Question 1

A planetary nebula is

Accepted Answer

A)  a shell of ejected gases. 
B)  the formation stages of planets around stars. 
C)  a gas cloud surrounding a planet after its formation. 
D)  the spherical cloud of gas produced by a supernova explosion. 
A)  a shell of ejected gases. 
B)  the formation stages of planets around stars. 
C)  a gas cloud surrounding a planet after its formation. 
D)  the spherical cloud of gas produced by a supernova explosion.

Question 2

What important event was recorded by ancient Chinese astronomers in A.D. 1054?

Accepted Answer

A)  brilliant worldwide auroral display 
B)  appearance of a nearby nova explosion in the Milky Way Galaxy 
C)  bright binary star undergoing eclipse 
D)  appearance of a supernova in the Crab Nebula 
A)  brilliant worldwide auroral display 
B)  appearance of a nearby nova explosion in the Milky Way Galaxy 
C)  bright binary star undergoing eclipse 
D)  appearance of a supernova in the Crab Nebula

Question 3

The magnetic fields of planets demonstrate that rotation is a requirement for an object to produce a magnetic field. It is not surprising, then, that when a massive star collapses the rotation rate

Accepted Answer

A)  and the magnetic field strength both increase. 
B)  increases but the magnetic field strength decreases. 
C)  decreases but the magnetic field strength increases. 
D)  and the magnetic field strength both decrease. 
A)  and the magnetic field strength both increase. 
B)  increases but the magnetic field strength decreases. 
C)  decreases but the magnetic field strength increases. 
D)  and the magnetic field strength both decrease.

Question 4

Why do astronomers believe a magnetar can have a much stronger magnetic field than that of an ordinary neutron star?

Accepted Answer

A)  Magnetars were formed from supergiant stars many times larger than the stars that produced ordinary neutron stars. 
B)  When first formed as neutron stars, magnetars were spinning rapidly enough that the magnetic fields produced by convection amplified the magnetic field of the original star. 
C)  Magnetars are superconducting throughout. 
D)  Magnetars have a higher proportion of protons and thus have stronger electric currents. 
A)  Magnetars were formed from supergiant stars many times larger than the stars that produced ordinary neutron stars. 
B)  When first formed as neutron stars, magnetars were spinning rapidly enough that the magnetic fields produced by convection amplified the magnetic field of the original star. 
C)  Magnetars are superconducting throughout. 
D)  Magnetars have a higher proportion of protons and thus have stronger electric currents.

Question 5

What will be the mass of the Sun at the end of its asymptotic giant branch (AGB) phase, due to mass loss to space by its stellar wind?

Accepted Answer

A)  still almost 1 solar mass since mass loss is negligible for a low-mass star like the Sun 
B)  between 0.1 and 0.2 solar mass 
C)  about 0.8 solar mass 
D)  about 0.5 solar mass 
A)  still almost 1 solar mass since mass loss is negligible for a low-mass star like the Sun 
B)  between 0.1 and 0.2 solar mass 
C)  about 0.8 solar mass 
D)  about 0.5 solar mass

Question 6

Supernovae have been detected

Accepted Answer

A)  in both the Milky Way Galaxy and other galaxies. 
B)  only at X-ray wavelengths. 
C)  only in elliptical galaxies, never in spirals. 
D)  only in the Milky Way Galaxy. 
A)  in both the Milky Way Galaxy and other galaxies. 
B)  only at X-ray wavelengths. 
C)  only in elliptical galaxies, never in spirals. 
D)  only in the Milky Way Galaxy.

Question 7

The interior of a neutron star is believed to contain

Accepted Answer

A)  neutrons compressed into a crystalline lattice structure by very high pressure. 
B)  a dense gas consisting mostly of neutrons. 
C)  a metallic fluid of almost pure iron. 
D)  neutrons in a superfluid state. 
A)  neutrons compressed into a crystalline lattice structure by very high pressure. 
B)  a dense gas consisting mostly of neutrons. 
C)  a metallic fluid of almost pure iron. 
D)  neutrons in a superfluid state.

Question 8

What is the origin of the rings of gas that surround SN 1987A?

Accepted Answer

A)  The rings were formed by stellar winds before the supernova erupted. 
B)  These were caused by the gamma rays, which also caused photodisintegration. 
C)  These rings were pushed out by the core bounce. 
D)  The rings were formed when the shock wave lifted the outer layers of the star. 
A)  The rings were formed by stellar winds before the supernova erupted. 
B)  These were caused by the gamma rays, which also caused photodisintegration. 
C)  These rings were pushed out by the core bounce. 
D)  The rings were formed when the shock wave lifted the outer layers of the star.

Question 9

Which force induces the core to contract inward and get hotter in massive stars at the conclusion of each episode of nuclear fusion, such as the carbon-, oxygen-, and silicon- fusion cycles?

Accepted Answer

A)  gravity 
B)  gas pressure produced by the very high gas temperatures 
C)  electron degeneracy pressure 
D)  nuclear attractive force between nuclei and between neutrons and protons 
A)  gravity 
B)  gas pressure produced by the very high gas temperatures 
C)  electron degeneracy pressure 
D)  nuclear attractive force between nuclei and between neutrons and protons

Question 10

Electron degeneracy occurs when the carbon core of a white dwarf becomes dense enough. Neutron degeneracy occurs when a neutron star becomes dense enough. Why is there no "proton degeneracy" in some density range between electron and neutron degeneracy?

Accepted Answer

A)  These degeneracies can occur only for neutral particles, and protons carry an electric charge. 
B)  The pressure at which the electron degeneracy is overcome (so that the core collapses) is also sufficient to combine electrons and protons to form neutrons. Thus, most protons disappear when the electron degeneracy ends. 
C)  Protons are too large and heavy to exert degeneracy pressure. This concept applies only to smaller, lighter particles like electrons. 
D)  Protons are not governed by the Pauli exclusion principle, as are electrons and neutrons. 
A)  These degeneracies can occur only for neutral particles, and protons carry an electric charge. 
B)  The pressure at which the electron degeneracy is overcome (so that the core collapses) is also sufficient to combine electrons and protons to form neutrons. Thus, most protons disappear when the electron degeneracy ends. 
C)  Protons are too large and heavy to exert degeneracy pressure. This concept applies only to smaller, lighter particles like electrons. 
D)  Protons are not governed by the Pauli exclusion principle, as are electrons and neutrons.

Question 11

The core collapse phase at the end of the life of a massive star is triggered when

Accepted Answer

A)  the helium flash and thermal pulses have expelled the star's envelope. 
B)  the density reaches the threshold for electron degeneracy pressure to become important. 
C)  nuclear fusion has produced a significant amount of iron in its core. 
D)  the core becomes as dense as an atomic nucleus. 
A)  the helium flash and thermal pulses have expelled the star's envelope. 
B)  the density reaches the threshold for electron degeneracy pressure to become important. 
C)  nuclear fusion has produced a significant amount of iron in its core. 
D)  the core becomes as dense as an atomic nucleus.

Question 12

Which of these astronomical objects is MOST closely associated with a pulsar?

Accepted Answer

A)  red giant star 
B)  neutron star 
C)  black hole 
D)  white dwarf star 
A)  red giant star 
B)  neutron star 
C)  black hole 
D)  white dwarf star

Question 13

A white dwarf star is supported from collapse under gravity by

Accepted Answer

A)  pressure of the gas heated by nuclear fusion reactions in its core. 
B)  centrifugal force due to rapid rotation. 
C)  degenerate-electron pressure in the compact interior. 
D)  pressure of the gas heated by nuclear fusion reactions in a shell around its core. 
A)  pressure of the gas heated by nuclear fusion reactions in its core. 
B)  centrifugal force due to rapid rotation. 
C)  degenerate-electron pressure in the compact interior. 
D)  pressure of the gas heated by nuclear fusion reactions in a shell around its core.

Question 14

Which one of these phenomena is NOT associated with a rotating neutron star?

Accepted Answer

A)  magnetar 
B)  soft gamma-ray repeater 
C)  rotating radio transient 
D)  weakly interacting massive particles 
A)  magnetar 
B)  soft gamma-ray repeater 
C)  rotating radio transient 
D)  weakly interacting massive particles

Question 15

The sequence of thermonuclear fusion processes inside massive stars can transform elements such as carbon and oxygen into heavier elements and generate excess energy until iron has been produced. Why is it NOT possible for fusion reactions to release energy from iron nuclei?

Accepted Answer

A)  The electrostatic charge of iron nuclei is so great that other nuclei cannot approach closely enough to react with them. 
B)  Iron has the largest nucleus of all elements, and fusing other nuclei with iron actually reduces the size of the nucleus. 
C)  Iron is the heaviest naturally occurring element. 
D)  The protons and neutrons in an iron nucleus are so tightly bound together that fusing other nuclei with iron absorbs energy rather than releases it. 
A)  The electrostatic charge of iron nuclei is so great that other nuclei cannot approach closely enough to react with them. 
B)  Iron has the largest nucleus of all elements, and fusing other nuclei with iron actually reduces the size of the nucleus. 
C)  Iron is the heaviest naturally occurring element. 
D)  The protons and neutrons in an iron nucleus are so tightly bound together that fusing other nuclei with iron absorbs energy rather than releases it.

Question 16

How did SN 1987A differ from most other observed supernovae?

Accepted Answer

A)  SN 1987A occurred in an external galaxy, not the Milky Way Galaxy. 
B)  SN 1987A reached a maximum luminosity several times that of a normal supernova, because it exploded as a red supergiant. 
C)  SN 1987A declined in brightness much faster than most supernovae. 
D)  SN 1987A reached a maximum luminosity much later than a normal supernova, because it exploded as a blue supergiant. 
A)  SN 1987A occurred in an external galaxy, not the Milky Way Galaxy. 
B)  SN 1987A reached a maximum luminosity several times that of a normal supernova, because it exploded as a red supergiant. 
C)  SN 1987A declined in brightness much faster than most supernovae. 
D)  SN 1987A reached a maximum luminosity much later than a normal supernova, because it exploded as a blue supergiant.

Question 17

What happens to the outer layers of a low-mass star after the helium core and shell fusion stages are completed?

Accepted Answer

A)  The star stabilizes at the size of a red giant star, radiation pressure from below balancing gravity from the core, and slowly cools for the rest of its life. 
B)  The outer layers are spun off into space to make a spiral structure known as a spiral galaxy. 
C)  The outer layers are propelled slowly away from the core to form a planetary nebula. 
D)  The star contracts back onto the core and becomes hot enough to undergo further hydrogen fusion, leading to a very hot and active, white dwarf star. 
A)  The star stabilizes at the size of a red giant star, radiation pressure from below balancing gravity from the core, and slowly cools for the rest of its life. 
B)  The outer layers are spun off into space to make a spiral structure known as a spiral galaxy. 
C)  The outer layers are propelled slowly away from the core to form a planetary nebula. 
D)  The star contracts back onto the core and becomes hot enough to undergo further hydrogen fusion, leading to a very hot and active, white dwarf star.

Question 18

Near the end of its life a high-mass star has six active fusion shells surrounding its core. How many such shells did it have when it was on the main sequence?

Accepted Answer

A)  none 
B)  one 
C)  three 
D)  six 
A)  none 
B)  one 
C)  three 
D)  six

Question 19

The end states of low-mass stars differ dramatically from high-mass stars. In this context, what is the boundary between these two classifications?

Accepted Answer

A)  0.4 MSun 
B)  2.0 MSun 
C)  8.0 MSun 
D)  16.0 MSun 
A)  0.4 MSun 
B)  2.0 MSun 
C)  8.0 MSun 
D)  16.0 MSun

Question 20

Which of these is a method astronomers have recently used to study the structure of white dwarfs?

Accepted Answer

A)  measuring how their light curves vary with time to study pulsations of the stars 
B)  measuring gravitational waves generated by pulsations of the stars 
C)  measuring neutrinos released when a cool white dwarf crystallizes 
D)  capturing material ejected by novae with spacecraft 
A)  measuring how their light curves vary with time to study pulsations of the stars 
B)  measuring gravitational waves generated by pulsations of the stars 
C)  measuring neutrinos released when a cool white dwarf crystallizes 
D)  capturing material ejected by novae with spacecraft

A planetary nebula is

What important event was recorded by ancient Chinese astronomers in A.D. 1054?

The magnetic fields of planets demonstrate that rotation is a requirement for an object to produce a magnetic field. It is not surprising, then, that when a massive star collapses the rotation rate

Why do astronomers believe a magnetar can have a much stronger magnetic field than that of an ordinary neutron star?

What will be the mass of the Sun at the end of its asymptotic giant branch (AGB) phase, due to mass loss to space by its stellar wind?

Supernovae have been detected

The interior of a neutron star is believed to contain

What is the origin of the rings of gas that surround SN 1987A?

Which force induces the core to contract inward and get hotter in massive stars at the conclusion of each episode of nuclear fusion, such as the carbon-, oxygen-, and silicon- fusion cycles?

Electron degeneracy occurs when the carbon core of a white dwarf becomes dense enough. Neutron degeneracy occurs when a neutron star becomes dense enough. Why is there no "proton degeneracy" in some density range between electron and neutron degeneracy?

The core collapse phase at the end of the life of a massive star is triggered when

Which of these astronomical objects is MOST closely associated with a pulsar?

A white dwarf star is supported from collapse under gravity by

Which one of these phenomena is NOT associated with a rotating neutron star?

The sequence of thermonuclear fusion processes inside massive stars can transform elements such as carbon and oxygen into heavier elements and generate excess energy until iron has been produced. Why is it NOT possible for fusion reactions to release energy from iron nuclei?

How did SN 1987A differ from most other observed supernovae?

What happens to the outer layers of a low-mass star after the helium core and shell fusion stages are completed?

Near the end of its life a high-mass star has six active fusion shells surrounding its core. How many such shells did it have when it was on the main sequence?

The end states of low-mass stars differ dramatically from high-mass stars. In this context, what is the boundary between these two classifications?

Which of these is a method astronomers have recently used to study the structure of white dwarfs?

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Atomic Physics and Spectra

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

Characterizing Stars

The Lives of Stars From Birth Through Middle Age

Black Holes: Matters of Gravity

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Cosmology

Astrobiology

Filters

Exam 14: The Death of Stars

A planetary nebula is

What important event was recorded by ancient Chinese astronomers in A.D. 1054?

The magnetic fields of planets demonstrate that rotation is a requirement for an object to produce a magnetic field. It is not surprising, then, that when a massive star collapses the rotation rate

Why do astronomers believe a magnetar can have a much stronger magnetic field than that of an ordinary neutron star?

What will be the mass of the Sun at the end of its asymptotic giant branch (AGB) phase, due to mass loss to space by its stellar wind?

Supernovae have been detected

The interior of a neutron star is believed to contain

What is the origin of the rings of gas that surround SN 1987A?

Which force induces the core to contract inward and get hotter in massive stars at the conclusion of each episode of nuclear fusion, such as the carbon-, oxygen-, and silicon- fusion cycles?

Electron degeneracy occurs when the carbon core of a white dwarf becomes dense enough. Neutron degeneracy occurs when a neutron star becomes dense enough. Why is there no "proton degeneracy" in some density range between electron and neutron degeneracy?

The core collapse phase at the end of the life of a massive star is triggered when

Which of these astronomical objects is MOST closely associated with a pulsar?

A white dwarf star is supported from collapse under gravity by

Which one of these phenomena is NOT associated with a rotating neutron star?

The sequence of thermonuclear fusion processes inside massive stars can transform elements such as carbon and oxygen into heavier elements and generate excess energy until iron has been produced. Why is it NOT possible for fusion reactions to release energy from iron nuclei?

How did SN 1987A differ from most other observed supernovae?

What happens to the outer layers of a low-mass star after the helium core and shell fusion stages are completed?

Near the end of its life a high-mass star has six active fusion shells surrounding its core. How many such shells did it have when it was on the main sequence?

The end states of low-mass stars differ dramatically from high-mass stars. In this context, what is the boundary between these two classifications?

Which of these is a method astronomers have recently used to study the structure of white dwarfs?

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Atomic Physics and Spectra

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

Characterizing Stars

The Lives of Stars From Birth Through Middle Age

Black Holes: Matters of Gravity

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Cosmology

Astrobiology

Filters