brightness will decrease by a factor of 9. 
C) Its apparent brightness will increase by a factor of 3. 
D) Its apparent brightness will decrease by a factor of 3.

Question 15

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

Question 16

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

Accepted Answer

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

Question 17

On a Hertzsprung-Russell diagram,where would we 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 18

Earth is about 150 million km from the Sun,and the apparent brightness of the Sun in our sky is about 1,300 watts per square meter.Determine the apparent brightness we would measure for the Sun if we were located half Earth's distance from the Sun.

Accepted Answer

The Sun would appear four time

Question 19

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

Accepted Answer

A) True 
 B)False

Question 20

Which cluster is 10 billion years old?

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Exam 15: Surveying the Stars

We can measure the radii of stars in an eclipsing binary system,in addition to the masses.

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

Refer to the choices in the table for the following questions. -Which star appears brightest in the sky?

If the distance between us and a star is doubled,the apparent brightness is decreased by a factor of four.

Since all stars begin their lives with the same basic composition,what characteristic most determines how they will differ?

The spectral sequence sorts stars according to

Suppose our Sun were suddenly replaced by a supergiant star.Which of the following would be true?

Star A has an apparent magnitude of 3 and Star B has an apparent magnitude of 5.Which star is brighter in our sky?

Astronomers can measure a star's mass in only certain cases.Which one of the following cases might allow astronomers to measure a star's mass?

How did astronomers discover the relationship between spectral type and mass for main-sequence stars?

Which of the following statements about apparent and absolute magnitudes is true?

Refer to the choices in the table for the following questions. -Which star is most similar to the Sun?

According to the inverse square law of light,how will the apparent brightness of an object change if its distance to us triples?

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

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

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

Earth is about 150 million km from the Sun,and the apparent brightness of the Sun in our sky is about 1,300 watts per square meter.Determine the apparent brightness we would measure for the Sun if we were located half Earth's distance from the Sun.

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

Which cluster is 10 billion years old?

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 and Matter: Reading Messages from the Cosmos

Telescopes: Portals of Discovery

Our Planetary System

Formation of the Solar System

Planetary Geology: Earth and the Other Terrestrial Worlds

Planetary Atmospheres: Earth and the Other Terrestrial Worlds

Jovian Planet Systems

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

Other Planetary Systems: The New Science of Distant Worlds

Our Star

Star Birth

Star Stuff

The Bizarre Stellar Graveyard

Our Galaxy

Galaxies and the Foundations of Modern Cosmology

Galaxy Evolution

The Birth of the Universe

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

Life in the Universe

Celestial Timekeeping and Navigation

Space and Time

Spacetime and Gravity

Building Blocks of the Universe

Filters