Question 1

Sirius is a star with spectral type A star and Rigel is a star with spectral type B star. What can we conclude?

Accepted Answer

A)   Rigel has a higher surface temperature than Sirius.
B)   Rigel has a higher core temperature than Sirius.
C)   Sirius has a higher core temperature than Rigel.
D)   Sirius has a higher surface temperature than Rigel.E) B) and D)
F) All of the above A

Question 2

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

Question 3

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 represents stars of the smallest radii?

Accepted Answer

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

Question 4

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.E) A) and D)
F) B) and C)

Question 5

How is the lifetime of a star related to its mass?

Accepted Answer

A)   More massive stars live much shorter lives than less massive stars.
B)   More massive stars live slightly shorter lives than less massive stars.
C)   More massive stars live much longer lives than less massive stars.
D)   More massive stars live slightly longer lives than less massive stars.E) C) and D)
F) A) and C) A

Question 6

All stars are born with the same basic composition, yet stars can look quite different from one another. Which two factors primarily determine the characteristics of a star?

Accepted Answer

A)   Its mass and its stage of life
B)   Its apparent brightness and its distance
C)   Its age and its location in the galaxy
D)   Its mass and its surface temperature
E)   Its apparent brightness and its luminosityF) All of the above
G) B) and D)

Question 7

Which of the following correctly states the relationship between the apparent brightness, luminosity, and distance of a star?

Accepted Answer

A)   luminosity = 
B)   apparent brightness =   luminosity 4π×( distance ) 2 \frac{	ext { luminosity }}{4 \pi 	imes(	ext { distance }) ^{2}} 4π×( distance ) 2 luminosity ​ 
C)   apparent brightness = luminosity × 4π × (distance)  ²
D)   distance =  E) None of the above
F) A) and D)

Question 8

An O-star has a hotter surface temperature than the Sun. Therefore, compared to the Sun,

Accepted Answer

A)   its emission peaks in the blue part of the spectrum.
B)   it emits at about the same wavelengths as the Sun (similar peak)  but it is much brighter.
C)   it emits at about the same wavelengths as the Sun (similar peak)  but it is much fainter.
D)   its emission peaks in the infrared part of the spectrum.E) A) and D)
F) A) and C)

Question 9

Which main sequence star has the lowest mass?

Accepted Answer

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

Question 10

Which main sequence star will have the shortest lifetime?

Accepted Answer

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

Question 11

From hottest to coolest, the order of the spectral types of stars is ________.

Accepted Answer

A)   OBAFGKM
B)   OBAGFKM
C)   ABFGKMO
D)   OMKGFBA
E)   ABCDEFGF) A) and E)
G) B) and E)

Question 12

Two stars, Fred and Barney, are of the same size. Fred has spectral type F, while Barney has spectral type B. Which one is more luminous?

Accepted Answer

Barney has a hotter surface te...

Question 13

Which of the following statements about spectral types of stars is true?

Accepted Answer

A)   The spectral type of a star can be used to determine its surface temperature.
B)   The spectral type of a star can be used to determine its color.
C)   A star with spectral type A is cooler than a star with spectral type B.
D)   A star with spectral type F2 is hotter than a star with spectral type F3.
E)   All of the above are true.F) C) and E)
G) B) and D)

Question 14

The 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 the earth's distance from the Sun.

Accepted Answer

The Sun would appear four time...

Question 15

The sketch above shows groups of stars on the H-R diagram, labeled (a)  through (e) ; note that (a)  represents the entire main sequence while (c)  and (d)  represent only small parts of the main sequence. Which group represents stars that are cool and dim?

Accepted Answer

A)   a
B)   b
C)   c
D)   d
E)   eF) C) and E)
G) A) and B) D

Question 16

You observe a star cluster with a main-sequence turn-off point at spectral type G2 (the same spectral type as the Sun) . What is the age of this star cluster?

Accepted Answer

A)   10,000 years.
B)   4.6 billion years.
C)   10 billion years.
D)   100 billion years.
E)   You also need to know the luminosity class of the turn-off point to determine the age.F) B) and E)
G) B) and D)

Question 17

Which of the following best describes the axes of a Hertzsprung-Russell (H-R)  diagram?

Accepted Answer

A)   surface temperature on the horizontal axis and luminosity on the vertical axis
B)   mass on the horizontal axis and luminosity on the vertical axis
C)   surface temperature on the horizontal axis and radius on the vertical axis
D)   mass on the horizontal axis and stellar age on the vertical axis
E)   interior temperature on the horizontal axis and mass on the vertical axisF) All of the above
G) A) and B)

Question 18

On a Hertzsprung-Russell diagram, where would you find stars that have the largest radii?

Accepted Answer

A)   upper right
B)   lower right
C)   upper left
D)   lower leftE) A) and D)
F) C) and D)

Question 19

If the Sun-Earth separation was 10 AU instead of 1 AU, what would the ﬂux of sunlight (energy per second per square meter)  be at the Earth, compared to what it is today?

Accepted Answer

A)   10 times less
B)   About 3.16 (or the square root of 10)  times less
C)   10 times more
D)   100 times less
E)   100 times moreF) All of the above
G) B) and E)

Question 20

What can we infer, at least roughly, from a star's luminosity class?

Accepted Answer

A)   Its size (radius) 
B)   Its mass
C)   Its age in years
D)   Its surface temperatureE) All of the above
F) None of the above

Exam 11: Surveying the Stars

Sirius is a star with spectral type A star and Rigel is a star with spectral type B star. What can we conclude?

Correct Answer
verified
A

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

Correct Answer
verified

Correct Answer
verified

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

Correct Answer
verified

How is the lifetime of a star related to its mass?

Correct Answer
verified
A

All stars are born with the same basic composition, yet stars can look quite different from one another. Which two factors primarily determine the characteristics of a star?

Correct Answer
verified

Which of the following correctly states the relationship between the apparent brightness, luminosity, and distance of a star?

Correct Answer
verified

An O-star has a hotter surface temperature than the Sun. Therefore, compared to the Sun,

Correct Answer
verified

Which main sequence star has the lowest mass?

Correct Answer
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Which main sequence star will have the shortest lifetime?

Correct Answer
verified

From hottest to coolest, the order of the spectral types of stars is ________.

Correct Answer
verified

Two stars, Fred and Barney, are of the same size. Fred has spectral type F, while Barney has spectral type B. Which one is more luminous?

Correct Answer
verified
Barney has a hotter surface te...
View Answer

Which of the following statements about spectral types of stars is true?

Correct Answer
verified

The 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 the earth's distance from the Sun.

Correct Answer
verified
The Sun would appear four time...
View Answer

The sketch above shows groups of stars on the H-R diagram, labeled (a) through (e) ; note that (a) represents the entire main sequence while (c) and (d) represent only small parts of the main sequence. Which group represents stars that are cool and dim?

Correct Answer
verified
D

You observe a star cluster with a main-sequence turn-off point at spectral type G2 (the same spectral type as the Sun) . What is the age of this star cluster?

Correct Answer
verified

Which of the following best describes the axes of a Hertzsprung-Russell (H-R) diagram?

Correct Answer
verified

On a Hertzsprung-Russell diagram, where would you find stars that have the largest radii?

Correct Answer
verified

If the Sun-Earth separation was 10 AU instead of 1 AU, what would the ﬂux of sunlight (energy per second per square meter) be at the Earth, compared to what it is today?

Correct Answer
verified

What can we infer, at least roughly, from a star's luminosity class?

Correct Answer
verified

Exam 11: Surveying the Stars

Sirius is a star with spectral type A star and Rigel is a star with spectral type B star. What can we conclude?

Correct AnswerverifiedA

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

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

How is the lifetime of a star related to its mass?

Correct AnswerverifiedA

All stars are born with the same basic composition, yet stars can look quite different from one another. Which two factors primarily determine the characteristics of a star?

Correct AnswerverifiedShow Answer

Which of the following correctly states the relationship between the apparent brightness, luminosity, and distance of a star?

Correct AnswerverifiedShow Answer

An O-star has a hotter surface temperature than the Sun. Therefore, compared to the Sun,

Correct AnswerverifiedShow Answer

Which main sequence star has the lowest mass?

Correct AnswerverifiedShow Answer

Which main sequence star will have the shortest lifetime?

Correct AnswerverifiedShow Answer

From hottest to coolest, the order of the spectral types of stars is ________.

Correct AnswerverifiedShow Answer

Two stars, Fred and Barney, are of the same size. Fred has spectral type F, while Barney has spectral type B. Which one is more luminous?

Correct AnswerverifiedBarney has a hotter surface te...View AnswerShow Answer

Which of the following statements about spectral types of stars is true?

Correct AnswerverifiedShow Answer

The 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 the earth's distance from the Sun.

Correct AnswerverifiedThe Sun would appear four time...View AnswerShow Answer

The sketch above shows groups of stars on the H-R diagram, labeled (a) through (e) ; note that (a) represents the entire main sequence while (c) and (d) represent only small parts of the main sequence. Which group represents stars that are cool and dim?

Correct AnswerverifiedD

You observe a star cluster with a main-sequence turn-off point at spectral type G2 (the same spectral type as the Sun) . What is the age of this star cluster?

Correct AnswerverifiedShow Answer

Which of the following best describes the axes of a Hertzsprung-Russell (H-R) diagram?

Correct AnswerverifiedShow Answer

On a Hertzsprung-Russell diagram, where would you find stars that have the largest radii?

Correct AnswerverifiedShow Answer

If the Sun-Earth separation was 10 AU instead of 1 AU, what would the ﬂux of sunlight (energy per second per square meter) be at the Earth, compared to what it is today?

Correct AnswerverifiedShow Answer

What can we infer, at least roughly, from a star's luminosity class?

Correct AnswerverifiedShow Answer

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A

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A

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Barney has a hotter surface te...
View Answer

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The Sun would appear four time...
View Answer

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D

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