Question 1

The Schwartzschild radius for a 12 solar mass star is:

Accepted Answer

A)   4 km.
B)   15 km.
C)   36 km.
D)   100 km.
E)   3000 km.

Question 2

A rapidly rotating compact star that emits a beam of energy like a cosmic lighthouse is usually found by observation at ________ wavelengths.

Accepted Answer

The answer of A rapidly rotating compact star that emits...

Question 3

Mercury's orbital precession is adequately explained by Newton's Law of Gravity.

Accepted Answer

A) True 
 B)False

Question 4

How can a black hole of a few solar masses be detected?

Accepted Answer

Look for a binary system in which one bo...

Question 5

What is Cygnus X-1?

Accepted Answer

A)   the brightest star in the constellation Cygnus
B)   the leading candidate for an observable black hole binary system
C)   the strongest X-ray eclipsing binary system in the sky
D)   a millisecond pulsar with three Earth-like planets around it
E)   the first gamma-ray burster to be spotted in other wavelengths as well

Question 6

All neutron stars must begin as millisecond pulsars just after their supernova creation.

Accepted Answer

A) True 
 B)False

Question 7

A method for identifying a black hole is to:

Accepted Answer

A)   look for voids in the star fields.
B)   look for their effects on nearby companions.
C)   locate a visible star that disappears when the black hole passes in front of it.
D)   search for radio waves from the accretion disk.
E)   search for their pulsar signal.

Question 8

What can we detect from matter that has crossed an event horizon?

Accepted Answer

A)   Gamma-ray bursts
B)   Radio waves if the matter was traveling fast enough
C)   Visible light
D)   X-rays if the matter was dense
E)   Nothing

Question 9

How is the Schwartzschild radius calculated?

Accepted Answer

The Schwartzschild r...

Question 10

If light from a distant star passes close to a massive body,the light beam will:

Accepted Answer

A)   bend towards the star due to gravity.
B)   continue moving in a straight line.
C)   change color to a shorter wavelength.
D)   slow down.
E)   accelerate due to gravity.

Question 11

X-ray bursts and gamma ray bursts have the same distribution pattern in the sky.

Accepted Answer

A) True 
 B)False

Question 12

At the event horizon,time stops.

Accepted Answer

A) True 
 B)False

Question 13

Two important properties of young neutron stars are:

Accepted Answer

A)   extremely slow rotation and a strong magnetic field.
B)   extremely rapid rotation and a weak magnetic field.
C)   extremely rapid rotation and a strong magnetic field.
D)   no rotation and a weak magnetic field.
E)   no rotation and no magnetic field.

Question 14

Which of the following is NOT an argument for Cygnus X-1's being a true black hole?

Accepted Answer

A)   Spectroscopic data suggests hot gas is flowing from the companion B star onto Cygnus X-1.
B)   The mass of the visible B star is even greater than Cygnus X-1, at around 25 solar masses.
C)   Cygnus X-1's mass is estimated to be about 10 solar masses.
D)   X-rays from Cygnus X-1 vary on time scales as short as a millisecond.
E)   X-ray observations around the object support a temperature of several million K.

Question 15

The equivalence principle says that a person in an elevator that is in free fall feels the same acceleration as:

Accepted Answer

A)   a person in an elevator going up with an acceleration of g.
B)   a person in space, far from any gravitational source accelerating at g.
C)   a person in an elevator going down with an acceleration of g.
D)   a person in space, far away from any gravitational source with no acceleration.
E)   a person in orbit of Earth accelerating at g upward.

Question 16

What are the three possible outcomes of stellar evolution? Describe each possibility,differentiating their means of formation and their subsequent properties.Which stars on the Main Sequence are thought to end up in each of these forms?

Accepted Answer

If less than 1.4 solar masses the final ...

Question 17

What are X-ray bursters?

Accepted Answer

A)   They are the central sources of energy for planetary nebulae.
B)   They are very massive stars that explode as supernovae, emitting bursts of X- rays and gamma-rays in the process.
C)   They are rapidly rotating black holes whose precession points their poles toward us on occasion.
D)   They are violent energy sources known to lie at the heart of the Milky Way and similar massive galaxies.
E)   They are neutron stars on which accreted matter builds up, then explodes in a violent nuclear explosion.

Question 18

An observer on a planet sees a spaceship approaching at 0.5c.A beam of light projected by the ship would be measured by this observer to travel at:

Accepted Answer

A)   0.25c.
B)   0.5c.
C)   c.
D)   1.5c.
E)   2.5c.

Question 19

When observing an object,such as a space ship that is moving very quickly relative to you,the length of objects on that object will appear to be:

Accepted Answer

A)   longer than when they are at rest.
B)   the same length as when they are at rest.
C)   shorter than when they are at rest.
D)   narrower than when they are at rest.
E)   wider than when they are at rest.

Question 20

A black hole may be visible because electromagnetic radiation is emitted from a(n)________ surrounding it,heated up enough to emit X-rays.

Accepted Answer

The answer of A black hole may be visible because...

Exam 22: Neutron Stars and Black Holes: Strange States of Matter

Two important properties of young neutron stars are:

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Which of the following is NOT an argument for Cygnus X-1's being a true black hole?

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A method for identifying a black hole is to:

Correct AnswerverifiedShow Answer

If light from a distant star passes close to a massive body,the light beam will:

Correct AnswerverifiedShow Answer

X-ray bursts and gamma ray bursts have the same distribution pattern in the sky.

Correct AnswerverifiedShow Answer

How can a black hole of a few solar masses be detected?

Correct AnswerverifiedLook for a binary system in which one bo...View AnswerShow Answer

What can we detect from matter that has crossed an event horizon?

Correct AnswerverifiedShow Answer

An observer on a planet sees a spaceship approaching at 0.5c.A beam of light projected by the ship would be measured by this observer to travel at:

Correct AnswerverifiedShow Answer

A black hole may be visible because electromagnetic radiation is emitted from a(n)________ surrounding it,heated up enough to emit X-rays.

Correct AnswerverifiedShow Answer

At the event horizon,time stops.

Correct AnswerverifiedShow Answer

Mercury's orbital precession is adequately explained by Newton's Law of Gravity.

Correct AnswerverifiedShow Answer

The equivalence principle says that a person in an elevator that is in free fall feels the same acceleration as:

Correct AnswerverifiedShow Answer

A rapidly rotating compact star that emits a beam of energy like a cosmic lighthouse is usually found by observation at ________ wavelengths.

Correct AnswerverifiedShow Answer

All neutron stars must begin as millisecond pulsars just after their supernova creation.

Correct AnswerverifiedShow Answer

When observing an object,such as a space ship that is moving very quickly relative to you,the length of objects on that object will appear to be:

Correct AnswerverifiedShow Answer

What are the three possible outcomes of stellar evolution? Describe each possibility,differentiating their means of formation and their subsequent properties.Which stars on the Main Sequence are thought to end up in each of these forms?

Correct AnswerverifiedIf less than 1.4 solar masses the final ...View AnswerShow Answer

The Schwartzschild radius for a 12 solar mass star is:

Correct AnswerverifiedShow Answer

What is Cygnus X-1?

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What are X-ray bursters?

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How is the Schwartzschild radius calculated?

Correct AnswerverifiedThe Schwartzschild r...View AnswerShow Answer

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Look for a binary system in which one bo...
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If less than 1.4 solar masses the final ...
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The Schwartzschild r...
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