Question 1

What is the escape velocity from the surface of a neutron star with a mass of 2   and a radius of 10 km?

Accepted Answer

A)  5.3*1016 m/sec 
B)  1.6*108 km/sec 
C)  2.3*108 m/sec 
D)  2.3*108 km/sec 
E)  3.0*108 m/sec 
A)  5.3*1016 m/sec 
B)  1.6*108 km/sec 
C)  2.3*108 m/sec 
D)  2.3*108 km/sec 
E)  3.0*108 m/sec C

Question 2

None of the pulsars emit 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 red shifted. 
D)  pulsars are too far away for the visible light to be bright enough to be detected at Earth. 
E)  The premise is false.A few pulsars are known to 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 red shifted. 
D)  pulsars are too far away for the visible light to be bright enough to be detected at Earth. 
E)  The premise is false.A few pulsars are known to emit visible light pulses. E

Question 3

Rotating black holes are called Kerr black holes.

Accepted Answer

A) True 
 B)False  True

Question 4

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 10x 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 5

Neutron stars have densities roughly the same as that of the atomic nucleus.

Accepted Answer

A) True 
 B)False

Question 6

Neutron stars were first discovered in the 1930s.

Accepted Answer

A) True 
 B)False

Question 7

The search for black holes involves

Accepted Answer

A)  searching for single stars that emit large amounts of x-rays. 
B)  finding x-ray binaries where the compact companion has a mass in excess of 3. 
C)  searching for large spherical regions from which no light is detected. 
D)  looking for pulsars with periods less than one millisecond. 
A)  searching for single stars that emit large amounts of x-rays. 
B)  finding x-ray binaries where the compact companion has a mass in excess of 3. 
C)  searching for large spherical regions from which no light is detected. 
D)  looking for pulsars with periods less than one millisecond.

Question 8

Which of the following can you never know about a black hole?

Accepted Answer

A)  Mass 
B)  Rotation 
C)  Electrical charge 
D)  The material that has fallen in. 
A)  Mass 
B)  Rotation 
C)  Electrical charge 
D)  The material that has fallen in.

Question 9

A(n)____________________ periodically emits large amounts of x-ray radiation as material accretes around a neutron star or black hole.

Accepted Answer

The answer of A(n)____________________ periodically emits large amounts of x-ray...

Question 10

To determine whether the compact object in an x-ray binary is a neutron star or a black hole,we must find the temperature of the compact object.

Accepted Answer

A) True 
 B)False

Question 11

A(n)____________________ is a rapidly spinning neutron star that accelerates charged particles near the poles of its magnetic field.

Accepted Answer

The answer of A(n)____________________ is a rapidly spinning neutron star...

Question 12

As material flows into a black hole

Accepted Answer

A)  the material will experience time dilation. 
B)  the material will become hotter. 
C)  the material will produce an absorption spectrum. 
D)  the material will increase in mass. 
E)  a and b 
A)  the material will experience time dilation. 
B)  the material will become hotter. 
C)  the material will produce an absorption spectrum. 
D)  the material will increase in mass. 
E)  a and b

Question 13

The escape velocity of an object depends on

Accepted Answer

A)  I,II,III,IV,& V 
B)  I & IV 
C)  I,II,III,& V 
D)  I,III,& V 
E)  I & III 
A)  I,II,III,IV,& V 
B)  I & IV 
C)  I,II,III,& V 
D)  I,III,& V 
E)  I & III

Question 14

The event horizon

Accepted Answer

A)  is believed to be a singularity. 
B)  is a crystalline layer. 
C)  has a radius equal to the Schwarzschild radius. 
D)  marks the inner boundary of a planetary nebula. 
E)  is located at the point where synchrotron radiation is created around a pulsar. 
A)  is believed to be a singularity. 
B)  is a crystalline layer. 
C)  has a radius equal to the Schwarzschild radius. 
D)  marks the inner boundary of a planetary nebula. 
E)  is located at the point where synchrotron radiation is created around a pulsar.

Question 15

Glitches are associated with

Accepted Answer

A)  x-ray bursters. 
B)  rapidly rotating black holes. 
C)  the collapse of a white dwarf to form a neutron star. 
D)  changes in the rotation rate of a pulsar. 
E)  planets that orbit pulsars. 
A)  x-ray bursters. 
B)  rapidly rotating black holes. 
C)  the collapse of a white dwarf to form a neutron star. 
D)  changes in the rotation rate of a pulsar. 
E)  planets that orbit pulsars.

Question 16

Although neutron stars are very hot,they are not easy to locate because

Accepted Answer

A)  light does not escape from their event horizon. 
B)  most lie beyond dense dust clouds. 
C)  solid neutron material cannot radiate photons. 
D)  they are only found in other galaxies. 
E)  they have small surface areas. 
A)  light does not escape from their event horizon. 
B)  most lie beyond dense dust clouds. 
C)  solid neutron material cannot radiate photons. 
D)  they are only found in other galaxies. 
E)  they have small surface areas.

Question 17

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 because of the strong magnetic field. 
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 above 
A)  the material will produce synchrotron radiation because of the strong magnetic field. 
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 above

Question 18

A neutron star is expected to spin rapidly because

Accepted Answer

A)  they conserved angular momentum when they collapsed. 
B)  they have high orbital velocities. 
C)  they have high densities. 
D)  they have high temperatures. 
E)  the energy from the supernova explosion that formed them made them spin faster. 
A)  they conserved angular momentum when they collapsed. 
B)  they have high orbital velocities. 
C)  they have high densities. 
D)  they have high temperatures. 
E)  the energy from the supernova explosion that formed them made them spin faster.

Question 19

The figure shows an image of an isolated black hole.A black hole emits...

Accepted Answer

A)  light with wavelengths in the black color region. 
B)  no light from inside the event horizon. 
C)  light which is blueshifted to shorter wavelenghs as it escapes. 
D)  light which is redshifted to shorter wavelengths as it escapes. 
A)  light with wavelengths in the black color region. 
B)  no light from inside the event horizon. 
C)  light which is blueshifted to shorter wavelenghs as it escapes. 
D)  light which is redshifted to shorter wavelengths as it escapes.

Question 20

The ____________________ of a black hole in a binary system can emit X-rays and allow us to detect the presence of the black hole.

Accepted Answer

The answer of The ____________________ of a black hole in...

Exam 14: Neutron Stars and Black Holes

What is the escape velocity from the surface of a neutron star with a mass of 2 and a radius of 10 km?

None of the pulsars emit visible light because

Rotating black holes are called Kerr black holes.

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 10x the mass of the sun.Which is the best choice for these objects?

Neutron stars have densities roughly the same as that of the atomic nucleus.

Neutron stars were first discovered in the 1930s.

The search for black holes involves

Which of the following can you never know about a black hole?

A(n)____________________ periodically emits large amounts of x-ray radiation as material accretes around a neutron star or black hole.

To determine whether the compact object in an x-ray binary is a neutron star or a black hole,we must find the temperature of the compact object.

A(n)____________________ is a rapidly spinning neutron star that accelerates charged particles near the poles of its magnetic field.

As material flows into a black hole

The escape velocity of an object depends on

The event horizon

Glitches are associated with

Although neutron stars are very hot,they are not easy to locate because

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

A neutron star is expected to spin rapidly because

The figure shows an image of an isolated black hole.A black hole emits...

The ____________________ of a black hole in a binary system can emit X-rays and allow us to detect the presence of the black hole.

Here and Now

A Users Guide to the Sky

Cycles of the Moon

The Origin of Modern Astronomy

Gravity

Light and Telescopes

Atoms and Spectra

The Sun

The Family of Stars

The Interstellar Medium

The Formation and Structure of Stars

Stellar Evolution

The Deaths of Stars

The Milky Way Galaxy

Galaxies

Active Galaxies and Supermassive Black Holes

Modern Cosmology

The Origin of the Solar System

Earth: the Standard of Comparative Planetology

The Moon and Mercury: Comparing Airless Worlds

Venus and Mars

Jupiter and Saturn

Uranus,neptune,and the Kuiper Belt

Meteorites,asteroids,and Comets

Astrobiology: Life on Other Worlds

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