Question 1

What kind of gas cloud is most likely to give birth to stars?

Accepted Answer

A)   A cold, dense gas cloud
B)   A hot, dense gas cloud
C)   A cold, low-density gas cloud
D)   A hot, low-density gas cloudE) B) and C)
F) A) and D)

Question 2

Helium fusion results in the production of

Accepted Answer

A)   hydrogen.
B)   oxygen.
C)   carbon.
D)   nitrogen.
E)   iron.F) A) and B)
G) A) and E)

Question 3

Based on its main-sequence turnoff point, the age of this cluster is

Accepted Answer

A)   less than 1 billion years.
B)   about 1 billion years.
C)   about 4.5 billion years.
D)   about 10 billion years.
E)   more than 15 billion years.F) C) and D)
G) B) and D) D

Question 4

Which of the following lists the stages of life for a low-mass star in the correct order?

Accepted Answer

A)   Protostar, main-sequence star, red giant, planetary nebula, white dwarf
B)   Protostar, main-sequence star, red giant, supernova, neutron star
C)   Protostar, main-sequence star, planetary nebula, red giant
D)   Main-sequence star, white dwarf, red giant, planetary nebula, protostarE) A) and D)
F) A) and B)

Question 5

Our Sun is considered to be a ________.

Accepted Answer

A)   low-mass star
B)   intermediate-mass star
C)   high-mass star
D)   brown dwarfE) C) and D)
F) B) and C)

Question 6

Which of the following sequences correctly describes the stages of life for a low-mass star?

Accepted Answer

A)   red giant, protostar, main-sequence, white dwarf
B)   white dwarf, main-sequence, red giant, protostar
C)   protostar, red giant, main-sequence, white dwarf
D)   protostar, main-sequence, white dwarf, red giant
E)   protostar, main-sequence, red giant, white dwarfF) C) and D)
G) B) and C)

Question 7

Compared to the star it evolved from, a white dwarf is

Accepted Answer

A)   hotter and brighter.
B)   hotter and dimmer.
C)   cooler and brighter.
D)   cooler and dimmer.
E)   the same temperature and brightness.F) C) and D)
G) C) and E)

Question 8

You discover a binary star system in which one star is a 15 MSᵤn main-sequence star and the other is a 10 MSᵤn giant. How do we think that a star system such as this might have come to exist?

Accepted Answer

A)   The giant must once have been the more massive star, but is now less massive because it transferred some of its mass to its companion.
B)   Although both stars probably formed from the same clump of gas, the more massive one must have had its birth slowed so that it became a main sequence stars millions of years later than its less massive companion.
C)   The two stars probably were once separate, but became a binary when a close encounter allowed their mutual gravity to pull them together.
D)   The two stars are simply evolving normally and independently, and one has become a giant before the other.E) All of the above
F) C) and D)

Question 9

(Use diagram of abundance vs atomic number)  What process best explains the observed pattern of abundances of elements with atomic numbers between 6 and 20?

Accepted Answer

A)   Fusion reactions with neutrons
B)   Radioactive decay of nuclei with odd numbers of protons
C)   Fusion reactions with helium nuclei
D)   Fusion reactions with hydrogen nucleiE) C) and D)
F) B) and C)

Question 10

Which event marks the beginning of a supernova?

Accepted Answer

A)   the onset of helium burning after a helium flash in a star with mass comparable to that of the Sun
B)   the sudden outpouring of X-rays from a newly formed accretion disk
C)   the sudden collapse of an iron core into a compact ball of neutrons
D)   the beginning of neon burning in an extremely massive star
E)   the expansion of a low-mass star into a red giantF) None of the above
G) B) and D)

Question 11

As a solar mass protostar moves on to the main sequence,

Accepted Answer

A)   its surface temperature and luminosity increase.
B)   its surface temperature increases and its luminosity decreases.
C)   its surface temperature and luminosity decrease.
D)   its surface temperature decreases and its luminosity increases.
E)   its surface temperature and luminosity remain the same.F) B) and E)
G) C) and E) B

Question 12

Most interstellar clouds remain stable in size because the force of gravity is opposed by ________ within the cloud.

Accepted Answer

A)   thermal pressure
B)   degeneracy pressure
C)   radiation pressure
D)   stellar windsE) A) and B)
F) C) and D)

Question 13

Generally speaking, how does the surface temperature and luminosity of a protostar compare to the surface temperature and luminosity of the main-sequence star it becomes?

Accepted Answer

A)   A main-sequence star is hotter and dimmer than it was as a protostar.
B)   A main-sequence star is hotter and brighter than it was as a protostar.
C)   A main-sequence star is cooler and dimmer than it was as a protostar.
D)   A main-sequence star is cooler and brighter than it was as a protostar.E) A) and C)
F) B) and D)

Question 14

Observations show that elements with atomic mass numbers divisible by 4 (such as oxygen-16, neon-20, and magnesium-24)  tend to be more abundant in the universe than elements with atomic mass numbers in between. Why do we think this is the case?

Accepted Answer

A)   At the end of a high-mass star's life, it produces new elements through a series of helium capture reactions.
B)   The apparent pattern is thought to be a random coincidence.
C)   Elements with atomic mass numbers divisible by 4 tend to be more stable than elements in between.
D)   This pattern in elemental abundances was apparently determined during the first few minutes after the Big Bang.E) B) and C)
F) All of the above

Question 15

This diagram represents the life track of a 1 solar mass star. Refer to the life stages labeled with roman numerals. During which stage does the star have an inert (non-burning)  carbon core surrounded by shells of helium and hydrogen burning?

Accepted Answer

A)   viii
B)   iv
C)   vi
D)   iii
E)   iiF) A) and B)
G) C) and D)

Question 16

Algol consist of a 3.7 MSun main-sequence star and a 0.8 MSun subgiant. Why does this seem surprising, at least at first?

Accepted Answer

A)   The two stars should be the same age, so we'd expect the subgiant to be more massive than the main-sequence star.
B)   The two stars in a binary system should both be at the same stage of life; that is, they should either both be main sequence stars or both be subgiants.
C)   It doesn't make sense to find a subgiant in a binary star system.
D)   A star with a mass of 3.7 M Sᵤn is too big to be a main sequence star.E) B) and D)
F) All of the above

Question 17

Choose from the list below for the following questions. You may use a choice more than once.
-When a 1-solar-mass star stabilizes as a giant for about a billion years, which method of energy generation occurs in its central core?

Accepted Answer

A)  H fusion by the proton-proton chain
B)  H fusion by the CNO cycle
C)  helium fusion
D)  matter-antimatter annihilation
E)  gravitational contractionF) D) and E)
G) B) and E)

Question 18

Where does gold (the element)  come from?

Accepted Answer

A)   It is produced during the supernova explosions of high-mass stars.
B)   It is produced by mass transfer in close binaries.
C)   It is produced during the late stages of fusion in low-mass stars.
D)   It was produced during the Big Bang.E) A) and D)
F) A) and C)

Question 19

You discover a binary star system in which one member is a 15 solar mass main-sequence star and the other star is a 10 solar mass giant star. Why should you be surprised, at least at first?

Accepted Answer

A)   It doesn't make sense to find a giant in a binary star system.
B)   The odds of ever finding two such massive stars in the same binary system are so small as to make it inconceivable.
C)   The two stars in a binary system should both be at the same point in stellar evolution; that is, they should either both be main-sequence stars or both be giants.
D)   The two stars should be the same age, so the more massive one should have become a giant first.
E)   A star with a mass of 15 solar masses is too big to be a main-sequence star.F) A) and E)
G) A) and D)

Question 20

Which of the following statements about brown dwarfs is not true?

Accepted Answer

A)   Brown dwarfs eventually collapse to become white dwarfs.
B)   Brown dwarfs are supported against gravity by degeneracy pressure, which does not depend on the object's temperature.
C)   Brown dwarfs form like ordinary stars but are too small to sustain nuclear fusion in their cores.
D)   All brown dwarfs have masses less than about 8% that of our Sun.E) A) and B)
F) None of the above A

Exam 12: Star Stuff

What kind of gas cloud is most likely to give birth to stars?

Correct AnswerverifiedShow Answer

Helium fusion results in the production of

Correct AnswerverifiedShow Answer

Based on its main-sequence turnoff point, the age of this cluster is

Correct AnswerverifiedD

Which of the following lists the stages of life for a low-mass star in the correct order?

Correct AnswerverifiedShow Answer

Our Sun is considered to be a ________.

Correct AnswerverifiedShow Answer

Which of the following sequences correctly describes the stages of life for a low-mass star?

Correct AnswerverifiedShow Answer

Compared to the star it evolved from, a white dwarf is

Correct AnswerverifiedShow Answer

You discover a binary star system in which one star is a 15 MSᵤn main-sequence star and the other is a 10 MSᵤn giant. How do we think that a star system such as this might have come to exist?

Correct AnswerverifiedShow Answer

(Use diagram of abundance vs atomic number) What process best explains the observed pattern of abundances of elements with atomic numbers between 6 and 20?

Correct AnswerverifiedShow Answer

Which event marks the beginning of a supernova?

Correct AnswerverifiedShow Answer

As a solar mass protostar moves on to the main sequence,

Correct AnswerverifiedB

Most interstellar clouds remain stable in size because the force of gravity is opposed by ________ within the cloud.

Correct AnswerverifiedShow Answer

Generally speaking, how does the surface temperature and luminosity of a protostar compare to the surface temperature and luminosity of the main-sequence star it becomes?

Correct AnswerverifiedShow Answer

Observations show that elements with atomic mass numbers divisible by 4 (such as oxygen-16, neon-20, and magnesium-24) tend to be more abundant in the universe than elements with atomic mass numbers in between. Why do we think this is the case?

Correct AnswerverifiedShow Answer

This diagram represents the life track of a 1 solar mass star. Refer to the life stages labeled with roman numerals. During which stage does the star have an inert (non-burning) carbon core surrounded by shells of helium and hydrogen burning?

Correct AnswerverifiedShow Answer

Algol consist of a 3.7 MSun main-sequence star and a 0.8 MSun subgiant. Why does this seem surprising, at least at first?

Correct AnswerverifiedShow Answer

Choose from the list below for the following questions. You may use a choice more than once. -When a 1-solar-mass star stabilizes as a giant for about a billion years, which method of energy generation occurs in its central core?

Correct AnswerverifiedShow Answer

Where does gold (the element) come from?

Correct AnswerverifiedShow Answer

You discover a binary star system in which one member is a 15 solar mass main-sequence star and the other star is a 10 solar mass giant star. Why should you be surprised, at least at first?

Correct AnswerverifiedShow Answer

Which of the following statements about brown dwarfs is not true?

Correct AnswerverifiedA

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B

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A