Question 1

Ninety percent of all stars (if plotted on an H-R diagram)  would fall into a region astronomers call:

Accepted Answer

A)   the supergiant region
B)   the main sequence
C)   the white dwarf region
D)   the visual region
E)   the twilight zoneF) D) and E)
G) A) and E)

Question 2

Which of the following characteristics of a single star (one that moves through space alone)  is it difficult to measure directly?

Accepted Answer

A)   its apparent brightness
B)   its temperature
C)   its chemical composition
D)   its mass
E)   you can't fool me, all of these are quite easy to measure directlyF) C) and E)
G) B) and C)

Question 3

Two stars that are physically associated (move together through space)  are called

Accepted Answer

A)   double stars
B)   main sequence stars
C)   brown dwarf pairs
D)   first contact stars
E)   binary starsF) A) and E)
G) A) and D)

Question 4

Measurements show a certain star has a very high luminosity (100,000 x the Sun's)  while its temperature is quite cool (3500o K) . How can this be?

Accepted Answer

A)   it must be a main sequence star
B)   it must be quite small in size
C)   it must be quite large in size
D)   it must be brown dwarf and not a regular star
E)   this must be an error in observations; no such star can existF) D) and E)
G) B) and E) C

Question 5

One of your good friends who is on a diet asks you to point out the stars with the smallest mass on an H-R diagram that you are studying. Where are you sure to find the stars with the lowest mass on any H-R diagram?

Accepted Answer

A)   among the white dwarfs
B)   among the stars at the top left of the main sequence
C)   among the stars at the bottom right of the main sequence
D)   among the supergiants
E)   stars with low mass can be located anywhere at all in the H-R diagramF) B) and C)
G) B) and D)

Question 6

In an H-R diagram, where can you see the spectral type of a star (whether it is an O type star or a G type star, for example) ?

Accepted Answer

A)   along the right (vertical axis) 
B)   along the bottom (the horizontal axis) 
C)   only in the red giant region
D)   only on the main sequence
E)   H-R diagrams have nothing to say about spectral typesF) C) and D)
G) B) and D) B

Question 7

Why can astronomers not measure the diameters of stars directly?

Accepted Answer

A)   stars are so bright, their light burns out all the delicate instruments we would use to measure their diameters
B)   all stars change their diameters regularly, growing alternately larger and smaller
C)   stars are so far away, we cannot resolve (distinguish)  their diameters
D)   stars are all in binary systems, and we can only see the combined diameter of both stars
E)   you can't fool me; measuring the diameter of any star is a relatively easy processF) D) and E)
G) C) and D)

Question 8

I am measuring the spectrum of the stars in a spectroscopic binary system. When one of the stars is moving toward the Earth in its orbit, we observe

Accepted Answer

A)   that the lines in its spectrum get brighter
B)   that the lines in its spectrum merge with the lines of the other star
C)   that it is no longer possible to learn what elements are in the star
D)   that the lines in its spectrum show a blue-shift
E)   none of the aboveF) C) and D)
G) All of the above

Question 9

Which of the following is a method for measuring the diameter of a star?

Accepted Answer

A)   watching the body of the Moon go across the star
B)   getting the light curve of an eclipsing binary star
C)   comparing the color of a star seen high above our heads and then again when it's near the horizon
D)   measuring the spectrum of a spectroscopic binary
E)   more than one of the aboveF) A) and B)
G) C) and D)

Question 10

Where on the H-R Diagram would we find stars that look red when seen through a telescope?

Accepted Answer

A)   only near the top of the diagram and never near the bottom
B)   only near the left side of the diagram and never near the right
C)   only on the right side of the diagram and never on the left
D)   only near the bottom of the diagram and never near the top
E)   anywhere in the diagramF) C) and D)
G) A) and B)

Question 11

An H-R Diagram plots the luminosity of stars against their:

Accepted Answer

A)   mass
B)   diameter
C)   surface temperature
D)   age
E)   location in the skyF) None of the above
G) B) and D)

Question 12

Which of the following has the smallest mass?

Accepted Answer

A)   a brown dwarf
B)   a planet
C)   the Sun
D)   the smallest mass star that can still have fusion of hydrogen to helium in its core
E)   you can't fool me, all the above have roughly the same massF) All of the above
G) B) and C) B

Question 13

A white dwarf, compared to a main sequence star with the same mass, would always be:

Accepted Answer

A)   larger in diameter
B)   smaller in diameter
C)   the same size in diameter
D)   younger in age
E)   less massiveF) B) and D)
G) B) and C)

Question 14

What was the first evidence that gravity outside our solar system worked the same way as it does inside?

Accepted Answer

A)   Galileo saw through his early telescope that the Milky Way consisted of many stars
B)   Herschel measured the two stars that make up the Castor system moved around each other
C)   Cannon measured different lines in the spectra of different types of stars
D)   Comet Halley returned after a 76-year absence
E)   You can't fool me, we still don't know whether gravity around other stars works the same way as it does hereF) A) and D)
G) C) and D)

Question 15

Who was the astronomer who is the "H" in H-R diagram?

Accepted Answer

A)   Hubble
B)   Humason
C)   Hertzsprung
D)   Huggins
E)   HoyleF) C) and D)
G) A) and C)

Question 16

Most of the stars we can see with the unaided eye from Earth are

Accepted Answer

A)   intrinsically fainter than the Sun
B)   very close to us (among the closest stars) 
C)   more luminous (intrinsically brighter)  than the Sun
D)   only visible to our eyes because they actually consist of three or more stars blending their light together
E)   undergoing some sort of explosion which makes their outer layers unusually brightF) All of the above
G) B) and E)

Question 17

For what type of star can astronomers measure the diameter with relative ease?

Accepted Answer

A)   visual double stars
B)   white dwarf stars
C)   main sequence stars
D)   eclipsing binary stars
E)   any star that is not a brown dwarfSection 18.4: The H-R DiagramF) A) and B)
G) A) and D)

Question 18

Some "superstars" give off more than 50,000 times the energy of the Sun. Why are there no such stars among the stars that are close to the Sun?

Accepted Answer

A)   because conditions in the "neighborhood" of the Sun only permit low-mass (low luminosity)  stars to form
B)   because such very luminous stars are extremely rare, and thus any small neighborhood in the Galaxy is unlikely to contain one of them
C)   because all stars in the vicinity of the Sun have planets, and planets rob a star of its brightness
D)   because such superstars only give off a lot of energy for a year or so, before they die
E)   because such superstars are really several hundred stars blending their light together (but so far away we can't distinguish individual stars) ; nearby stars are easy to separateF) B) and C)
G) A) and D)

Question 19

The most common kinds of stars in the Galaxy have

Accepted Answer

A)   low luminosity compared to the Sun
B)   spectra that show they contain mostly carbon
C)   enormous masses compared to the Sun
D)   diameters thousands of times greater than the Sun's
E)   a dozen or more stars in close orbit around themSection 18.2: Measuring Stellar MassesF) None of the above
G) A) and E)

Question 20

A team of astronomers discovers one of the most massive stars ever found. If this star is just settling down in that stage of its life where it will be peacefully converting hydrogen to helium in its core, where will we find it on the H-R diagram?

Accepted Answer

A)   among the supergiants, in the upper right
B)   a little bit below the Sun on the main sequence
C)   among the most brilliant of the white dwarfs, in the lower left
D)   near the very top of the main sequence, in the upper left
E)   it could be anywhere on the diagram; we would need more information to determine its placeF) A) and B)
G) A) and D)

Exam 18: The Stars: a Celestial Census

Ninety percent of all stars (if plotted on an H-R diagram) would fall into a region astronomers call:

Correct AnswerverifiedShow Answer

Which of the following characteristics of a single star (one that moves through space alone) is it difficult to measure directly?

Correct AnswerverifiedShow Answer

Two stars that are physically associated (move together through space) are called

Correct AnswerverifiedShow Answer

Measurements show a certain star has a very high luminosity (100,000 x the Sun's) while its temperature is quite cool (3500o K) . How can this be?

Correct AnswerverifiedC

One of your good friends who is on a diet asks you to point out the stars with the smallest mass on an H-R diagram that you are studying. Where are you sure to find the stars with the lowest mass on any H-R diagram?

Correct AnswerverifiedShow Answer

In an H-R diagram, where can you see the spectral type of a star (whether it is an O type star or a G type star, for example) ?

Correct AnswerverifiedB

Why can astronomers not measure the diameters of stars directly?

Correct AnswerverifiedShow Answer

I am measuring the spectrum of the stars in a spectroscopic binary system. When one of the stars is moving toward the Earth in its orbit, we observe

Correct AnswerverifiedShow Answer

Which of the following is a method for measuring the diameter of a star?

Correct AnswerverifiedShow Answer

Where on the H-R Diagram would we find stars that look red when seen through a telescope?

Correct AnswerverifiedShow Answer

An H-R Diagram plots the luminosity of stars against their:

Correct AnswerverifiedShow Answer

Which of the following has the smallest mass?

Correct AnswerverifiedB

A white dwarf, compared to a main sequence star with the same mass, would always be:

Correct AnswerverifiedShow Answer

What was the first evidence that gravity outside our solar system worked the same way as it does inside?

Correct AnswerverifiedShow Answer

Who was the astronomer who is the "H" in H-R diagram?

Correct AnswerverifiedShow Answer

Most of the stars we can see with the unaided eye from Earth are

Correct AnswerverifiedShow Answer

For what type of star can astronomers measure the diameter with relative ease?

Correct AnswerverifiedShow Answer

Some "superstars" give off more than 50,000 times the energy of the Sun. Why are there no such stars among the stars that are close to the Sun?

Correct AnswerverifiedShow Answer

The most common kinds of stars in the Galaxy have

Correct AnswerverifiedShow Answer

A team of astronomers discovers one of the most massive stars ever found. If this star is just settling down in that stage of its life where it will be peacefully converting hydrogen to helium in its core, where will we find it on the H-R diagram?

Correct AnswerverifiedShow Answer

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Measurements show a certain star has a very high luminosity (100,000 x the Sun's) while its temperature is quite cool (3500^o K) . How can this be?

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C

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B

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B

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