Question 1

Unseen objects in our galaxy have been found by the bending effect they have on more distant stars' light passing near them. These small objects that don't emit light are calculated to have masses of about 10 × the mass of the Sun. Which is the best choice for these objects?

Accepted Answer

A)   black hole
B)   neutron star
C)   white dwarf
D)   main-sequence starsE) None of the above
F) B) and C)

Question 2

What happens when a core's mass exceeds 3 solar masses and its density exceeds that which electron degeneracy pressure can support?

Accepted Answer

A)   The core collapses into a black hole.
B)   The core collapses into a neutron star.
C)   The core collapses into a white dwarf.
D)   The core collapses into a neutron star or a black hole.E) B) and D)
F) All of the above

Question 3

If the inner accretion disk around a black hole has a temperature of 106 K, at what wavelength will it radiate the most energy? ( Hint : From Wien's law, λ T =3,000,000 where λ is in nm and T is in K.)

Accepted Answer

A)   106 nm
B)   3 nm
C)   3 × 106 nm
D)   1 nm
E)   3 × 1011 nmF) B) and E)
G) None of the above

Question 4

The material that accretes onto a neutron star or black hole is expected to emit X-rays because

Accepted Answer

A)   the material will produce synchrotron radiation.
B)   hydrogen nuclei begin to fuse and emit high-energy photons.
C)   the material will become hot enough that it will radiate most strongly at X-ray wavelengths.
D)   as the material slows down it converts thermal energy to gravitational potential energy.
E)   None of the other choices are correct.F) B) and E)
G) C) and D)

Question 5

What observational evidence do we have that black holes exist?

Accepted Answer

An isolated black hole in space will not...

Question 6

Using the above graph of modulated light from a pulsar, how many planets can you determine to be in this system?

Accepted Answer

A)   0
B)   1
C)   2
D)   3E) All of the above
F) A) and B)

Question 7

For a point mass equal to that of the Sun, how far does the Schwarzschild radius extend from its center?

Accepted Answer

A)   A few kilometers away
B)   A few solar radii away
C)   A few astronomical units (AU)  away
D)   A few parsecs awayE) All of the above
F) None of the above

Question 8

In the lighthouse model shown above, the light bulb represents the neutron star.

Accepted Answer

A) True 
 B)False

Question 9

An isolated black hole in space would be difficult to detect because

Accepted Answer

A)   there would be no light source nearby.
B)   it would not be rotating rapidly.
C)   it would be stationary.
D)   very little matter would be falling into it.
E)   there would be very few stars behind it whose light the black hole could block out.F) C) and D)
G) C) and E)

Question 10

Why does our theory predict that neutron stars will spin rapidly?

Accepted Answer

The principle of conservation of angular...

Question 11

___ _____ _ occurs when light travels out of a gravitational field, loses energy, and its wavelength grows longer.

Accepted Answer

A)   A gravitational blue shift
B)   The solar wind
C)   A gravitational redshift
D)   A X-ray burst
E)   A pulsar windF) C) and E)
G) B) and E)

Question 12

The stability of a neutron star is expected only if a neutron star is a ____________.

Accepted Answer

A)   solid
B)   fluid
C)   gas
D)   All of the other choices are correct.E) B) and C)
F) A) and C)

Question 13

Pulsars cannot be spinning white dwarfs because

Accepted Answer

A)   white dwarfs are not that common.
B)   white dwarfs are not dense enough.
C)   white dwarfs do not have magnetic fields.
D)   a white dwarf spinning that fast would fly apart.
E)   All of the other choices are correct.F) A) and E)
G) All of the above

Question 14

Which of the following objects is considered to possibly contain a black hole?

Accepted Answer

A)   the central star of the Crab nebula
B)   the Orion nebula.
C)   LMC X-3
D)   Algol
E)   PSR 1257+12F) D) and E)
G) B) and C)

Question 15

How are neutron stars and white dwarfs similar?

Accepted Answer

They are both compact objects,...

Question 16

To tell the difference between a neutron star and a black hole in an X-ray binary, we must find the temperature of the object.

Accepted Answer

A) True 
 B)False

Question 17

A star on the main sequence has 7 solar masses. The star will evolve into a _____ _______ and its core will be supported by ___ _____ ______.

Accepted Answer

A)   white dwarf, electron degeneracy pressure
B)   neutron star, neutron degeneracy pressure
C)   black hole, no pressure (i.e., it will not be supported) 
D)   white dwarf, neutron star, or black hole; electron degeneracy, neutron degeneracy, and no pressure, respectively.E) None of the above
F) A) and C)

Question 18

Why might we suspect that a black hole in a binary system could emit X-rays?

Accepted Answer

If matter flows into a black h...

Question 19

None of the pulsars emit pulses of visible light because

Accepted Answer

A)   pulsars are too hot to emit visible light.
B)   pulsars contain black holes that won't let visible light escape.
C)   the gravitational field of a pulsar is so great that the visible light emitted is redshifted.
D)   pulsars are too far away for the visible light to be bright enough to be detected at Earth.
E)   A few pulsars do emit visible light pulses.F) C) and E)
G) C) and D)

Question 20

Although neutron stars are very hot, they are faint and not easy to see at visual wavelengths because

Accepted Answer

A)   light does not escape from their event horizon.
B)   most lie beyond dense dust clouds.
C)   they have only a small surface area from which to emit.
D)   the peak of their thermal emission is at much shorter wavelengths than visual.
E)   they have only a small surface area from which to emit and the peak of their thermal emission is at much shorter wavelengths than visual.F) All of the above
G) C) and D)

Exam 11: Neutron Stars and Black Holes

A star on the main sequence has 7 solar masses. The star will evolve into a _____ _______ and its core will be supported by ___ _____ ______.

Correct AnswerverifiedShow Answer

Using the above graph of modulated light from a pulsar, how many planets can you determine to be in this system?

Correct AnswerverifiedShow Answer

For a point mass equal to that of the Sun, how far does the Schwarzschild radius extend from its center?

Correct AnswerverifiedShow Answer

To tell the difference between a neutron star and a black hole in an X-ray binary, we must find the temperature of the object.

Correct AnswerverifiedShow Answer

How are neutron stars and white dwarfs similar?

Correct AnswerverifiedThey are both compact objects,...View AnswerShow Answer

Why might we suspect that a black hole in a binary system could emit X-rays?

Correct AnswerverifiedIf matter flows into a black h...View AnswerShow Answer

Which of the following objects is considered to possibly contain a black hole?

Correct AnswerverifiedShow Answer

An isolated black hole in space would be difficult to detect because

Correct AnswerverifiedShow Answer

What observational evidence do we have that black holes exist?

Correct AnswerverifiedAn isolated black hole in space will not...View AnswerShow Answer

The stability of a neutron star is expected only if a neutron star is a ____________.

Correct AnswerverifiedShow Answer

If the inner accretion disk around a black hole has a temperature of 106 K, at what wavelength will it radiate the most energy? ( Hint : From Wien's law, λ T =3,000,000 where λ is in nm and T is in K.)

Correct AnswerverifiedShow Answer

In the lighthouse model shown above, the light bulb represents the neutron star.

Correct AnswerverifiedShow Answer

None of the pulsars emit pulses of visible light because

Correct AnswerverifiedShow Answer

What happens when a core's mass exceeds 3 solar masses and its density exceeds that which electron degeneracy pressure can support?

Correct AnswerverifiedShow Answer

The material that accretes onto a neutron star or black hole is expected to emit X-rays because

Correct AnswerverifiedShow Answer

Although neutron stars are very hot, they are faint and not easy to see at visual wavelengths because

Correct AnswerverifiedShow Answer

Pulsars cannot be spinning white dwarfs because

Correct AnswerverifiedShow Answer

Unseen objects in our galaxy have been found by the bending effect they have on more distant stars' light passing near them. These small objects that don't emit light are calculated to have masses of about 10 × the mass of the Sun. Which is the best choice for these objects?

Correct AnswerverifiedShow Answer

Why does our theory predict that neutron stars will spin rapidly?

Correct AnswerverifiedThe principle of conservation of angular...View AnswerShow Answer

___ _____ _ occurs when light travels out of a gravitational field, loses energy, and its wavelength grows longer.

Correct AnswerverifiedShow Answer

A star on the main sequence has 7 solar masses. The star will evolve into a _ _ and its core will be supported by _ _ __.

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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They are both compact objects,...
View Answer

Correct Answer
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If matter flows into a black h...
View Answer

Correct Answer
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Correct Answer
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Correct Answer
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An isolated black hole in space will not...
View Answer

Correct Answer
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If the inner accretion disk around a black hole has a temperature of 10⁶ K, at what wavelength will it radiate the most energy? ( Hint : From Wien's law, λ T =3,000,000 where λ is in nm and T is in K.)

Correct Answer
verified

Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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Correct Answer
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The principle of conservation of angular...
View Answer

_ ___ _ occurs when light travels out of a gravitational field, loses energy, and its wavelength grows longer.

Correct Answer
verified