Question 1

Although some photographs show what looks like jets of material near many young stars, we now know that these "jets" actually represent gas from the surrounding nebula that is falling onto the stars.

Accepted Answer

A) True 
 B)False

Question 2

Most interstellar dust grains

Accepted Answer

A)   were produced in the Big Bang.
B)   are produced in the interstellar medium.
C)   are produced in the atmospheres of red giant stars.
D)   are produced in supernova explosions.
E)   are produced in the cores of low-mass starsF) C) and E)
G) B) and D)

Question 3

When does a protostar become a main-sequence star?

Accepted Answer

A)   When the rate of hydrogen fusion becomes high enough to balance the rate at which the star radiates energy into space
B)   When a piece of a molecular cloud first begins to contract into a star
C)   When it becomes luminous enough to emit thermal radiation
D)   At the instant that the first hydrogen fusion reactions occur in the protostar's coreE) B) and D)
F) B) and C)

Question 4

Approximately what core temperature is required before hydrogen fusion can begin in a star?

Accepted Answer

A)   10 million K
B)   10,000 K
C)   10 trillion K
D)   10 billion K
E)   1 billion KF) B) and E)
G) A) and B)

Question 5

Explain how some stars form in binary systems.

Accepted Answer

As a molecular cloud contracts, it break...

Question 6

Choose from the list below for the following questions. You may use a choice more than once.
-Which method of energy generation is used by the Sun today?

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) A) and C)
G) A) and E)

Question 7

Choose from the list below for the following questions. You may use a choice more than once.
-Which method of energy generation provides the source of energy for a protostar?

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) A) and C)
G) B) and D)

Question 8

Which of the following statements about various stages of core nuclear burning (hydrogen, helium, carbon, and so on)  in a high-mass star is not true?

Accepted Answer

A)   Each successive stage lasts for approximately the same amount of time.
B)   As each stage ends, the core shrinks and heats further.
C)   Each successive stage creates an element with a higher atomic number and atomic mass number.
D)   As each stage ends, the reactions that occurred in previous stages continue in shells around the core.E) None of the above
F) C) and D)

Question 9

Briefly describe how a star forms.

Accepted Answer

In cold, dense molecular clouds, gravity...

Question 10

Briefly summarize the stages of life for a low-mass star.

Accepted Answer

The protostar assembles from the molecul...

Question 11

Identify the correct sequence of life events for a high mass star.

Accepted Answer

A)   Main sequence, red supergiant, supernova, neutron star
B)   Main sequence, red supergiant, neutron star, supernova
C)   Red supergiant, main sequence, neutron star, supernova
D)   Red supergiant, main sequence, supernova, neutron starE) B) and D)
F) A) and C)

Question 12

Which of the following statements about degeneracy pressure is not true?

Accepted Answer

A)   Degeneracy pressure varies with the temperature of the star.
B)   Degeneracy pressure can halt gravitational contraction of a star even when no fusion is occurring in the core.
C)   Degeneracy pressure keeps any protostar less than 0.08 solar mass from becoming a true, hydrogen-fusing star.
D)   Degeneracy pressure is a consequence of the laws of quantum mechanics.E) All of the above
F) None of the above

Question 13

What happens after the helium flash?

Accepted Answer

A)   The core quickly heats up and expands.
B)   The star breaks apart in a violent explosion.
C)   The core suddenly contracts.
D)   The core stops fusing helium.
E)   The star starts to fuse helium in a shell outside the core.F) A) and B)
G) C) and D)

Question 14

What star is the most likely to have made the atoms of gold in your jewelry or your electronics?

Accepted Answer

A)   A high-mass star
B)   A white dwarf
C)   The Sun
D)   A low-mass starE) C) and D)
F) All of the above

Question 15

All stars that become supernovae will leave behind a neutron star.

Accepted Answer

A) True 
 B)False

Question 16

What does the CNO cycle and the hydrogen proton-proton cycle have in common? Choose the best answer to the question.

Accepted Answer

A)   They both are ways to fuse hydrogen nuclei to make helium.
B)   They are both nuclear reactions; the CNO cycle makes carbon, nitrogen, and oxygen, and the proton cycle makes helium.
C)   They are both cycles in star lives.
D)   They both trigger at the same temperature.E) None of the above
F) A) and B)

Question 17

Which of the following phenomena is not commonly associated with the star formation process?

Accepted Answer

A)   Intense ultraviolet radiation coming from a protostar
B)   The formation of a spinning disk of material around a protostar
C)   Powerful "jets" shooting out along the rotation axis of a protostar
D)   Strong winds of particles blowing out into space from a protostarE) A) and B)
F) B) and D)

Question 18

The most massive stars generate energy at the end of their lives by fusing iron in their cores.

Accepted Answer

A) True 
 B)False

Question 19

Which of the following properties describes a low-mass star?

Accepted Answer

A)   Has higher main-sequence luminosities than high mass stars
B)   Late in life, fuses carbon into oxygen
C)   Ends its life as a supernova
D)   Has longer lifetimes than high mass starsE) C) and D)
F) None of the above

Question 20

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)  helium core?

Accepted Answer

A)   iv
B)   iii
C)   vii
D)   vi
E)   viiiF) C) and E)
G) B) and E)

Exam 12: Star Stuff

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) helium core?

Correct AnswerverifiedShow Answer

Approximately what core temperature is required before hydrogen fusion can begin in a star?

Correct AnswerverifiedShow Answer

Most interstellar dust grains

Correct AnswerverifiedShow Answer

Which of the following statements about various stages of core nuclear burning (hydrogen, helium, carbon, and so on) in a high-mass star is not true?

Correct AnswerverifiedShow Answer

Choose from the list below for the following questions. You may use a choice more than once. -Which method of energy generation provides the source of energy for a protostar?

Correct AnswerverifiedShow Answer

Identify the correct sequence of life events for a high mass star.

Correct AnswerverifiedShow Answer

Explain how some stars form in binary systems.

Correct AnswerverifiedAs a molecular cloud contracts, it break...View AnswerShow Answer

Which of the following statements about degeneracy pressure is not true?

Correct AnswerverifiedShow Answer

All stars that become supernovae will leave behind a neutron star.

Correct AnswerverifiedShow Answer

Briefly describe how a star forms.

Correct AnswerverifiedIn cold, dense molecular clouds, gravity...View AnswerShow Answer

When does a protostar become a main-sequence star?

Correct AnswerverifiedShow Answer

Which of the following properties describes a low-mass star?

Correct AnswerverifiedShow Answer

What star is the most likely to have made the atoms of gold in your jewelry or your electronics?

Correct AnswerverifiedShow Answer

The most massive stars generate energy at the end of their lives by fusing iron in their cores.

Correct AnswerverifiedShow Answer

What happens after the helium flash?

Correct AnswerverifiedShow Answer

Although some photographs show what looks like jets of material near many young stars, we now know that these "jets" actually represent gas from the surrounding nebula that is falling onto the stars.

Correct AnswerverifiedShow Answer

Which of the following phenomena is not commonly associated with the star formation process?

Correct AnswerverifiedShow Answer

What does the CNO cycle and the hydrogen proton-proton cycle have in common? Choose the best answer to the question.

Correct AnswerverifiedShow Answer

Choose from the list below for the following questions. You may use a choice more than once. -Which method of energy generation is used by the Sun today?

Correct AnswerverifiedShow Answer

Briefly summarize the stages of life for a low-mass star.

Correct AnswerverifiedThe protostar assembles from the molecul...View AnswerShow Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
As a molecular cloud contracts, it break...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
In cold, dense molecular clouds, gravity...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
The protostar assembles from the molecul...
View Answer