Question 1

What happens to a photon that leaves the interior of a black hole aimed directly upward (radially outward)?

Accepted Answer

A)  This photon will be stopped and pulled back downward by the gravity of the black hole. 
B)  Since symmetry prohibits this photon from deflecting to either side, this is the only case in which a photon can escape from a black hole. But since it must be aimed precisely upward, this is a vanishingly small fraction of all the light inside the black hole. 
C)  This photon reflects from the ergoregion back to the singularity, where it is absorbed. 
D)  This photon becomes infinitely redshifted and ceases to exist. 
A)  This photon will be stopped and pulled back downward by the gravity of the black hole. 
B)  Since symmetry prohibits this photon from deflecting to either side, this is the only case in which a photon can escape from a black hole. But since it must be aimed precisely upward, this is a vanishingly small fraction of all the light inside the black hole. 
C)  This photon reflects from the ergoregion back to the singularity, where it is absorbed. 
D)  This photon becomes infinitely redshifted and ceases to exist.

Question 2

Place two identical 3-solar-mass black holes side by side.Add 1 solar mass of neutrons to the left-hand one and 1 solar mass of protons to the right-hand one.How will these two black holes differ?

Accepted Answer

A)  The black holes will not differ at all since protons and neutrons are transformed into a common type of uncharged matter. 
B)  The left-hand black hole will have a stronger gravitational field than the right-hand one because a neutron is heavier than a proton. 
C)  The left-hand black hole will emit electrons and neutrinos as its neutrons decay into protons. 
D)  The left-hand black hole will be electrically neutral and the right-hand one will have an enormous electric charge. 
A)  The black holes will not differ at all since protons and neutrons are transformed into a common type of uncharged matter. 
B)  The left-hand black hole will have a stronger gravitational field than the right-hand one because a neutron is heavier than a proton. 
C)  The left-hand black hole will emit electrons and neutrinos as its neutrons decay into protons. 
D)  The left-hand black hole will be electrically neutral and the right-hand one will have an enormous electric charge.

Question 3

Helium nuclear reactions take place in a shell around the core of a low-mass star during its:

Accepted Answer

A)  horizontal-branch phase. 
B)  first red giant phase. 
C)  main-sequence phase. 
D)  asymptotic giant branch phase. 
A)  horizontal-branch phase. 
B)  first red giant phase. 
C)  main-sequence phase. 
D)  asymptotic giant branch phase.

Question 4

We have seen that the generation of magnetic fields requires both a rapid rotation and a fluid interior for the flow of currents of charged particles.But neutrons are electrically neutral,so how can a neutron star generate a magnetic field?

Accepted Answer

A)  Neutrons in neutron degeneracy in a neutron star acquire an electric charge. 
B)  Because the neutrons in a neutron star flow through a superconducting medium, they do not need to carry an electric charge in order to constitute a current. 
C)  The enormous amounts of friction experienced by degenerate neutrons cause electric charges to build up on their surfaces, like static electricity. 
D)  Neutron stars actually contain some protons and electrons, which carry the electric currents. 
A)  Neutrons in neutron degeneracy in a neutron star acquire an electric charge. 
B)  Because the neutrons in a neutron star flow through a superconducting medium, they do not need to carry an electric charge in order to constitute a current. 
C)  The enormous amounts of friction experienced by degenerate neutrons cause electric charges to build up on their surfaces, like static electricity. 
D)  Neutron stars actually contain some protons and electrons, which carry the electric currents.

Question 5

A sequence of thermonuclear fusion processes inside massive stars can continue to transform the nuclei of elements such as carbon and oxygen into heavier nuclei and also generate excess energy up to a limit beyond which no further energy-producing reactions can occur.The element that is produced when this limit is reached is:

Accepted Answer

A)  oxygen. 
B)  iron. 
C)  silicon. 
D)  uranium. 
A)  oxygen. 
B)  iron. 
C)  silicon. 
D)  uranium.

Question 6

What is a primordial black hole?

Accepted Answer

A)  a black hole created during the formation of the universe 
B)  a black hole not in orbit around a normal star 
C)  a black hole created during the formation of the solar system 
D)  a black hole at the center of a galaxy 
A)  a black hole created during the formation of the universe 
B)  a black hole not in orbit around a normal star 
C)  a black hole created during the formation of the solar system 
D)  a black hole at the center of a galaxy

Question 7

Helium nuclear reactions (helium fusion)produce primarily:

Accepted Answer

A)  carbon and oxygen. 
B)  carbon and silicon. 
C)  iron. 
D)  oxygen and neon. 
A)  carbon and oxygen. 
B)  carbon and silicon. 
C)  iron. 
D)  oxygen and neon.

Question 8

Which phenomenon is NOT associated with a rotating neutron star?

Accepted Answer

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

Question 9

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

Accepted Answer

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

Question 10

The escape velocity for material inside a black hole is:

Accepted Answer

A)  zero. 
B)  infinite. 
C)  greater than the speed of light. 
D)  twice that from a neutron star. 
A)  zero. 
B)  infinite. 
C)  greater than the speed of light. 
D)  twice that from a neutron star.

Question 11

In 2004,astronomers made a significant discovery that enabled them to test some of the predictions of general relativity.What was this discovery?

Accepted Answer

A)  a neutron star with a mass more than a hundred times the mass of the Sun 
B)  two neutron stars collided with each other 
C)  a pulsar that was not precessing and, in fact, that aimed its radiation beam directly at Earth 
D)  two pulsars in orbit around each other 
A)  a neutron star with a mass more than a hundred times the mass of the Sun 
B)  two neutron stars collided with each other 
C)  a pulsar that was not precessing and, in fact, that aimed its radiation beam directly at Earth 
D)  two pulsars in orbit around each other

Question 12

The "star" that is seen at the center of a planetary nebula is:

Accepted Answer

A)  a small, hot, and very dense white dwarf star. 
B)  composed almost entirely of neutrons and spinning rapidly. 
C)  the accretion disk around a black hole. 
D)  a planet in the process of formation. 
A)  a small, hot, and very dense white dwarf star. 
B)  composed almost entirely of neutrons and spinning rapidly. 
C)  the accretion disk around a black hole. 
D)  a planet in the process of formation.

Question 13

The accretion disk surrounding a black hole is characterized by the emission of:

Accepted Answer

A)  red light. 
B)  blue light. 
C)  radio waves. 
D)  X-rays. 
A)  red light. 
B)  blue light. 
C)  radio waves. 
D)  X-rays.

Question 14

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 15

Suppose that a neutron star of 2.9 solar masses is part of a binary star system in which the other star is a normal giant star.What would happen if one solar mass of material were transferred onto the neutron star from its companion?

Accepted Answer

A)  The neutron star would explode as a supernova. 
B)  The neutron degeneracy pressure inside the neutron star would increase to balance the increased gravitational force in the neutron star. 
C)  The increased gravitational force would transform the neutrons into quarks, and the neutron star would reestablish equilibrium as a quark star of smaller diameter. 
D)  The neutron star would collapse and become a black hole. 
A)  The neutron star would explode as a supernova. 
B)  The neutron degeneracy pressure inside the neutron star would increase to balance the increased gravitational force in the neutron star. 
C)  The increased gravitational force would transform the neutrons into quarks, and the neutron star would reestablish equilibrium as a quark star of smaller diameter. 
D)  The neutron star would collapse and become a black hole.

Question 16

In the binary pulsar Hercules X-1 the periodic Doppler shift,once every 1.7 days,was discovered rather quickly.Even though the binary pulsar Centaurus X-3 was discovered earlier,its Doppler shift was discovered only much later.What might be a reason for this?

Accepted Answer

A)  The orbital plane of Centaurus X-3 is in the plane of the sky and therefore has no radial motion and no Doppler shift. 
B)  Centaurus X-3 is too far away to see the Doppler shift easily. 
C)  The orbital period of Centaurus X-3, 2087 days, suggests that it moves relatively slowly. 
D)  The binary companion of Centaurus X-3 is a black hole that distorts the pattern of its radiation output. 
A)  The orbital plane of Centaurus X-3 is in the plane of the sky and therefore has no radial motion and no Doppler shift. 
B)  Centaurus X-3 is too far away to see the Doppler shift easily. 
C)  The orbital period of Centaurus X-3, 2087 days, suggests that it moves relatively slowly. 
D)  The binary companion of Centaurus X-3 is a black hole that distorts the pattern of its radiation output.

Question 17

What property of the longer-living gamma-ray bursters indicates that they are located at large ("cosmological")distances from Earth?

Accepted Answer

A)  highly redshifted emission lines seen in their visible spectrum from the burster's nucleus 
B)  the small apparent sizes of the objects producing the bursts 
C)  absorption lines in the visible spectra of their remnant glow, due to intergalactic clouds between them and Earth 
D)  the faintness of these bursts 
A)  highly redshifted emission lines seen in their visible spectrum from the burster's nucleus 
B)  the small apparent sizes of the objects producing the bursts 
C)  absorption lines in the visible spectra of their remnant glow, due to intergalactic clouds between them and Earth 
D)  the faintness of these bursts

Question 18

When the mass of an object exceeds about three solar masses,the object is believed to collapse to form a(n):

Accepted Answer

A)  neutron star. 
B)  white dwarf. 
C)  electron star. 
D)  black hole. 
A)  neutron star. 
B)  white dwarf. 
C)  electron star. 
D)  black hole.

Question 19

In the context of black holes,what is a wormhole?

Accepted Answer

A)  a "tunnel" of undistorted space through an event horizon allowing objects to enter and leave a black hole without being torn apart 
B)  a direct connection from any black hole to another part of spacetime 
C)  a small black hole through a solid object such as a planet 
D)  a direct connection from a rotating black hole to another part of spacetime 
A)  a "tunnel" of undistorted space through an event horizon allowing objects to enter and leave a black hole without being torn apart 
B)  a direct connection from any black hole to another part of spacetime 
C)  a small black hole through a solid object such as a planet 
D)  a direct connection from a rotating black hole to another part of spacetime

Question 20

The formation of an iron core is an important stage in the development of a supernova because:

Accepted Answer

A)  iron nuclei cannot participate in nuclear reactions. 
B)  when iron nuclei undergo nuclear reactions, they always absorb energy. 
C)  when iron nuclei undergo nuclear reactions, they always give out energy. 
D)  iron nuclei make the core magnetic. 
A)  iron nuclei cannot participate in nuclear reactions. 
B)  when iron nuclei undergo nuclear reactions, they always absorb energy. 
C)  when iron nuclei undergo nuclear reactions, they always give out energy. 
D)  iron nuclei make the core magnetic.

What happens to a photon that leaves the interior of a black hole aimed directly upward (radially outward)?

Place two identical 3-solar-mass black holes side by side.Add 1 solar mass of neutrons to the left-hand one and 1 solar mass of protons to the right-hand one.How will these two black holes differ?

Helium nuclear reactions take place in a shell around the core of a low-mass star during its:

We have seen that the generation of magnetic fields requires both a rapid rotation and a fluid interior for the flow of currents of charged particles.But neutrons are electrically neutral,so how can a neutron star generate a magnetic field?

What is a primordial black hole?

Helium nuclear reactions (helium fusion)produce primarily:

Which phenomenon is NOT associated with a rotating neutron star?

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

The escape velocity for material inside a black hole is:

In 2004,astronomers made a significant discovery that enabled them to test some of the predictions of general relativity.What was this discovery?

The "star" that is seen at the center of a planetary nebula is:

The accretion disk surrounding a black hole is characterized by the emission of:

A pulsar is MOST probably formed:

Suppose that a neutron star of 2.9 solar masses is part of a binary star system in which the other star is a normal giant star.What would happen if one solar mass of material were transferred onto the neutron star from its companion?

In the binary pulsar Hercules X-1 the periodic Doppler shift,once every 1.7 days,was discovered rather quickly.Even though the binary pulsar Centaurus X-3 was discovered earlier,its Doppler shift was discovered only much later.What might be a reason for this?

What property of the longer-living gamma-ray bursters indicates that they are located at large ("cosmological")distances from Earth?

When the mass of an object exceeds about three solar masses,the object is believed to collapse to form a(n):

In the context of black holes,what is a wormhole?

The formation of an iron core is an important stage in the development of a supernova because:

Discovering the Night Sky

Gravitation and the Waltz of the Planets

Light and Telescopes

Formation of the Solar System and Other Planetary Systems

Exoplanets

The Terrestrial Planets and Their Moons

The Outer Planets and Their Moons

Vagabonds of the Solar System

The Sun: Our Extraordinary Ordinary Star

Characterizing Stars

The Lives of the Stars From Birth Through Middle Age

The Galaxies

Cosmology

Astrobiology

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Exam 12: The Deaths and Remnants of Stars

What happens to a photon that leaves the interior of a black hole aimed directly upward (radially outward)?

Place two identical 3-solar-mass black holes side by side.Add 1 solar mass of neutrons to the left-hand one and 1 solar mass of protons to the right-hand one.How will these two black holes differ?

Helium nuclear reactions take place in a shell around the core of a low-mass star during its:

We have seen that the generation of magnetic fields requires both a rapid rotation and a fluid interior for the flow of currents of charged particles.But neutrons are electrically neutral,so how can a neutron star generate a magnetic field?

What is a primordial black hole?

Helium nuclear reactions (helium fusion)produce primarily:

Which phenomenon is NOT associated with a rotating neutron star?

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

The escape velocity for material inside a black hole is:

In 2004,astronomers made a significant discovery that enabled them to test some of the predictions of general relativity.What was this discovery?

The "star" that is seen at the center of a planetary nebula is:

The accretion disk surrounding a black hole is characterized by the emission of:

A pulsar is MOST probably formed:

Suppose that a neutron star of 2.9 solar masses is part of a binary star system in which the other star is a normal giant star.What would happen if one solar mass of material were transferred onto the neutron star from its companion?

In the binary pulsar Hercules X-1 the periodic Doppler shift,once every 1.7 days,was discovered rather quickly.Even though the binary pulsar Centaurus X-3 was discovered earlier,its Doppler shift was discovered only much later.What might be a reason for this?

What property of the longer-living gamma-ray bursters indicates that they are located at large ("cosmological")distances from Earth?

When the mass of an object exceeds about three solar masses,the object is believed to collapse to form a(n):

In the context of black holes,what is a wormhole?

The formation of an iron core is an important stage in the development of a supernova because:

Discovering the Night Sky

Gravitation and the Waltz of the Planets

Light and Telescopes

Formation of the Solar System and Other Planetary Systems

Exoplanets

The Terrestrial Planets and Their Moons

The Outer Planets and Their Moons

Vagabonds of the Solar System

The Sun: Our Extraordinary Ordinary Star

Characterizing Stars

The Lives of the Stars From Birth Through Middle Age

The Galaxies

Cosmology

Astrobiology

Filters