Question 1

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 protonsE) C) and D)
F) A) and B)

Question 2

How much mass are planetary nebulae estimated to return to the interstellar medium each year over the Galaxy as a whole?

Accepted Answer

A)   about 50,000 solar masses
B)   about 5 × 10⁸ solar masses
C)   about 5 solar masses
D)   about 500 solar massesE) B) and C)
F) None of the above

Question 3

In the context of black holes,a singularity is a(n) :

Accepted Answer

A)   place just outside the event horizon of a rotating black hole where it is impossible to remain at rest.
B)   entry point in the event horizon of a black hole through which material is allowed to pass unhindered.
C)   place where a nonzero mass occupies zero volume.
D)   place where the escape velocity exactly equals the speed of light.E) None of the above
F) A) and B)

Question 4

What is photodisintegration?

Accepted Answer

A)   the heating and ejection of mass from the surface of a normal star by the radiation from an orbiting neutron star
B)   the destruction of a star by the pressure of the radiation inside it
C)   the splitting apart of atomic nuclei by gamma rays
D)   the ejection of a neutron or proton from an atomic nucleus, accompanied by the emission of a gamma rayE) A) and B)
F) A) and C)

Question 5

Consider a group of stars with masses up to eight times the mass of the Sun.Stars of which masses will end up as pure helium?

Accepted Answer

A)   less than 0.4 M
B)   0.4 M to 2 M only
C)   2 M to 8 M only
D)   all stars 0.4 M to 8 ME) A) and B)
F) B) and C)

Question 6

How does a white dwarf generate its energy?

Accepted Answer

A)   It no longer generates energy but is slowly cooling as it radiates away its heat.
B)   Nuclear fusion of hydrogen into helium is producing energy in its core.
C)   Nuclear fission of heavy elements in the central core is releasing energy.
D)   Gravitational potential energy is released as the star slowly contracts.E) C) and D)
F) B) and C)

Question 7

A neutron star is detected from Earth as a pulsar by its regular radio pulses only if Earth lies:

Accepted Answer

A)   in the neutron star's "equator," the plane perpendicular to its spin axis.
B)   within the path of the narrow beam of radiation being generated by the neutron star along its magnetic axis as the star rotates rapidly.
C)   in the plane of the neutron star's magnetic equator, halfway between its magnetic poles.
D)   directly above the rotation axis of the rotating neutron star.E) B) and C)
F) A) and D)

Question 8

A star ascending the red giant branch for the second time in the asymptotic giant branch phase will have:

Accepted Answer

A)   no nuclear reactions in the core, but a helium-fusion shell outside the core, which itself is surrounded by a shell of hydrogen.
B)   no fusion reactions; the star has used up all its nuclear fuel.
C)   hydrogen-fusion reactions occurring in the core.
D)   no nuclear reactions occurring in the core but hydrogen fusion in a shell outside the core.E) A) and B)
F) A) and C)

Question 9

Consider a group of stars with masses up to eight times the mass of the Sun.Stars of which masses undergo a helium flash?

Accepted Answer

A)   less than 0.4 M
B)   0.4 M to 2 M only
C)   2 M to 8 M only
D)   all stars 0.4 M to 8 ME) B) and D)
F) None of the above

Question 10

Supposedly nothing can escape from a black hole,yet astronomers are locating black hole candidates by the X-rays they emit.How can X-rays be coming from a black hole?

Accepted Answer

A)   The X-rays come from a highly compressed region in an accretion disk outside the event horizon of the black hole.
B)   X-rays are not light or matter and can therefore escape from inside the black hole.
C)   If the black hole is rotating, it modifies spacetime around it so much that particles and X-rays are created in the vacuum just outside the event horizon.
D)   The X-rays are produced by vibrations of the black hole itself and therefore do not come from inside the black hole.E) None of the above
F) A) and B)

Question 11

Fred and Joanne both measure the length of a particular spaceship to be 100 m when it is on Earth.Joanne then gets into the spaceship and,after visiting the Moon,hurtles past Earth at a speed close to the speed of light.Fred,still on Earth,measures the length of the moving spaceship to be about 90 m.At the same time,Joanne (using her own meterstick) measures the length of the spaceship to be:

Accepted Answer

A)   about 90 m because of the motion of the spaceship.
B)   100 m because she is "at rest" on the spaceship.
C)   about 110 m because both she and the spaceship are moving.
D)   It is not possible to tell from the information given.E) B) and C)
F) A) and B)

Question 12

Many possible explanations were offered when pulsars were first discovered.Which explanation proved to be CORRECT?

Accepted Answer

A)   alien civilizations
B)   expansion and contraction
C)   small rotating objects
D)   large rotating objectsE) B) and C)
F) A) and D)

Question 13

Thermonuclear reactions release energy because the product (ash) nucleus:

Accepted Answer

A)   contains fewer protons than the original (fuel)  nucleus since these protons have been converted into energy.
B)   is more tightly bound than the original (fuel)  nucleus.
C)   is less tightly bound than the original (fuel)  nucleus.
D)   is moving faster than the original (fuel)  nucleus, and the excess kinetic energy shows up as heat.E) C) and D)
F) B) and C)

Question 14

What is the source of MOST of the heavy elements on Earth and in our own bodies?

Accepted Answer

A)   thermonuclear fusion reactions in the cores of massive stars before the supernova phase
B)   explosive nucleosynthesis during supernova explosions of massive stars
C)   vosmic ray interactions with hydrogen and helium nuclei in interstellar clouds
D)   nuclear reactions during the formation of the universe (the Big Bang) E) A) and C)
F) A) and D)

Question 15

Suppose that a large piece (e.g.,5 solar masses) of purple,magnetized iron is rotating five times per day.If this object were able to collapse gravitationally to form a black hole,which property of the matter inside the black hole could an outside observer actually measure?

Accepted Answer

A)   the rotation
B)   the magnetic field
C)   the color
D)   the compositionE) All of the above
F) A) and B)

Question 16

Suppose you are aboard a spaceship that is passing Earth at 80% of the speed of light.You see a clock on Earth tick off 5 seconds.How much time elapses on your own clock while this is happening?

Accepted Answer

A)   5 seconds-the same as on the ship's clock
B)   more than 5 seconds
C)   more than 5 seconds if you are approaching Earth and less than 5 seconds if you are moving away from Earth
D)   less than 5 secondsE) B) and C)
F) A) and B)

Question 17

A photon escaping from a large mass is gravitationally redshifted.What happens to the color of an object falling toward a black hole (observed from far away) ?

Accepted Answer

A)   The color of the object will be blueshifted.
B)   The color of the object will remain unchanged.
C)   The color of the object will be redshifted because the photons reaching our eyes are escaping the vicinity of the black hole.
D)   As the object accelerates toward the black hole, moving faster and faster, the idea of color ceases to have meaning as the photons shift from visible violet to ultraviolet and then X-rays and gamma rays.E) None of the above
F) A) and C)

Question 18

X-rays that come from the vicinity of a black hole actually originate from:

Accepted Answer

A)   just outside the event horizon, on the accretion disk.
B)   the exact center, or singularity, of the black hole.
C)   relatively far away from the black hole, where matter is quite cool.
D)   well inside the event horizon.E) A) and B)
F) A) and C)

Question 19

How many properties of the matter inside a black hole can be measured from outside the black hole?

Accepted Answer

A)   6
B)   4
C)   3
D)   only 1E) B) and C)
F) All of the above

Question 20

Gas can be pulled off a binary companion by a black hole.The black hole's event horizon is too small to allow all the gas to enter perpendicularly,so it orbits in a ring around the black hole or a neutron star.What is this ring called?

Accepted Answer

A)   a gas ring
B)   a Kerr disk
C)   an accretion disk
D)   an ergoregionE) A) and C)
F) A) and B)

Exam 12: The Deaths and Remnants of Stars

Consider a group of stars with masses up to eight times the mass of the Sun.Stars of which masses will end up as pure helium?

Correct Answer
verified

Thermonuclear reactions release energy because the product (ash) nucleus:

Correct Answer
verified

A star ascending the red giant branch for the second time in the asymptotic giant branch phase will have:

Correct Answer
verified

Correct Answer
verified

X-rays that come from the vicinity of a black hole actually originate from:

Correct Answer
verified

Suppose that a large piece (e.g.,5 solar masses) of purple,magnetized iron is rotating five times per day.If this object were able to collapse gravitationally to form a black hole,which property of the matter inside the black hole could an outside observer actually measure?

Correct Answer
verified

How many properties of the matter inside a black hole can be measured from outside the black hole?

Correct Answer
verified

Many possible explanations were offered when pulsars were first discovered.Which explanation proved to be CORRECT?

Correct Answer
verified

Supposedly nothing can escape from a black hole,yet astronomers are locating black hole candidates by the X-rays they emit.How can X-rays be coming from a black hole?

Correct Answer
verified

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?

Correct Answer
verified

What is the source of MOST of the heavy elements on Earth and in our own bodies?

Correct Answer
verified

What is photodisintegration?

Correct Answer
verified

Gas can be pulled off a binary companion by a black hole.The black hole's event horizon is too small to allow all the gas to enter perpendicularly,so it orbits in a ring around the black hole or a neutron star.What is this ring called?

Correct Answer
verified

Consider a group of stars with masses up to eight times the mass of the Sun.Stars of which masses undergo a helium flash?

Correct Answer
verified

A photon escaping from a large mass is gravitationally redshifted.What happens to the color of an object falling toward a black hole (observed from far away) ?

Correct Answer
verified

In the context of black holes,a singularity is a(n) :

Correct Answer
verified

How much mass are planetary nebulae estimated to return to the interstellar medium each year over the Galaxy as a whole?

Correct Answer
verified

A neutron star is detected from Earth as a pulsar by its regular radio pulses only if Earth lies:

Correct Answer
verified

How does a white dwarf generate its energy?

Correct Answer
verified

Suppose you are aboard a spaceship that is passing Earth at 80% of the speed of light.You see a clock on Earth tick off 5 seconds.How much time elapses on your own clock while this is happening?

Correct Answer
verified

Exam 12: The Deaths and Remnants of Stars

Consider a group of stars with masses up to eight times the mass of the Sun.Stars of which masses will end up as pure helium?

Correct AnswerverifiedShow Answer

Thermonuclear reactions release energy because the product (ash) nucleus:

Correct AnswerverifiedShow Answer

A star ascending the red giant branch for the second time in the asymptotic giant branch phase will have:

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

X-rays that come from the vicinity of a black hole actually originate from:

Correct AnswerverifiedShow Answer

Suppose that a large piece (e.g.,5 solar masses) of purple,magnetized iron is rotating five times per day.If this object were able to collapse gravitationally to form a black hole,which property of the matter inside the black hole could an outside observer actually measure?

Correct AnswerverifiedShow Answer

How many properties of the matter inside a black hole can be measured from outside the black hole?

Correct AnswerverifiedShow Answer

Many possible explanations were offered when pulsars were first discovered.Which explanation proved to be CORRECT?

Correct AnswerverifiedShow Answer

Supposedly nothing can escape from a black hole,yet astronomers are locating black hole candidates by the X-rays they emit.How can X-rays be coming from a black hole?

Correct AnswerverifiedShow Answer

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?

Correct AnswerverifiedShow Answer

What is the source of MOST of the heavy elements on Earth and in our own bodies?

Correct AnswerverifiedShow Answer

What is photodisintegration?

Correct AnswerverifiedShow Answer

Gas can be pulled off a binary companion by a black hole.The black hole's event horizon is too small to allow all the gas to enter perpendicularly,so it orbits in a ring around the black hole or a neutron star.What is this ring called?

Correct AnswerverifiedShow Answer

Consider a group of stars with masses up to eight times the mass of the Sun.Stars of which masses undergo a helium flash?

Correct AnswerverifiedShow Answer

A photon escaping from a large mass is gravitationally redshifted.What happens to the color of an object falling toward a black hole (observed from far away) ?

Correct AnswerverifiedShow Answer

In the context of black holes,a singularity is a(n) :

Correct AnswerverifiedShow Answer

How much mass are planetary nebulae estimated to return to the interstellar medium each year over the Galaxy as a whole?

Correct AnswerverifiedShow Answer

A neutron star is detected from Earth as a pulsar by its regular radio pulses only if Earth lies:

Correct AnswerverifiedShow Answer

How does a white dwarf generate its energy?

Correct AnswerverifiedShow Answer

Suppose you are aboard a spaceship that is passing Earth at 80% of the speed of light.You see a clock on Earth tick off 5 seconds.How much time elapses on your own clock while this is happening?

Correct AnswerverifiedShow Answer

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