Question 1

What is the CNO cycle?

Accepted Answer

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

Question 2

Our Sun is considered to be a(n)_ .

Accepted Answer

A) intermediate- mass star 
B) brown dwarf 
C) low- mass star 
D) high- mass star 
A) intermediate- mass star 
B) brown dwarf 
C) low- mass star 
D) high- mass star C

Question 3

Consider the star to which the arrow points. Which of the following statements about this star is not true?

Accepted Answer

A) Its core temperature is higher than the Sun's. 
B) It is larger in radius than the Sun. 
C) Its surface temperature is lower than the Sun's. 
D) It is significantly less massive than the Sun. 
E) It is brighter than the Sun. 
A) Its core temperature is higher than the Sun's. 
B) It is larger in radius than the Sun. 
C) Its surface temperature is lower than the Sun's. 
D) It is significantly less massive than the Sun. 
E) It is brighter than the Sun. D

Question 4

Which event marks the beginning of a supernova?

Accepted Answer

A) the sudden collapse of an iron core into a compact ball of neutrons 
B) the sudden initiation of the CNO cycle 
C) the onset of helium burning after a helium flash 
D) the beginning of neon burning in an extremely massive star 
A) the sudden collapse of an iron core into a compact ball of neutrons 
B) the sudden initiation of the CNO cycle 
C) the onset of helium burning after a helium flash 
D) the beginning of neon burning in an extremely massive star

Question 5

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

Accepted Answer

The first stages are similar to those of

Question 6

Why do flat disks form around young stars?

Accepted Answer

A) They don't; the stars form from the disks. 
B) Centrifugal force pushes gas outward from the spinning gas cloud. 
C) Intense winds from nearby massive stars flatten the gas cloud. 
D) Collisions between rotating gas particles flatten the gas cloud along the axis of rotation. 
A) They don't; the stars form from the disks. 
B) Centrifugal force pushes gas outward from the spinning gas cloud. 
C) Intense winds from nearby massive stars flatten the gas cloud. 
D) Collisions between rotating gas particles flatten the gas cloud along the axis of rotation.

Question 7

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

Accepted Answer

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

Question 8

The birth place of stars: Discuss the observational evidence that supports the idea that most stars are formed in groups from large clouds of interstellar gas and dust.

Accepted Answer

The youngest stars (with ages determined

Question 9

The interstellar clouds called molecular clouds are .

Accepted Answer

A) the cool clouds in which stars form 
B) the hot clouds of gas expelled by dying stars 
C) the clouds in which elements such as carbon, nitrogen, and oxygen are made 
D) clouds that are made mostly of complex molecules such as carbon dioxide and sulfur dioxide 
A) the cool clouds in which stars form 
B) the hot clouds of gas expelled by dying stars 
C) the clouds in which elements such as carbon, nitrogen, and oxygen are made 
D) clouds that are made mostly of complex molecules such as carbon dioxide and sulfur dioxide

Question 10

Angular momentum plays an important role in star formation. Which of the following characteristics of a protostellar system is probably not strongly affected by the star's angular momentum?

Accepted Answer

A) the formation of a protostellar disk 
B) the existence of protostellar jets 
C) the onset of core hydrogen fusion 
D) the strength of protostellar winds 
A) the formation of a protostellar disk 
B) the existence of protostellar jets 
C) the onset of core hydrogen fusion 
D) the strength of protostellar winds

Question 11

What is the CNO cycle?

Accepted Answer

A) the set of fusion reactions that have produced all the carbon, nitrogen, and oxygen in the universe 
B) the process by which helium is fused into carbon, nitrogen, and oxygen 
C) the process by which carbon is fused into nitrogen and oxygen 
D) a set of steps by which four hydrogen nuclei fuse into one helium nucleus 
A) the set of fusion reactions that have produced all the carbon, nitrogen, and oxygen in the universe 
B) the process by which helium is fused into carbon, nitrogen, and oxygen 
C) the process by which carbon is fused into nitrogen and oxygen 
D) a set of steps by which four hydrogen nuclei fuse into one helium nucleus

Question 12

What eventually halts the gravitational collapse of an interstellar gas cloud that forms an object that is massive enough to become a star?

Accepted Answer

A) the central object becoming hot enough to sustain nuclear fusion in its core 
B) nothing; all collapsing gas clouds become black holes 
C) a critical fraction of the gas has been driven further into space 
D) the crowding of electrons in the core 
A) the central object becoming hot enough to sustain nuclear fusion in its core 
B) nothing; all collapsing gas clouds become black holes 
C) a critical fraction of the gas has been driven further into space 
D) the crowding of electrons in the core

Question 13

According to this plot, which is the third most abundant element in the universe?

Accepted Answer

A) helium 
B) oxygen 
C) hydrogen 
D) boron 
E) lithium 
A) helium 
B) oxygen 
C) hydrogen 
D) boron 
E) lithium

Question 14

Why are elements with even numbers of protons more abundant, on average, than elements with odd numbers of protons?

Accepted Answer

A) because elements are mainly made in fusion reactions with helium nuclei 
B) because elements are mainly made in fusion reactions with hydrogen nuclei 
C) because when elements split in a fission reaction, they prefer to split with all the protons paired 
D) There's no explanation; it's something of a mystery to be explained or it may be a coincidence. 
A) because elements are mainly made in fusion reactions with helium nuclei 
B) because elements are mainly made in fusion reactions with hydrogen nuclei 
C) because when elements split in a fission reaction, they prefer to split with all the protons paired 
D) There's no explanation; it's something of a mystery to be explained or it may be a coincidence.

Question 15

Falsifying Scientific Theories: In many simple expositions of the scientific method, it is often stated that if a scientific theory makes an incorrect prediction, it is falsified and must be discarded. Argue against this simple view of the scientific method by using the Algol paradox (Section 13.4)as a case study. In particular, why did astronomers not discard the theory of stellar evolution despite an apparent direct contradiction of a fundamental prediction of stellar evolution, that more massive stars evolve faster than less massive stars?

Accepted Answer

The simple view of the scientific method

Question 16

What can we learn about a star from a life track on an H- R diagram?

Accepted Answer

A) when it will die 
B) what surface temperature and luminosity it will have at each stage of its life 
C) how long ago it was born 
D) where it is located 
E) all of the above 
A) when it will die 
B) what surface temperature and luminosity it will have at each stage of its life 
C) how long ago it was born 
D) where it is located 
E) all of the above

Question 17

What will happen in the Sun immediately after it has exhausted its supply of hydrogen in its core?

Accepted Answer

A) The helium core will shrink, heat, and start fusing helium to carbon. 
B) The core will collapse and a supernova will result. 
C) The Sun will turn into a white dwarf and cool off forever. 
D) The helium core will shrink and heat; a shell of hydrogen will start fusing. 
A) The helium core will shrink, heat, and start fusing helium to carbon. 
B) The core will collapse and a supernova will result. 
C) The Sun will turn into a white dwarf and cool off forever. 
D) The helium core will shrink and heat; a shell of hydrogen will start fusing.

Question 18

Which type of star spends the shortest time as a main sequence star?

Accepted Answer

A) B star 
B) G star 
C) O star 
D) M star 
A) B star 
B) G star 
C) O star 
D) M star

Question 19

Which two processes can generate energy to help a star maintain its internal thermal pressure?

Accepted Answer

A) nuclear fusion and gravitational contraction 
B) nuclear fission and supernova 
C) nuclear fusion and supernova 
D) nuclear fusion and nuclear fission 
A) nuclear fusion and gravitational contraction 
B) nuclear fission and supernova 
C) nuclear fusion and supernova 
D) nuclear fusion and nuclear fission

Question 20

Which of the following masses separates low mass stars from high mass stars?

Accepted Answer

A) about 0.08 solar masses 
B) about 1 solar mass 
C) about 2 solar masses 
D) about 50 solar masses 
E) about 150 solar masses 
A) about 0.08 solar masses 
B) about 1 solar mass 
C) about 2 solar masses 
D) about 50 solar masses 
E) about 150 solar masses

What is the CNO cycle?

Our Sun is considered to be a(n)_ .

Consider the star to which the arrow points. Which of the following statements about this star is not true?

Which event marks the beginning of a supernova?

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

Why do flat disks form around young stars?

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

The birth place of stars: Discuss the observational evidence that supports the idea that most stars are formed in groups from large clouds of interstellar gas and dust.

The interstellar clouds called molecular clouds are .

Angular momentum plays an important role in star formation. Which of the following characteristics of a protostellar system is probably not strongly affected by the star's angular momentum?

What is the CNO cycle?

What eventually halts the gravitational collapse of an interstellar gas cloud that forms an object that is massive enough to become a star?

According to this plot, which is the third most abundant element in the universe?

Why are elements with even numbers of protons more abundant, on average, than elements with odd numbers of protons?

What can we learn about a star from a life track on an H- R diagram?

What will happen in the Sun immediately after it has exhausted its supply of hydrogen in its core?

Which type of star spends the shortest time as a main sequence star?

Which two processes can generate energy to help a star maintain its internal thermal pressure?

Which of the following masses separates low mass stars from high mass stars?

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: the Cosmic Messenger

Formation of the Solar System

Earth and the Terrestrial Worlds

Jovian Planet System

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

Other Planetary Systems: the New Science of Distant Worlds

Our Star

Surveying the Stars

The Bizarre Stellar Graveyard

Our Galaxy

A Universe of Galaxies

The Birth of the Universe

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

Life in the Universe

Filters

Exam 13: Star Stuff

What is the CNO cycle?

Our Sun is considered to be a(n)_ .

Consider the star to which the arrow points. Which of the following statements about this star is not true?

Which event marks the beginning of a supernova?

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

Why do flat disks form around young stars?

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

The birth place of stars: Discuss the observational evidence that supports the idea that most stars are formed in groups from large clouds of interstellar gas and dust.

The interstellar clouds called molecular clouds are .

Angular momentum plays an important role in star formation. Which of the following characteristics of a protostellar system is probably not strongly affected by the star's angular momentum?

What is the CNO cycle?

What eventually halts the gravitational collapse of an interstellar gas cloud that forms an object that is massive enough to become a star?

According to this plot, which is the third most abundant element in the universe?

Why are elements with even numbers of protons more abundant, on average, than elements with odd numbers of protons?

What can we learn about a star from a life track on an H- R diagram?

What will happen in the Sun immediately after it has exhausted its supply of hydrogen in its core?

Which type of star spends the shortest time as a main sequence star?

Which two processes can generate energy to help a star maintain its internal thermal pressure?

Which of the following masses separates low mass stars from high mass stars?

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: the Cosmic Messenger

Formation of the Solar System

Earth and the Terrestrial Worlds

Jovian Planet System

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

Other Planetary Systems: the New Science of Distant Worlds

Our Star

Surveying the Stars

The Bizarre Stellar Graveyard

Our Galaxy

A Universe of Galaxies

The Birth of the Universe

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

Life in the Universe

Filters