Question 1

X-ray bursters emit occasional and intense bursts of X-rays on top of a steady low-level X-ray emission.These bursts of X-rays are believed to be caused by:

Accepted Answer

A)  material from a companion star pulled into an accretion disk around a black hole, and, consequently, periodic clumps of material falling from the disk into the black hole and being compressed produce the X-rays. 
B)  material transferred onto the surface of a neutron star, causing the neutron star to collapse suddenly into a black hole. 
C)  material transferred onto the surface of a neutron star in a binary system, then subsequently ignited in a thermonuclear explosion that leaves the neutron star intact to repeat the process. 
D)  material transferred onto the surface of a white dwarf in a binary star system, producing a thermonuclear explosion at the surface while leaving the white dwarf intact to repeat the process. 
A)  material from a companion star pulled into an accretion disk around a black hole, and, consequently, periodic clumps of material falling from the disk into the black hole and being compressed produce the X-rays. 
B)  material transferred onto the surface of a neutron star, causing the neutron star to collapse suddenly into a black hole. 
C)  material transferred onto the surface of a neutron star in a binary system, then subsequently ignited in a thermonuclear explosion that leaves the neutron star intact to repeat the process. 
D)  material transferred onto the surface of a white dwarf in a binary star system, producing a thermonuclear explosion at the surface while leaving the white dwarf intact to repeat the process.

Question 2

At the center of the remnant of a Type Ia supernova you would expect to find:

Accepted Answer

A)  a black hole or neutron star. 
B)  a white dwarf. 
C)  the binary companion of the supernova. 
D)  nothing special. 
A)  a black hole or neutron star. 
B)  a white dwarf. 
C)  the binary companion of the supernova. 
D)  nothing special.

Question 3

What happens to the surface 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 star is spun off into space to make a spiral structure known as a spiral galaxy. 
C)  The star is 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 star is spun off into space to make a spiral structure known as a spiral galaxy. 
C)  The star is 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 4

Some magnetars with particularly strong magnetic fields emit huge bursts of high- frequency radiation as well as output at other wavelengths.Such magnetars are called:

Accepted Answer

A)  soft gamma-ray repeaters. 
B)  hard gamma-ray repeaters. 
C)  neutron accretion disks. 
D)  ultra-high-frequency sources. 
A)  soft gamma-ray repeaters. 
B)  hard gamma-ray repeaters. 
C)  neutron accretion disks. 
D)  ultra-high-frequency sources.

Question 5

In which "frame of reference" would matter behave exactly as it would in a stationary frame of reference?

Accepted Answer

A)  accelerating downward in an elevator whose cable has broken 
B)  moving upward against gravity in an elevator as it accelerates from rest 
C)  moving at a constant velocity 
D)  moving at a constant speed in a circular path, such as in an orbit 
A)  accelerating downward in an elevator whose cable has broken 
B)  moving upward against gravity in an elevator as it accelerates from rest 
C)  moving at a constant velocity 
D)  moving at a constant speed in a circular path, such as in an orbit

Question 6

The luminosity of a typical supernova star during the initial phases of the explosion increases by a factor of:

Accepted Answer

A)  10⁸. 
B)  10⁶. 
C)  2-3 since the star is already very bright. 
D)  10³. 
A)  10⁸. 
B)  10⁶. 
C)  2-3 since the star is already very bright. 
D)  10³.

Question 7

Which statement is NOT a test of general relativity but rather a test of special relativity?

Accepted Answer

A)  The length of a moving object decreases when observed by a stationary observer. 
B)  The wavelength of light increases as it leaves a region of gravitational field. 
C)  Light travels in a curved path in a gravitational field. 
D)  The perihelion position of Mercury's orbit precesses more quickly than is predicted by Newtonian theory. 
A)  The length of a moving object decreases when observed by a stationary observer. 
B)  The wavelength of light increases as it leaves a region of gravitational field. 
C)  Light travels in a curved path in a gravitational field. 
D)  The perihelion position of Mercury's orbit precesses more quickly than is predicted by Newtonian theory.

Question 8

What mechanism in the vicinity of a star gives us a hint of the presence of a black hole as a companion to the star?

Accepted Answer

A)  The light from the companion star shows extreme redshift because of the gravitational field of the black hole. 
B)  The star periodically disappears from the viewpoint of Earth during its eclipses by the black hole as the two objects orbit each other. 
C)  The space near the star darkens, indicating that the black hole prevents the light from distant objects from reaching Earth. 
D)  Gas from the star, falling in toward a black hole, is compressed to very high densities and temperatures so that it emits an intense and rapidly fluctuating flux of X-rays. 
A)  The light from the companion star shows extreme redshift because of the gravitational field of the black hole. 
B)  The star periodically disappears from the viewpoint of Earth during its eclipses by the black hole as the two objects orbit each other. 
C)  The space near the star darkens, indicating that the black hole prevents the light from distant objects from reaching Earth. 
D)  Gas from the star, falling in toward a black hole, is compressed to very high densities and temperatures so that it emits an intense and rapidly fluctuating flux of X-rays.

Question 9

What finally halts the core collapse in the initial stages of the formation of a Type Ia supernova?

Accepted Answer

A)  The core becomes a singularity, with all matter concentrated at a single point. 
B)  The iron core stiffens when it reaches the density of nuclear matter, producing the core bounce. 
C)  The iron core becomes hot enough to begin fusion reactions which produce a uranium core. 
D)  The temperature becomes great enough to produce radioactive nuclei. 
A)  The core becomes a singularity, with all matter concentrated at a single point. 
B)  The iron core stiffens when it reaches the density of nuclear matter, producing the core bounce. 
C)  The iron core becomes hot enough to begin fusion reactions which produce a uranium core. 
D)  The temperature becomes great enough to produce radioactive nuclei.

Question 10

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 11

Low-mass stars can ascend the H-R diagram in two evolutionary phases called giant phases.What is the difference between them?

Accepted Answer

A)  In the first, the primary production of energy is from hydrogen burning in the core. In the second, the primary production of energy is from helium burning in the core. 
B)  In the first, the primary production of energy is from hydrogen burning in a shell around the core. In the second, the primary production of energy is from helium burning in a shell around the core. 
C)  In the first, the star's track on the Hertzsprung-Russell diagram lies along the red- giant branch. In the second, the track lies along the horizontal branch. 
D)  During the first red giant phase, the star moves up and to the right along the red giant branch. During the second red giant phase, the star's track is down and to the left along the same red giant branch. 
A)  In the first, the primary production of energy is from hydrogen burning in the core. In the second, the primary production of energy is from helium burning in the core. 
B)  In the first, the primary production of energy is from hydrogen burning in a shell around the core. In the second, the primary production of energy is from helium burning in a shell around the core. 
C)  In the first, the star's track on the Hertzsprung-Russell diagram lies along the red- giant branch. In the second, the track lies along the horizontal branch. 
D)  During the first red giant phase, the star moves up and to the right along the red giant branch. During the second red giant phase, the star's track is down and to the left along the same red giant branch.

Question 12

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

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 13

What is it that is actually located at the event horizon of a black hole?

Accepted Answer

A)  an infinitely dense concentration of mass 
B)  a magnetic field of immense strength 
C)  nothing specific 
D)  a sphere of photons 
A)  an infinitely dense concentration of mass 
B)  a magnetic field of immense strength 
C)  nothing specific 
D)  a sphere of photons

Question 14

Suppose you were far from a planet that had a very strong gravitational field,and a light wave reaches you from a source of hydrogen (Hα)light on the surface of the planet.When you observe an Hα light source in your own spaceship,the wavelength is 656.3 nm.What wavelength do you see when you look at the light source on the planet?

Accepted Answer

A)  shorter than 656.3 nm 
B)  longer than 656.3 nm 
C)  infinite since the source is in a gravitational field 
D)  656.3 nm, the same as from your light source 
A)  shorter than 656.3 nm 
B)  longer than 656.3 nm 
C)  infinite since the source is in a gravitational field 
D)  656.3 nm, the same as from your light source

Question 15

What happens to the magnetic field of a star that collapses to become a black hole?

Accepted Answer

A)  The magnetic field becomes infinitely intensified. 
B)  The magnetic field is radiated away; black holes never have magnetic fields. 
C)  The magnetic field becomes compressed and intensified by a factor equal to the ratio of the star's original diameter to the diameter of the event horizon. 
D)  The magnetic field becomes weaker by the ratio of the diameter of the black hole event horizon to the star's original diameter. 
A)  The magnetic field becomes infinitely intensified. 
B)  The magnetic field is radiated away; black holes never have magnetic fields. 
C)  The magnetic field becomes compressed and intensified by a factor equal to the ratio of the star's original diameter to the diameter of the event horizon. 
D)  The magnetic field becomes weaker by the ratio of the diameter of the black hole event horizon to the star's original diameter.

Question 16

Photodisintegration,the fissioning of iron nuclei into helium nuclei by high-energy gamma radiation,occurs only at the very end of the life of a massive star.Why can photodisintegration not occur earlier? Choose the answer that is NOT correct.

Accepted Answer

A)  Iron nuclei do not exist in anything but trace amounts before this stage. 
B)  Gamma radiation of sufficient energy is not produced before this stage. 
C)  The fissioning of an iron nucleus requires energy, and the energy-rich environment that allows fissioning to happen does not exist before this stage. 
D)  Under the conditions of the previous stages of evolution, iron (²⁶Fe) disappears as quickly as it is formed by combining with helium (⁴He) to produce zinc (³⁰Zn). 
A)  Iron nuclei do not exist in anything but trace amounts before this stage. 
B)  Gamma radiation of sufficient energy is not produced before this stage. 
C)  The fissioning of an iron nucleus requires energy, and the energy-rich environment that allows fissioning to happen does not exist before this stage. 
D)  Under the conditions of the previous stages of evolution, iron (²⁶Fe) disappears as quickly as it is formed by combining with helium (⁴He) to produce zinc (³⁰Zn).

Question 17

In an observation of a group of stars adjacent to the limb of the Sun during a total solar eclipse,which way will the nearest star to the solar limb appear to move because of the curvature of space near the Sun?

Accepted Answer

A)  toward the solar limb 
B)  away from the solar limb and toward the center of the Sun 
C)  in a direction parallel to the limb of the Sun 
D)  Light is unaffected by the curvature of space, so the star's position in the group will remain unchanged. 
A)  toward the solar limb 
B)  away from the solar limb and toward the center of the Sun 
C)  in a direction parallel to the limb of the Sun 
D)  Light is unaffected by the curvature of space, so the star's position in the group will remain unchanged.

Question 18

A white dwarf is at what stage of its evolution?

Accepted Answer

A)  protostar phase, just after formation, beginning to generate energy by nuclear fusion 
B)  main-sequence phase, "middle-aged," generating energy by fusion of hydrogen to helium 
C)  post-supernova stage, after the explosion of a star 
D)  very late phase of evolution, no longer generating energy 
A)  protostar phase, just after formation, beginning to generate energy by nuclear fusion 
B)  main-sequence phase, "middle-aged," generating energy by fusion of hydrogen to helium 
C)  post-supernova stage, after the explosion of a star 
D)  very late phase of evolution, no longer generating energy

Question 19

According to Einstein's general theory of relativity,a clock that ticks at a regular rate far from a source of gravity will appear to tick:

Accepted Answer

A)  at the same rate in a gravitational field if it is an atomic clock but at a slower rate if it is a mechanical clock. 
B)  at the same rate, wherever it is placed in a gravitational field. 
C)  slower the closer it comes to the source of gravity. 
D)  faster the closer it comes to the source of gravity. 
A)  at the same rate in a gravitational field if it is an atomic clock but at a slower rate if it is a mechanical clock. 
B)  at the same rate, wherever it is placed in a gravitational field. 
C)  slower the closer it comes to the source of gravity. 
D)  faster the closer it comes to the source of gravity.

Question 20

A planetary nebula is a:

Accepted Answer

A)  cloud of gas surrounding a very young star in which planets are expected to form. 
B)  spherical, rapidly expanding cloud of gas produced by a supernova explosion. 
C)  gas cloud surrounding a planet after its formation. 
D)  shell of gases ejected from the surface of red giant star. 
A)  cloud of gas surrounding a very young star in which planets are expected to form. 
B)  spherical, rapidly expanding cloud of gas produced by a supernova explosion. 
C)  gas cloud surrounding a planet after its formation. 
D)  shell of gases ejected from the surface of red giant star.

X-ray bursters emit occasional and intense bursts of X-rays on top of a steady low-level X-ray emission.These bursts of X-rays are believed to be caused by:

At the center of the remnant of a Type Ia supernova you would expect to find:

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

Some magnetars with particularly strong magnetic fields emit huge bursts of high- frequency radiation as well as output at other wavelengths.Such magnetars are called:

In which "frame of reference" would matter behave exactly as it would in a stationary frame of reference?

The luminosity of a typical supernova star during the initial phases of the explosion increases by a factor of:

Which statement is NOT a test of general relativity but rather a test of special relativity?

What mechanism in the vicinity of a star gives us a hint of the presence of a black hole as a companion to the star?

What finally halts the core collapse in the initial stages of the formation of a Type Ia supernova?

A pulsar is a(n):

Low-mass stars can ascend the H-R diagram in two evolutionary phases called giant phases.What is the difference between them?

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

What is it that is actually located at the event horizon of a black hole?

What happens to the magnetic field of a star that collapses to become a black hole?

Photodisintegration,the fissioning of iron nuclei into helium nuclei by high-energy gamma radiation,occurs only at the very end of the life of a massive star.Why can photodisintegration not occur earlier? Choose the answer that is NOT correct.

In an observation of a group of stars adjacent to the limb of the Sun during a total solar eclipse,which way will the nearest star to the solar limb appear to move because of the curvature of space near the Sun?

A white dwarf is at what stage of its evolution?

According to Einstein's general theory of relativity,a clock that ticks at a regular rate far from a source of gravity will appear to tick:

A planetary nebula is a:

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

Exam 12: The Deaths and Remnants of Stars

X-ray bursters emit occasional and intense bursts of X-rays on top of a steady low-level X-ray emission.These bursts of X-rays are believed to be caused by:

At the center of the remnant of a Type Ia supernova you would expect to find:

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

Some magnetars with particularly strong magnetic fields emit huge bursts of high- frequency radiation as well as output at other wavelengths.Such magnetars are called:

In which "frame of reference" would matter behave exactly as it would in a stationary frame of reference?

The luminosity of a typical supernova star during the initial phases of the explosion increases by a factor of:

Which statement is NOT a test of general relativity but rather a test of special relativity?

What mechanism in the vicinity of a star gives us a hint of the presence of a black hole as a companion to the star?

What finally halts the core collapse in the initial stages of the formation of a Type Ia supernova?

A pulsar is a(n):

Low-mass stars can ascend the H-R diagram in two evolutionary phases called giant phases.What is the difference between them?

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

What is it that is actually located at the event horizon of a black hole?

What happens to the magnetic field of a star that collapses to become a black hole?

Photodisintegration,the fissioning of iron nuclei into helium nuclei by high-energy gamma radiation,occurs only at the very end of the life of a massive star.Why can photodisintegration not occur earlier? Choose the answer that is NOT correct.

In an observation of a group of stars adjacent to the limb of the Sun during a total solar eclipse,which way will the nearest star to the solar limb appear to move because of the curvature of space near the Sun?

A white dwarf is at what stage of its evolution?

According to Einstein's general theory of relativity,a clock that ticks at a regular rate far from a source of gravity will appear to tick:

A planetary nebula is a:

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