Question 1

The capture of free neutrons by heavy atomic nuclei is

Accepted Answer

A)  easy because neutron capture always produces a stable product nucleus. 
B)  easy because the neutron has no electric charge. 
C)  difficult,unless the nucleus is already unstable. 
D)  difficult,unless the neutron is moving rapidly. 
A)  easy because neutron capture always produces a stable product nucleus. 
B)  easy because the neutron has no electric charge. 
C)  difficult,unless the nucleus is already unstable. 
D)  difficult,unless the neutron is moving rapidly.

Question 2

What prevents a neutron star from collapsing and becoming a black hole?

Accepted Answer

A)  Gravity in the neutron star is balanced by an outward force due to neutron degeneracy. 
B)  Neutron stars are held up by centrifugal force due to their rapid rotation. 
C)  Neutron stars are solid,and like other solid spheres,are held up by the repulsive force between atoms in the solid. 
D)  Gravity in the neutron star is balanced by an outward force due to gas pressure,as in the Sun. 
A)  Gravity in the neutron star is balanced by an outward force due to neutron degeneracy. 
B)  Neutron stars are held up by centrifugal force due to their rapid rotation. 
C)  Neutron stars are solid,and like other solid spheres,are held up by the repulsive force between atoms in the solid. 
D)  Gravity in the neutron star is balanced by an outward force due to gas pressure,as in the Sun.

Question 3

What range in the electromagnetic spectrum was being observed when the first pulsars were discovered?

Accepted Answer

A)  X-ray 
B)  Visible 
C)  Radio 
D)  Gamma rays 
A)  X-ray 
B)  Visible 
C)  Radio 
D)  Gamma rays

Question 4

What is the difference between a nova and a supernova?

Accepted Answer

A nova is produced by an explosion on a

Question 5

How is a pulsar like a lighthouse?

Accepted Answer

Intense beams of radiation emanate from

Question 6

What is the event horizon of a black hole?

Accepted Answer

A)  The "surface" from the inside of which nothing can escape 
B)  The "surface" at which all "events" or activity appear to happen because of general relativity 
C)  The infinitesimally small volume at the center of the black hole that contains all of the black hole's mass 
D)  The "surface" inside which any object entering will leave with greater energy than that with which it entered 
A)  The "surface" from the inside of which nothing can escape 
B)  The "surface" at which all "events" or activity appear to happen because of general relativity 
C)  The infinitesimally small volume at the center of the black hole that contains all of the black hole's mass 
D)  The "surface" inside which any object entering will leave with greater energy than that with which it entered

Question 7

Which of the following astronomical objects are most closely associated with pulsars?

Accepted Answer

A)  Neutron stars 
B)  Black holes 
C)  Red-giant stars 
D)  White-dwarf stars 
A)  Neutron stars 
B)  Black holes 
C)  Red-giant stars 
D)  White-dwarf stars

Question 8

In what year was the first pulsar discovered?

Accepted Answer

A)  1978 
B)  1967 
C)  1960 
D)  1930 
A)  1978 
B)  1967 
C)  1960 
D)  1930

Question 9

Where would you look for an event horizon?

Accepted Answer

A)  At the edge of the visible universe 
B)  At the photosphere of a star (e.g. ,the Sun) 
C)  Around a black hole 
D)  In the magnetosphere of a neutron star 
A)  At the edge of the visible universe 
B)  At the photosphere of a star (e.g. ,the Sun) 
C)  Around a black hole 
D)  In the magnetosphere of a neutron star

Question 10

How is a pulsar's magnetic field strength determined?

Accepted Answer

A)  The number of pulses per second 
B)  The splitting of its spectral lines 
C)  The color of light from it 
D)  The brightness of it 
A)  The number of pulses per second 
B)  The splitting of its spectral lines 
C)  The color of light from it 
D)  The brightness of it

Question 11

The very strong magnetic field of a neutron star is created by

Accepted Answer

A)  a burst of neutrinos produced by the supernova explosion because this would be the equivalent of a very large electrical current flowing for a short time. 
B)  the collapse of a star,which significantly intensifies the original weak magnetic field of the star. 
C)  differential rotation of the neutron star,its equator rotating faster than the poles,similar to sunspot formation. 
D)  turbulence generated in electrical plasmas during the collapse of a star,even though this star had no magnetic field originally. 
A)  a burst of neutrinos produced by the supernova explosion because this would be the equivalent of a very large electrical current flowing for a short time. 
B)  the collapse of a star,which significantly intensifies the original weak magnetic field of the star. 
C)  differential rotation of the neutron star,its equator rotating faster than the poles,similar to sunspot formation. 
D)  turbulence generated in electrical plasmas during the collapse of a star,even though this star had no magnetic field originally.

Question 12

Which of the following is NOT one of the reasons we believe gamma-ray bursters are supernova explosions in distant galaxies rather than eruptions in the nuclei of active galaxies?

Accepted Answer

A)  Afterglow spectra are very similar to known supernova spectra. 
B)  The expanding shell of gas that follows the explosion is similar to that following a supernova. 
C)  Gamma-ray bursters do not appear at the centers of their host galaxies. 
D)  The amount of energy released in a burster is similar to that released in a normal supernova. 
A)  Afterglow spectra are very similar to known supernova spectra. 
B)  The expanding shell of gas that follows the explosion is similar to that following a supernova. 
C)  Gamma-ray bursters do not appear at the centers of their host galaxies. 
D)  The amount of energy released in a burster is similar to that released in a normal supernova.

Question 13

A typical supernova,in the hours following its explosion,is as bright as

Accepted Answer

A)  1000 typical spiral galaxies. 
B)  an entire galaxy. 
C)  1000 Sun-like stars. 
D)  a million Sun-like stars. 
A)  1000 typical spiral galaxies. 
B)  an entire galaxy. 
C)  1000 Sun-like stars. 
D)  a million Sun-like stars.

Question 14

In general,an isolated pulsar speeds up as it ages,so its pulse period decreases.

Accepted Answer

A) True 
 B)False

Question 15

Neutron stars are believed to be created primarily by

Accepted Answer

A)  explosions in main-sequence stars. 
B)  Type Ia supernovae (explosions in white dwarfs). 
C)  Type II supernovae (explosions in high-mass stars). 
D)  supernovae of either Type Ia or Type II. 
A)  explosions in main-sequence stars. 
B)  Type Ia supernovae (explosions in white dwarfs). 
C)  Type II supernovae (explosions in high-mass stars). 
D)  supernovae of either Type Ia or Type II.

Question 16

At first,it was thought that nothing could ever escape from a black hole,yet astronomers are now locating black hole candidates by the X-rays they emit.Do they really see X-rays coming from a black hole?

Accepted Answer

A)  The X-rays come from highly compressed matter in the accretion disk outside the event horizon of the black hole. 
B)  The black hole modifies spacetime around it so much that particles and X-rays are created in the vacuum itself,just outside the event horizon. 
C)  The X-rays are produced by vibrations of the black hole itself,and therefore they come from the event horizon,and not from inside the black hole. 
D)  X-rays are neither light nor matter and therefore can escape from inside the black hole. 
A)  The X-rays come from highly compressed matter in the accretion disk outside the event horizon of the black hole. 
B)  The black hole modifies spacetime around it so much that particles and X-rays are created in the vacuum itself,just outside the event horizon. 
C)  The X-rays are produced by vibrations of the black hole itself,and therefore they come from the event horizon,and not from inside the black hole. 
D)  X-rays are neither light nor matter and therefore can escape from inside the black hole.

Question 17

Some pulsars can be reaccelerated to dizzying rotations in some cases if they are

Accepted Answer

A)  surrounded by dust and gas. 
B)  members of a binary star system. 
C)  producing a strong magnetic field. 
D)  emitting beams of radiation. 
A)  surrounded by dust and gas. 
B)  members of a binary star system. 
C)  producing a strong magnetic field. 
D)  emitting beams of radiation.

Question 18

If the Sun were replaced by a 1-solar-mass black hole,then Earth would

Accepted Answer

A)  continue to orbit the black hole in precisely its present orbit. 
B)  move into an elliptical orbit passing close to the black hole,with its farthest distance from the black hole equal to 1 AU. 
C)  spiral quickly into the black hole. 
D)  head off into interstellar space along a straight line at a tangent to its original orbit around the Sun. 
A)  continue to orbit the black hole in precisely its present orbit. 
B)  move into an elliptical orbit passing close to the black hole,with its farthest distance from the black hole equal to 1 AU. 
C)  spiral quickly into the black hole. 
D)  head off into interstellar space along a straight line at a tangent to its original orbit around the Sun.

Question 19

Evidence for the existence of supermassive black holes has now been found

Accepted Answer

A)  in every known galaxy. 
B)  nowhere in our observable universe,although the existence of such black holes has been predicted by theory. 
C)  in several dozen galaxies. 
D)  in only one galaxy,our own Milky Way Galaxy. 
A)  in every known galaxy. 
B)  nowhere in our observable universe,although the existence of such black holes has been predicted by theory. 
C)  in several dozen galaxies. 
D)  in only one galaxy,our own Milky Way Galaxy.

Question 20

The sequence of thermonuclear fusion processes inside massive stars can transform elements such as carbon,oxygen,and so forth,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)  It has been found that iron nuclei never undergo fusion reactions. 
B)  The magnetic properties of iron produce extra repulsion that,along with the electrostatic repulsion,prevents fusion of iron nuclei with protons. 
C)  Iron is the heaviest possible element in nature,and fusion of heavier elements is not possible. 
D)  The electrostatic repulsion between the iron nucleus and the proton is so great that fusion requires extra energy,rather than releasing it. 
A)  It has been found that iron nuclei never undergo fusion reactions. 
B)  The magnetic properties of iron produce extra repulsion that,along with the electrostatic repulsion,prevents fusion of iron nuclei with protons. 
C)  Iron is the heaviest possible element in nature,and fusion of heavier elements is not possible. 
D)  The electrostatic repulsion between the iron nucleus and the proton is so great that fusion requires extra energy,rather than releasing it.

The capture of free neutrons by heavy atomic nuclei is

What prevents a neutron star from collapsing and becoming a black hole?

What range in the electromagnetic spectrum was being observed when the first pulsars were discovered?

What is the difference between a nova and a supernova?

How is a pulsar like a lighthouse?

What is the event horizon of a black hole?

Which of the following astronomical objects are most closely associated with pulsars?

In what year was the first pulsar discovered?

Where would you look for an event horizon?

How is a pulsar's magnetic field strength determined?

The very strong magnetic field of a neutron star is created by

Which of the following is NOT one of the reasons we believe gamma-ray bursters are supernova explosions in distant galaxies rather than eruptions in the nuclei of active galaxies?

A typical supernova,in the hours following its explosion,is as bright as

In general,an isolated pulsar speeds up as it ages,so its pulse period decreases.

Neutron stars are believed to be created primarily by

At first,it was thought that nothing could ever escape from a black hole,yet astronomers are now locating black hole candidates by the X-rays they emit.Do they really see X-rays coming from a black hole?

Some pulsars can be reaccelerated to dizzying rotations in some cases if they are

If the Sun were replaced by a 1-solar-mass black hole,then Earth would

Evidence for the existence of supermassive black holes has now been found

The sequence of thermonuclear fusion processes inside massive stars can transform elements such as carbon,oxygen,and so forth,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?

Predicting the Motions of the Stars, Sun, and Moon

Decoding the Hidden Messages in Starlight

Analyzing Scales and Motions of the Universe

Exploring Our Evolving Solar System

Uncovering Earths Systems

Exploring Terrestrial Surface Processes and Atmospheres

Observing the Dynamic Giant Planets

Looking for Life Beyond Earth

Probing the Dynamic Sun

Observing Properties of Distant Stars

Inferring Patterns in Star Life Cycles

Exploring Our Galaxy

Investigating Other Galaxies

Observing the Evolution of the Universe

Filters

Exam 12: Predicting the Violent End of the Largest Stars

The capture of free neutrons by heavy atomic nuclei is

What prevents a neutron star from collapsing and becoming a black hole?

What range in the electromagnetic spectrum was being observed when the first pulsars were discovered?

What is the difference between a nova and a supernova?

How is a pulsar like a lighthouse?

What is the event horizon of a black hole?

Which of the following astronomical objects are most closely associated with pulsars?

In what year was the first pulsar discovered?

Where would you look for an event horizon?

How is a pulsar's magnetic field strength determined?

The very strong magnetic field of a neutron star is created by

Which of the following is NOT one of the reasons we believe gamma-ray bursters are supernova explosions in distant galaxies rather than eruptions in the nuclei of active galaxies?

A typical supernova,in the hours following its explosion,is as bright as

In general,an isolated pulsar speeds up as it ages,so its pulse period decreases.

Neutron stars are believed to be created primarily by

At first,it was thought that nothing could ever escape from a black hole,yet astronomers are now locating black hole candidates by the X-rays they emit.Do they really see X-rays coming from a black hole?

Some pulsars can be reaccelerated to dizzying rotations in some cases if they are

If the Sun were replaced by a 1-solar-mass black hole,then Earth would

Evidence for the existence of supermassive black holes has now been found

The sequence of thermonuclear fusion processes inside massive stars can transform elements such as carbon,oxygen,and so forth,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?

Predicting the Motions of the Stars, Sun, and Moon

Decoding the Hidden Messages in Starlight

Analyzing Scales and Motions of the Universe

Exploring Our Evolving Solar System

Uncovering Earths Systems

Exploring Terrestrial Surface Processes and Atmospheres

Observing the Dynamic Giant Planets

Looking for Life Beyond Earth

Probing the Dynamic Sun

Observing Properties of Distant Stars

Inferring Patterns in Star Life Cycles

Exploring Our Galaxy

Investigating Other Galaxies

Observing the Evolution of the Universe

Filters