Question 1

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

Accepted Answer

A) As each stage ends,the core shrinks and heats further. 
B) Each successive stage creates an element with a higher atomic number and atomic mass number. 
C) As each stage ends,the reactions that occurred in previous stages continue in shells around the core. 
D) Each successive stage lasts for approximately the same amount of time. 
A) As each stage ends,the core shrinks and heats further. 
B) Each successive stage creates an element with a higher atomic number and atomic mass number. 
C) As each stage ends,the reactions that occurred in previous stages continue in shells around the core. 
D) Each successive stage lasts for approximately the same amount of time.

Question 2

What happens when the gravity of a massive star is able to overcome neutron degeneracy pressure?

Accepted Answer

A) The core contracts and becomes a white dwarf. 
B) The core contracts and becomes a ball of neutrons. 
C) The core contracts and becomes a black hole. 
D) The star explodes violently,leaving nothing behind. 
E) Gravity is not able to overcome neutron degeneracy pressure. 
A) The core contracts and becomes a white dwarf. 
B) The core contracts and becomes a ball of neutrons. 
C) The core contracts and becomes a black hole. 
D) The star explodes violently,leaving nothing behind. 
E) Gravity is not able to overcome neutron degeneracy pressure.

Question 3

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

Question 4

There is no limit to the mass with which a star can be born.

Accepted Answer

A) True 
 B)False

Question 5

You discover a binary star system in which one member is a15MSᵤn main-sequence star and the other star is a 10MSᵤn giant.How do we believe 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 transferred some of its mass to its companion. 
B) Despite the low odds of finding a system with two such massive stars,there is nothing surprising about the fact that such systems exist. 
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 main-sequence star probably is a pulsating variable star and therefore appears to be less massive than it really is. 
E) 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 star millions of years later than its less massive companion. 
A) The giant must once have been the more massive star but transferred some of its mass to its companion. 
B) Despite the low odds of finding a system with two such massive stars,there is nothing surprising about the fact that such systems exist. 
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 main-sequence star probably is a pulsating variable star and therefore appears to be less massive than it really is. 
E) 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 star millions of years later than its less massive companion.

Question 6

Why do scientists think that our solar system must have formed sometime after nearby supernovae explosions?

Accepted Answer

A) existence of heavy elements 
B) solar temperature too low 
C) our Sun is a G-type star 
D) They don't-scientists believe our Sun is among the first generation of stars. 
A) existence of heavy elements 
B) solar temperature too low 
C) our Sun is a G-type star 
D) They don't-scientists believe our Sun is among the first generation of stars.

Question 7

Which low-mass star does not have fusion occurring in its central core?

Accepted Answer

A) a main-sequence star 
B) a red giant 
C) a helium-burning star 
A) a main-sequence star 
B) a red giant 
C) a helium-burning star

Question 8

Tidal forces are very important to the Algol system today,but were not important when both stars were still on the main sequence.Why not?

Accepted Answer

A) Main-sequence stars in a system like the Algol system are small compared to their physical separation. 
B) Main-sequence stars are too big to be affected by tidal forces. 
C) Main-sequence stars are too massive to be affected by tidal forces. 
D) Main-sequence stars are unaffected by tidally-induced mass transfer. 
A) Main-sequence stars in a system like the Algol system are small compared to their physical separation. 
B) Main-sequence stars are too big to be affected by tidal forces. 
C) Main-sequence stars are too massive to be affected by tidal forces. 
D) Main-sequence stars are unaffected by tidally-induced mass transfer.

Question 9

What is the CNO cycle?

Accepted Answer

A) the process by which helium is fused into carbon,nitrogen,and oxygen 
B) the process by which carbon is fused into nitrogen and oxygen 
C) a type of hydrogen fusion that uses carbon,nitrogen,and oxygen atoms as catalysts 
D) the period of a massive star's life when carbon,nitrogen,and oxygen are fusing in different shells outside the core 
E) the period of a low-mass star's life when it can no longer fuse carbon,nitrogen,and oxygen in its core 
A) the process by which helium is fused into carbon,nitrogen,and oxygen 
B) the process by which carbon is fused into nitrogen and oxygen 
C) a type of hydrogen fusion that uses carbon,nitrogen,and oxygen atoms as catalysts 
D) the period of a massive star's life when carbon,nitrogen,and oxygen are fusing in different shells outside the core 
E) the period of a low-mass star's life when it can no longer fuse carbon,nitrogen,and oxygen in its core

Question 10

At approximately what temperature can helium fusion occur?

Accepted Answer

A) 100,000 K 
B) 1 million K 
C) a few million K 
D) 100 million K 
E) 100 billion K 
A) 100,000 K 
B) 1 million K 
C) a few million K 
D) 100 million K 
E) 100 billion K

Question 11

Carbon fusion occur in high-mass stars but not in low-mass stars because

Accepted Answer

A) the cores of low-mass stars never contain significant amounts of carbon. 
B) the cores of low-mass stars never get hot enough for carbon fusion. 
C) only high-mass stars do fusion by the CNO cycle. 
D) carbon fusion can occur only in the stars known as carbon stars. 
A) the cores of low-mass stars never contain significant amounts of carbon. 
B) the cores of low-mass stars never get hot enough for carbon fusion. 
C) only high-mass stars do fusion by the CNO cycle. 
D) carbon fusion can occur only in the stars known as carbon stars.

Question 12

Compared to the star it evolved from,a red giant 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. 
A) hotter and brighter. 
B) hotter and dimmer. 
C) cooler and brighter. 
D) cooler and dimmer. 
E) the same temperature and brightness.

Question 13

Suppose that hydrogen,rather than iron,had the lowest mass per nuclear particle.Which of the following would be true?

Accepted Answer

A) Stars would be brighter. 
B) Stars would be less massive. 
C) All stars would be red giants. 
D) Nuclear fusion could not power stars. 
A) Stars would be brighter. 
B) Stars would be less massive. 
C) All stars would be red giants. 
D) Nuclear fusion could not power stars.

Question 14

What happens after a 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. 
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.

Question 15

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 dwarf 
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 dwarf

Question 16

What happens to the core of a star after a planetary nebula occurs?

Accepted Answer

A) It contracts from a protostar to a main-sequence star. 
B) It breaks apart in a violent explosion. 
C) It becomes a white dwarf. 
D) It becomes a neutron star. 
E) none of the above 
A) It contracts from a protostar to a main-sequence star. 
B) It breaks apart in a violent explosion. 
C) It becomes a white dwarf. 
D) It becomes a neutron star. 
E) none of the above

Question 17

The heaviest element produced by stars or in supernovae is silicon.

Accepted Answer

A) True 
 B)False

Question 18

Which of the following stars will live longest?

Accepted Answer

A) a 1-solar-mass star 
B) a 2-solar-mass star 
C) a 3-solar-mass star 
D) a 4-solar-mass star 
E) a 5-solar-mass star 
A) a 1-solar-mass star 
B) a 2-solar-mass star 
C) a 3-solar-mass star 
D) a 4-solar-mass star 
E) a 5-solar-mass star

Question 19

Which of the following statements about stages of nuclear burning (i.e. ,first-stage hydrogen burning,second-stage helium burning,etc. )in a massive star is not true?

Accepted Answer

A) Each successive stage of fusion requires higher temperatures than the previous stages. 
B) As each stage ends,the core shrinks further. 
C) Each successive stage creates an element with a higher atomic weight. 
D) Each successive stage lasts for approximately the same amount of time. 
A) Each successive stage of fusion requires higher temperatures than the previous stages. 
B) As each stage ends,the core shrinks further. 
C) Each successive stage creates an element with a higher atomic weight. 
D) Each successive stage lasts for approximately the same amount of time.

Question 20

What are the three types of pressure that can push against the inward force of gravity? Explain what causes each pressure and where it would be likely to occur.

Accepted Answer

(1)Thermal pressure occurs when the part

Exam 17: Star Stuff

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

What happens when the gravity of a massive star is able to overcome neutron degeneracy pressure?

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?

There is no limit to the mass with which a star can be born.

You discover a binary star system in which one member is a15MSᵤn main-sequence star and the other star is a 10MSᵤn giant.How do we believe that a star system such as this might have come to exist?

Why do scientists think that our solar system must have formed sometime after nearby supernovae explosions?

Which low-mass star does not have fusion occurring in its central core?

Tidal forces are very important to the Algol system today,but were not important when both stars were still on the main sequence.Why not?

What is the CNO cycle?

At approximately what temperature can helium fusion occur?

Carbon fusion occur in high-mass stars but not in low-mass stars because

Compared to the star it evolved from,a red giant is

Suppose that hydrogen,rather than iron,had the lowest mass per nuclear particle.Which of the following would be true?

What happens after a helium flash?

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

What happens to the core of a star after a planetary nebula occurs?

The heaviest element produced by stars or in supernovae is silicon.

Which of the following stars will live longest?

Which of the following statements about stages of nuclear burning (i.e. ,first-stage hydrogen burning,second-stage helium burning,etc. )in a massive star is not true?

What are the three types of pressure that can push against the inward force of gravity? Explain what causes each pressure and where it would be likely to occur.

A Modern View of the Universe

Discovering the Universe for Yourself

The Science of Astronomy

Making Sense of the Universe: Understanding Motion, Energy, and Gravity

Light and Matter: Reading Messages from the Cosmos

Telescopes: Portals of Discovery

Our Planetary System

Formation of the Solar System

Planetary Geology: Earth and the Other Terrestrial Worlds

Planetary Atmospheres: Earth and the Other Terrestrial Worlds

Jovian Planet Systems

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Other Planetary Systems: The New Science of Distant Worlds

Our Star

Surveying the Stars

Star Birth

The Bizarre Stellar Graveyard

Our Galaxy

Galaxies and the Foundations of Modern Cosmology

Galaxy Evolution

The Birth of the Universe

Dark Matter, Dark Energy, and the Fate of the Universe

Life in the Universe

Celestial Timekeeping and Navigation

Space and Time

Spacetime and Gravity

Building Blocks of the Universe

Filters