Question 1

Star X has an apparent magnitude of 3, and star Y has an apparent magnitude of 13. How do they compare in observed brightness?

Accepted Answer

A)  Star Y is 10,000 times brighter than star X.
B)  Star Y is 10 times brighter than star X.
C)  Star X is 10,000 times brighter than star Y.
D)  Star X is 10 times brighter than star Y.

Question 2

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)  Stellar evolution theory predicts that the main- sequence lifetime of red stars can be as long as 100 billion years.
B)  The minimum lifespan of a red main- sequence star is estimated to be 10 billion years.
C)  The discovery of a red main- sequence star in a star cluster where all the other stars are red giants or red supergiants
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 3

A stars exhibit strong hydrogen absorption lines because the surface temperature of 10,000 K is high enough to place most hydrogen in an excited, but not yet ionized, state. The transitions from this excited state then correspond to visible light wavelengths. Which of the following statements is a plausible explanation for why G stars exhibit weak hydrogen absorption lines?

Accepted Answer

A)  G stars are too cool to excite hydrogen atoms to the first energy level from which they can then absorb visible wavelengths of light.
B)  At these high temperatures, nearly all the hydrogen is ionized, and unable to interact with light.
C)  G stars contain very little hydrogen.

Question 4

On an H- R diagram, stellar masses _.

Accepted Answer

A)  are greatest in the lower left and least in the upper right
B)  are impossible to determine
C)  can be determined for main sequence stars but not for other types of stars
D)  decrease from upper left to lower right

Question 5

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

Accepted Answer

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

Question 6

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.

Question 7

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 one- third of the earth's distance from the Sun.

Accepted Answer

The Sun would appear nine time...

Question 8

A star is observed with a surface temperature of 3,000 K and a lumi nosity of 105 solar. What is the approximate radius of this star?

Accepted Answer

A)  103 solar radii
B)  10 solar radii
C)  102 solar radii
D)  The radius cannot be determined.

Question 9

What is a white dwarf?

Accepted Answer

A)  a main- sequence star of spectral type F, which tends to look white in color
B)  a star that follows a period- luminosity relation
C)  the remains of a star that ran out of fuel for nuclear fusion
D)  a type of star that produces energy by gravitational contraction

Question 10

Explain why stars displaying spectral lines of molecules must be relatively cool.

Accepted Answer

Molecules would brea...

Question 11

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

Accepted Answer

A) True 
 B)False

Question 12

You measure the parallax angle for a star to be 0.1 arcseconds. The distance to this star is

Accepted Answer

A)  0) 1 parsec.
B)  10 parsecs.
C)  0) 1 light- year.
D)  10 light- years.
E)  impossible to determine.

Question 13

How does the rate of hydrogen consumption of a main- sequence B star compare to the hydrogen consumption of the sun?

Accepted Answer

A)  A B star consumes hydrogen at a rate about 6 to 10 times faster than the sun.
B)  A B star consumes hydrogen at a rate about 107 to 108 times faster than the sun.
C)  A B star consumes hydrogen at a rate about 103 to 104 times faster than the sun.
D)  This cannot be answered using the HR diagram.

Question 14

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 of the largest radii?

Accepted Answer

A)  a
B)  b
C)  c
D)  d
E)  e

Question 15

Which of the following statements about open clusters is true?

Accepted Answer

A)  There is an approximately equal number of all types of stars in the cluster.
B)  All stars in the cluster have approximately the same mass.
C)  All stars in the cluster are approximately the same age.
D)  All stars in the cluster will evolve similarly.
E)  All stars in the cluster are approximately the same color.

Question 16

What is the approximate surface temperature of a star with weak hydrogen absorption lines and strong absorption lines of ionized calcium?

Accepted Answer

A)  4,500 K
B)  6,500 K
C)  5,500 K
D)  3,500 K

Question 17

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

Accepted Answer

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

Question 18

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

Question 19

Ten parsecs is about _.

Accepted Answer

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

Question 20

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

Accepted Answer

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

Exam 12: Surveying the Stars

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

Correct Answer
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On an H- R diagram, stellar masses _.

Correct Answer
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Ten parsecs is about _.

Correct Answer
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How does the rate of hydrogen consumption of a main- sequence B star compare to the hydrogen consumption of the sun?

Correct Answer
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Two stars have the same spectral type. Star X is in luminosity class III, while Star Y is in luminosity class V. Star X must be larger in radius than Star Y.

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

Correct Answer
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Correct Answer
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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 of the largest radii?

Correct Answer
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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 one- third of the earth's distance from the Sun.

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

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?

Correct Answer
verified

A star is observed with a surface temperature of 3,000 K and a lumi nosity of 105 solar. What is the approximate radius of this star?

Correct Answer
verified

Which of the following statements about open clusters is true?

Correct Answer
verified

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

Correct Answer
verified

Explain why stars displaying spectral lines of molecules must be relatively cool.

Correct Answer
verified
Molecules would brea...
View Answer

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.)

Correct Answer
verified

What is a white dwarf?

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

Correct Answer
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What is the approximate surface temperature of a star with weak hydrogen absorption lines and strong absorption lines of ionized calcium?

Correct Answer
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You measure the parallax angle for a star to be 0.1 arcseconds. The distance to this star is

Correct Answer
verified

Star X has an apparent magnitude of 3, and star Y has an apparent magnitude of 13. How do they compare in observed brightness?

Correct Answer
verified

Exam 12: Surveying the Stars

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

Correct AnswerverifiedShow Answer

On an H- R diagram, stellar masses _.

Correct AnswerverifiedShow Answer

Ten parsecs is about _.

Correct AnswerverifiedShow Answer

How does the rate of hydrogen consumption of a main- sequence B star compare to the hydrogen consumption of the sun?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow 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 of the largest radii?

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 one- third of the earth's distance from the Sun.

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

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?

Correct AnswerverifiedShow Answer

A star is observed with a surface temperature of 3,000 K and a lumi nosity of 105 solar. What is the approximate radius of this star?

Correct AnswerverifiedShow Answer

Which of the following statements about open clusters is true?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

Explain why stars displaying spectral lines of molecules must be relatively cool.

Correct AnswerverifiedMolecules would brea...View AnswerShow Answer

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.)

Correct AnswerverifiedShow Answer

What is a white dwarf?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

What is the approximate surface temperature of a star with weak hydrogen absorption lines and strong absorption lines of ionized calcium?

Correct AnswerverifiedShow Answer

You measure the parallax angle for a star to be 0.1 arcseconds. The distance to this star is

Correct AnswerverifiedShow Answer

Star X has an apparent magnitude of 3, and star Y has an apparent magnitude of 13. How do they compare in observed brightness?

Correct AnswerverifiedShow Answer

Correct Answer
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Correct Answer
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The Sun would appear nine time...
View Answer

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Molecules would brea...
View Answer

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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