Question 1

What observational evidence do we have that black holes exist?

Accepted Answer

An isolated black hole in space will not

Question 2

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. 
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.

Question 3

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. 
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.

Question 4

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 away 
A)  A few kilometers away 
B)  A few solar radii away 
C)  A few astronomical units (AU) away 
D)  A few parsecs away

Question 5

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 6

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

Question 7

How are neutron stars and white dwarfs similar?

Accepted Answer

They are both compact objects,

Question 8

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. 
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.

Question 9

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. 
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.

Question 10

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 nm 
A)  106 nm 
B)  3 nm 
C)  3 × 106 nm 
D)  1 nm 
E)  3 × 1011 nm

Question 11

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. 
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.

Question 12

___ _____ _ 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 wind 
A)  A gravitational blue shift 
B)  The solar wind 
C)  A gravitational redshift 
D)  A X-ray burst 
E)  A pulsar wind

Question 13

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)  3 
A)  0 
B)  1 
C)  2 
D)  3

Question 14

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 15

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. 
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.

Question 16

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

Question 17

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

Accepted Answer

A) True 
 B)False

Question 18

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

Accepted Answer

The principle of conservation of angular

Question 19

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 stars 
A)  black hole 
B)  neutron star 
C)  white dwarf 
D)  main-sequence stars

Question 20

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. 
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.

What observational evidence do we have that black holes exist?

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

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

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

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.

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

How are neutron stars and white dwarfs similar?

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

None of the pulsars emit pulses of visible light because

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.)

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

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

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

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

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

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

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

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

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?

Pulsars cannot be spinning white dwarfs because

Here and Now

A Users Guide to the Sky

Cycles of the Sun and Moon

The Origin of Modern Astronomy

Light and Telescopes

Atoms and Spectra

The Sun

The Family of Stars

The Formation and Structure of Stars

The Deaths of Stars

The Milky Way Galaxy

Galaxies: Normal and Active

Modern Cosmology

Origin of the Solar System and Extrasolar Planets

Earth and Moon: Bases for Comparative Planetology

Mercury, Venus, and Mars

The Outer Solar System

Meteorites, Asteroids, and Comets

Astrobiology: Life on Other Worlds

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Exam 11: Neutron Stars and Black Holes

What observational evidence do we have that black holes exist?

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

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

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

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.

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

How are neutron stars and white dwarfs similar?

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

None of the pulsars emit pulses of visible light because

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.)

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

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

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

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

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

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

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

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

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?

Pulsars cannot be spinning white dwarfs because

Here and Now

A Users Guide to the Sky

Cycles of the Sun and Moon

The Origin of Modern Astronomy

Light and Telescopes

Atoms and Spectra

The Sun

The Family of Stars

The Formation and Structure of Stars

The Deaths of Stars

The Milky Way Galaxy

Galaxies: Normal and Active

Modern Cosmology

Origin of the Solar System and Extrasolar Planets

Earth and Moon: Bases for Comparative Planetology

Mercury, Venus, and Mars

The Outer Solar System

Meteorites, Asteroids, and Comets

Astrobiology: Life on Other Worlds

Filters

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.)

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

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