Question 1

The interiors of white dwarf stars are characteristically

Accepted Answer

A)  mainly carbon and oxygen nuclei supported by electron degeneracy pressure in a volume about the size of the Sun. 
B)  mostly hydrogen nuclei supported by normal gas pressure due to the very high gas temperature, in a volume about the size of Earth. 
C)  mainly carbon and oxygen nuclei supported by electron degeneracy pressure in a volume about the size of Earth. 
D)  mainly helium nuclei supported by electron degeneracy pressure in a volume with a radius about 11 times that of Earth, about the volume of Jupiter. 
A)  mainly carbon and oxygen nuclei supported by electron degeneracy pressure in a volume about the size of the Sun. 
B)  mostly hydrogen nuclei supported by normal gas pressure due to the very high gas temperature, in a volume about the size of Earth. 
C)  mainly carbon and oxygen nuclei supported by electron degeneracy pressure in a volume about the size of Earth. 
D)  mainly helium nuclei supported by electron degeneracy pressure in a volume with a radius about 11 times that of Earth, about the volume of Jupiter.

Question 2

In what manner does an isolated white dwarf generate energy?

Accepted Answer

A)  hydrogen fusion 
B)  helium fusion 
C)  gravitational contraction 
D)  An isolated white dwarf does not generate energy. 
A)  hydrogen fusion 
B)  helium fusion 
C)  gravitational contraction 
D)  An isolated white dwarf does not generate energy.

Question 3

The light from the most recent supernova that was visible to the unaided eye arrived at Earth in

Accepted Answer

A)  A.D. 1604. 
B)  A.D. 1054. 
C)  A.D. 1987. 
D)  A.D. 1572. 
A)  A.D. 1604. 
B)  A.D. 1054. 
C)  A.D. 1987. 
D)  A.D. 1572.

Question 4

Fast radio bursts originate from

Accepted Answer

A)  Type Ia supernovae. 
B)  Type II supernovae 
C)  supermassive black holes. 
D)  sources outside the Galaxy that are otherwise unknown. 
A)  Type Ia supernovae. 
B)  Type II supernovae 
C)  supermassive black holes. 
D)  sources outside the Galaxy that are otherwise unknown.

Question 5

Pulsating X-ray sources with periods of a few seconds are caused by

Accepted Answer

A)  the eclipsing of an X-ray-emitting star with a very hot surface by a cool companion in a close binary system. 
B)  the pulsation in radius, temperature, and hence luminosity of a hot Cepheid variable star with a surface temperature hot enough to emit X-rays. 
C)  matter falling violently onto the surface of a rotating neutron star from a close companion in a binary star system, causing an X-ray hot spot that disappears periodically behind the neutron star. 
D)  matter falling onto the surface of a very hot, rotating white dwarf star from an ordinary companion star in a binary system, producing an X-ray-emitting hot spot that disappears periodically behind the white dwarf. 
A)  the eclipsing of an X-ray-emitting star with a very hot surface by a cool companion in a close binary system. 
B)  the pulsation in radius, temperature, and hence luminosity of a hot Cepheid variable star with a surface temperature hot enough to emit X-rays. 
C)  matter falling violently onto the surface of a rotating neutron star from a close companion in a binary star system, causing an X-ray hot spot that disappears periodically behind the neutron star. 
D)  matter falling onto the surface of a very hot, rotating white dwarf star from an ordinary companion star in a binary system, producing an X-ray-emitting hot spot that disappears periodically behind the white dwarf.

Question 6

Measurements from distant galaxies indicate that supernovae should occur at a rate of 5 per century in a spiral galaxy such as the Milky Way, but only 3 have been recorded in this Galaxy in the past 1000 years. Explain.

Accepted Answer

A)  Most supernovae produce X-rays and radio waves, not visible light, and were hence invisible to earlier observers. 
B)  The majority of supernovae must have occurred in the plane of the Milky Way and hence were hidden from Earth by the dense gas and dust in the Milky Way plane. 
C)  The Milky Way Galaxy is somehow different, with much lower numbers of very massive stars in general, so many fewer stars have undergone supernova explosions. 
D)  Observers were not watching the sky carefully enough, particularly through the Dark Ages and over the past few centuries. 
A)  Most supernovae produce X-rays and radio waves, not visible light, and were hence invisible to earlier observers. 
B)  The majority of supernovae must have occurred in the plane of the Milky Way and hence were hidden from Earth by the dense gas and dust in the Milky Way plane. 
C)  The Milky Way Galaxy is somehow different, with much lower numbers of very massive stars in general, so many fewer stars have undergone supernova explosions. 
D)  Observers were not watching the sky carefully enough, particularly through the Dark Ages and over the past few centuries.

Question 7

A high-mass star near the end of its life undergoes successive cycles of energy generation in its core in which gravitational collapse increases the temperature to the point where a new nuclear fusion cycle generates sufficient energy to stop the collapse. This process does not work beyond the silicon-fusion cycle that produces iron. Explain.

Accepted Answer

A)  The pressure from high-energy photons and neutrinos at the very high core temperatures reached at this stage of development is finally sufficient to halt the collapse. 
B)  Electrostatic forces between the highly charged iron nuclei are sufficient to overcome the collapse and stabilize the stellar core. 
C)  Fusion of iron nuclei into heavier nuclei requires energy rather than producing excess energy and therefore will not produce the additional gas pressure to halt the collapse. 
D)  Iron nuclei are so large that they occupy all remaining space, so the collapse cannot continue. 
A)  The pressure from high-energy photons and neutrinos at the very high core temperatures reached at this stage of development is finally sufficient to halt the collapse. 
B)  Electrostatic forces between the highly charged iron nuclei are sufficient to overcome the collapse and stabilize the stellar core. 
C)  Fusion of iron nuclei into heavier nuclei requires energy rather than producing excess energy and therefore will not produce the additional gas pressure to halt the collapse. 
D)  Iron nuclei are so large that they occupy all remaining space, so the collapse cannot continue.

Question 8

What is believed to be the source of many ultrahigh-energy cosmic rays?

Accepted Answer

A)  active supernovae 
B)  globular clusters 
C)  supermassive black holes 
D)  quasars 
A)  active supernovae 
B)  globular clusters 
C)  supermassive black holes 
D)  quasars

Question 9

A white dwarf star, the surviving core of a low-mass star toward the end of its life, can be found on the Hertzsprung-Russell diagram

Accepted Answer

A)  at the upper-left end of the main sequence since its surface temperature is extremely high. 
B)  at the bottom end of the main sequence, along which it has evolved throughout its life. 
C)  below and to the left of the main sequence. 
D)  above and to the right of the main sequence since it evolved there after its hydrogen-fusion phase. 
A)  at the upper-left end of the main sequence since its surface temperature is extremely high. 
B)  at the bottom end of the main sequence, along which it has evolved throughout its life. 
C)  below and to the left of the main sequence. 
D)  above and to the right of the main sequence since it evolved there after its hydrogen-fusion phase.

Question 10

Pulsars emitting very regular radio and sometimes visible light pulses are what type of object?

Accepted Answer

A)  black holes, with material falling regularly into them 
B)  pulsating variable stars 
C)  rapidly rotating neutron stars 
D)  rapidly rotating binary star systems in which the stars undergo regular eclipses as seen from Earth 
A)  black holes, with material falling regularly into them 
B)  pulsating variable stars 
C)  rapidly rotating neutron stars 
D)  rapidly rotating binary star systems in which the stars undergo regular eclipses as seen from Earth

Question 11

What physical process provides the energy for the ejection of a planetary nebula from a low-mass star?

Accepted Answer

A)  transfer of hydrogen-rich material onto the surface of a white dwarf from its companion in a binary star system 
B)  helium shell flashes in the helium fusion shell 
C)  core collapse and the ensuing shock wave 
D)  collision with another star 
A)  transfer of hydrogen-rich material onto the surface of a white dwarf from its companion in a binary star system 
B)  helium shell flashes in the helium fusion shell 
C)  core collapse and the ensuing shock wave 
D)  collision with another star

Question 12

The diameter of a typical planetary nebula, after 10,000 years of expansion, is

Accepted Answer

A)  about 1000 ly. 
B)  about 1 au. 
C)  only about 3 to 5 stellar diameters. 
D)  a few light-years. 
A)  about 1000 ly. 
B)  about 1 au. 
C)  only about 3 to 5 stellar diameters. 
D)  a few light-years.

Question 13

A pulsar is MOST probably formed

Accepted Answer

A)  at the center of a supernova explosion. 
B)  in the high-temperature core of a star as it evolves through its main-sequence phase. 
C)  in a huge gas cloud by collisions between stars. 
D)  just after the formation of a protostar by gravitational condensation. 
A)  at the center of a supernova explosion. 
B)  in the high-temperature core of a star as it evolves through its main-sequence phase. 
C)  in a huge gas cloud by collisions between stars. 
D)  just after the formation of a protostar by gravitational condensation.

Question 14

Which major astronomical event was apparently recorded faithfully by Chinese astronomers in the Sung Dynasty in A.D. 1054?

Accepted Answer

A)  supernova explosion in the Milky Way Galaxy 
B)  total eclipse of the Sun over China 
C)  rare passage of the planet Venus across the face of the Sun, a solar transit 
D)  discovery of the planet Mercury 
A)  supernova explosion in the Milky Way Galaxy 
B)  total eclipse of the Sun over China 
C)  rare passage of the planet Venus across the face of the Sun, a solar transit 
D)  discovery of the planet Mercury

Question 15

Suppose astronomers discover a nova in a distant galaxy. What do they immediately know about the star that gave rise to this nova?

Accepted Answer

A)  The star is a white dwarf in a binary system in which the other star fills its Roche lobe. 
B)  The star is a neutron star in a binary system in which the other star is a white dwarf. 
C)  The star is a neutron star in a binary system in which the other star fills its Roche lobe. 
D)  The star is a black hole in a binary system in which the other star fills its Roche lobe. 
A)  The star is a white dwarf in a binary system in which the other star fills its Roche lobe. 
B)  The star is a neutron star in a binary system in which the other star is a white dwarf. 
C)  The star is a neutron star in a binary system in which the other star fills its Roche lobe. 
D)  The star is a black hole in a binary system in which the other star fills its Roche lobe.

Question 16

As time progresses, the pulse rate for MOST solitary pulsars

Accepted Answer

A)  varies periodically as the neutron star undergoes periodic expansions and contractions. 
B)  slows down since rotational energy is being used to generate the pulses. 
C)  speeds up as the neutron star slowly contracts under gravity. 
D)  remains absolutely constant; pulsars provide ideal frequency standards, or clocks. 
A)  varies periodically as the neutron star undergoes periodic expansions and contractions. 
B)  slows down since rotational energy is being used to generate the pulses. 
C)  speeds up as the neutron star slowly contracts under gravity. 
D)  remains absolutely constant; pulsars provide ideal frequency standards, or clocks.

Question 17

A pulsar is a(n)

Accepted Answer

A)  rapidly rotating neutron star, emitting beams of radio energy and sometimes X-ray and visible energy. 
B)  binary star in which matter from one star is falling onto the second star. 
C)  object at the center of each galaxy, supplying energy from its rapid rotation. 
D)  pulsating star, in which size, temperature, and light intensity vary regularly. 
A)  rapidly rotating neutron star, emitting beams of radio energy and sometimes X-ray and visible energy. 
B)  binary star in which matter from one star is falling onto the second star. 
C)  object at the center of each galaxy, supplying energy from its rapid rotation. 
D)  pulsating star, in which size, temperature, and light intensity vary regularly.

Question 18

Recent observations reveal that the outer parts of novae are composed of

Accepted Answer

A)  smooth shells of expanding gas. 
B)  shells that originate from bipolar jets. 
C)  thousands of clumps of gas. 
D)  warped rings of gas and dust. 
A)  smooth shells of expanding gas. 
B)  shells that originate from bipolar jets. 
C)  thousands of clumps of gas. 
D)  warped rings of gas and dust.

Question 19

During the collapse of a massive star the core will rebound outward in a process called "core bounce". What causes this?

Accepted Answer

A)  A flood of neutrinos is released and pushes outward on the core. 
B)  A flood of high-energy gamma rays is released and pushes outward on the core. 
C)  The collapsing core reaches the density of nuclear matter and stiffens. 
D)  Radioactivity develops because of the tremendous amount of energy available, and the radiation reverses the movement of the core. 
A)  A flood of neutrinos is released and pushes outward on the core. 
B)  A flood of high-energy gamma rays is released and pushes outward on the core. 
C)  The collapsing core reaches the density of nuclear matter and stiffens. 
D)  Radioactivity develops because of the tremendous amount of energy available, and the radiation reverses the movement of the core.

Question 20

A binary system contains a pulsar whose beam intercepts the atmosphere of its main-sequence companion. This system contains a

Accepted Answer

A)  magnetar. 
B)  soft gamma-ray repeater. 
C)  black widow pulsar. 
D)  X-ray burster. 
A)  magnetar. 
B)  soft gamma-ray repeater. 
C)  black widow pulsar. 
D)  X-ray burster.

The interiors of white dwarf stars are characteristically

In what manner does an isolated white dwarf generate energy?

The light from the most recent supernova that was visible to the unaided eye arrived at Earth in

Fast radio bursts originate from

Pulsating X-ray sources with periods of a few seconds are caused by

Measurements from distant galaxies indicate that supernovae should occur at a rate of 5 per century in a spiral galaxy such as the Milky Way, but only 3 have been recorded in this Galaxy in the past 1000 years. Explain.

What is believed to be the source of many ultrahigh-energy cosmic rays?

A white dwarf star, the surviving core of a low-mass star toward the end of its life, can be found on the Hertzsprung-Russell diagram

Pulsars emitting very regular radio and sometimes visible light pulses are what type of object?

What physical process provides the energy for the ejection of a planetary nebula from a low-mass star?

The diameter of a typical planetary nebula, after 10,000 years of expansion, is

A pulsar is MOST probably formed

Which major astronomical event was apparently recorded faithfully by Chinese astronomers in the Sung Dynasty in A.D. 1054?

Suppose astronomers discover a nova in a distant galaxy. What do they immediately know about the star that gave rise to this nova?

As time progresses, the pulse rate for MOST solitary pulsars

A pulsar is a(n)

Recent observations reveal that the outer parts of novae are composed of

During the collapse of a massive star the core will rebound outward in a process called "core bounce". What causes this?

A binary system contains a pulsar whose beam intercepts the atmosphere of its main-sequence companion. This system contains a

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

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Exam 14: The Death of Stars

The interiors of white dwarf stars are characteristically

In what manner does an isolated white dwarf generate energy?

The light from the most recent supernova that was visible to the unaided eye arrived at Earth in

Fast radio bursts originate from

Pulsating X-ray sources with periods of a few seconds are caused by

Measurements from distant galaxies indicate that supernovae should occur at a rate of 5 per century in a spiral galaxy such as the Milky Way, but only 3 have been recorded in this Galaxy in the past 1000 years. Explain.

What is believed to be the source of many ultrahigh-energy cosmic rays?

A white dwarf star, the surviving core of a low-mass star toward the end of its life, can be found on the Hertzsprung-Russell diagram

Pulsars emitting very regular radio and sometimes visible light pulses are what type of object?

What physical process provides the energy for the ejection of a planetary nebula from a low-mass star?

The diameter of a typical planetary nebula, after 10,000 years of expansion, is

A pulsar is MOST probably formed

Which major astronomical event was apparently recorded faithfully by Chinese astronomers in the Sung Dynasty in A.D. 1054?

Suppose astronomers discover a nova in a distant galaxy. What do they immediately know about the star that gave rise to this nova?

As time progresses, the pulse rate for MOST solitary pulsars

A pulsar is a(n)

Recent observations reveal that the outer parts of novae are composed of

During the collapse of a massive star the core will rebound outward in a process called "core bounce". What causes this?

A binary system contains a pulsar whose beam intercepts the atmosphere of its main-sequence companion. This system contains a

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