Question 1

In a star's evolutionary life,the asymptotic giant branch (AGB) is the:

Accepted Answer

A)   helium core fusion phase.
B)   pre-main-sequence core hydrogen fusion phase.
C)   hydrogen shell fusion phase prior to helium ignition in the core.
D)   helium shell fusion phase.E) A) and B)
F) A) and C)

Question 2

Just before it exploded,the star that became supernova SN 1987A was a(n) :

Accepted Answer

A)   pulsar.
B)   white dwarf.
C)   M2 I supergiant.
D)   B3 I supergiant.E) A) and D)
F) A) and C)

Question 3

Which measurement is the lower limit for a main-sequence star that will eventually form a black hole?

Accepted Answer

A)   50 solar masses
B)   25 solar masses
C)   3 solar masses
D)   1.4 solar massesE) A) and B)
F) All of the above

Question 4

Why does Einstein's theory of special relativity carry the name special?

Accepted Answer

A)   The theory deals only with motion at speeds significantly less than the speed of light.
B)   The theory deals only with objects that are at rest relative to each other.
C)   The theory deals only with gravity, not with other kinds of forces.
D)   The theory deals only with objects moving in a straight line at a constant speed.E) B) and C)
F) A) and D)

Question 5

The Crab Nebula is:

Accepted Answer

A)   a supernova remnant.
B)   a planetary nebula surrounding a hot star.
C)   a cool, gaseous nebula in which stars are forming.
D)   the active nucleus of a nearby spiral galaxy.E) None of the above
F) All of the above

Question 6

What is located in the exact center of a Kerr (rotating) black hole?

Accepted Answer

A)   nothing
B)   the singularity
C)   the event horizon
D)   the ergoregionE) C) and D)
F) B) and D)

Question 7

What is believed to be the solar mass of the black hole candidate at the center of the galaxy M87?

Accepted Answer

A)   3 million
B)   3 billion
C)   300,000
D)   300E) A) and B)
F) A) and C)

Question 8

Carbon fusion in massive stars combines helium and carbon to produce oxygen.Carbon fusion is followed by oxygen fusion in which oxygen is burned to produce sulfur.Why is a higher temperature required for oxygen fusion than for carbon fusion?

Accepted Answer

A)   Because of extensive mass loss between the carbon-fusion and oxygen-fusion stages, higher temperatures are required for nuclear reactions in the relatively rarified stars in which oxygen fusion takes place.
B)   Larger nuclei, like oxygen, have more protons and are therefore repelled more strongly from other nuclei. Thus, faster speeds (at higher temperatures)  are required to bring these nuclei together than are required for smaller nuclei.
C)   Free neutrons are required in greater numbers to enable the oxygen reaction, and higher temperatures are required to produce them.
D)   The enormous neutrino flux in the core of a massive star inhibits nuclear reactions. High temperatures are necessary to force these neutrinos out of the star so nuclear reactions can proceed.E) B) and C)
F) None of the above

Question 9

Which sentence does NOT state a property of neutron stars?

Accepted Answer

A)   Neutron stars rotate from 1 to 30 times per second.
B)   Neutron stars emit relatively narrow beams of light and other radiation.
C)   Neutron stars contain strong gravitational fields but weak magnetic fields.
D)   Neutron stars are composed almost entirely of neutrons.E) A) and C)
F) B) and C)

Question 10

The only physical properties that are necessary to describe a black hole and its interaction with the rest of the universe completely are:

Accepted Answer

A)   total mass, total angular momentum or spin, and temperature.
B)   total mass, chemical or atomic structure of the matter within it, and overall size.
C)   size of the event horizon, strength of its magnetic field, and size of its solid core.
D)   total mass, total electric charge, and total angular momentum or spin.E) A) and B)
F) None of the above

Question 11

You guide your spacecraft into an orbit a few AU from a black hole.You know it is 4 or 5 solar masses,but you want to measure it more precisely.How would you do so?

Accepted Answer

A)   The mass of a black hole cannot be determined precisely because it is impossible to see beyond the event horizon, so your estimate of 4 or 5 solar masses is as good a value as you can hope for.
B)   You can measure the period and the semimajor axis of your orbit and then use Newton's form of Kepler's third law.
C)   You cannot use Newton's form of Kepler's third law. Because of general relativity, you must use a relativistic form of Kepler's third law.
D)   You must move in toward the black hole and mark the distance as you cross the event horizon. From this distance, the mass can be calculated.E) C) and D)
F) B) and D)

Question 12

How was the mass of the candidate black hole at the center of the galaxy M87 estimated?

Accepted Answer

A)   from the amount of mass that is disappearing into it every year
B)   from the periodic shift in the wavelengths of spectral lines from a companion object around which the black hole is orbiting
C)   from observations of the very high orbital speed of objects close to this center
D)   from the intensity of X-rays emitted from it and the frequency of the flickering of the X-ray intensityE) None of the above
F) C) and D)

Question 13

How does a gravitational field affect the passage of time?

Accepted Answer

A)   Gravity has no effect on the passage of time.
B)   Clocks in a gravitational field run slower than clocks farther from the center of the field when viewed by an observer who is also farther from the center of the field.
C)   Gravity makes time stop.
D)   Clocks in a gravitational field run faster than clocks farther from the center of the field when viewed by an observer who is also farther from the center of the field.E) C) and D)
F) A) and B)

Question 14

How did supernova SN 1987A differ from most other observed supernovae?

Accepted Answer

A)   Supernova SN 1987A occurred in an external galaxy, not the Milky Way Galaxy.
B)   Supernova SN 1987A reached a maximum luminosity ten times that of a normal supernova.
C)   Supernova SN 1987A declined in brightness much faster than most supernovae.
D)   Supernova SN 1987A was a blue supergiant when it blew up rather than the usual red supergiant.E) All of the above
F) None of the above

Question 15

The limit to the amount of mass in a neutron star before neutron degeneracy pressure is unable to withstand the force of gravity and the neutron star is crushed out of existence into a black hole is:

Accepted Answer

A)   about 3 solar masses.
B)   20 solar masses.
C)   about 100 solar masses.
D)   1.4 solar masses.E) A) and B)
F) All of the above

Question 16

If we want to measure the mass of a star or a planet we usually rely on the orbital motion of a satellite or binary companion.Which is the basis for a mass measurement of a solitary mass?

Accepted Answer

A)   time dilation
B)   length contraction
C)   gravitational redshift
D)   geodesicsE) A) and B)
F) None of the above

Question 17

By what method can intermediate black holes NOT form?

Accepted Answer

A)   the collapse of a supermassive star
B)   a collision between massive stars
C)   close tidal interactions between stars
D)   mass transfer between two white dwarves in a binary systemE) All of the above
F) C) and D)

Question 18

Which observation has provided the MOST direct evidence that Type II supernovae are caused by the collapse of the core of a massive star?

Accepted Answer

A)   the detection of high-energy X-rays from the Crab supernova remnant
B)   the detection of iron in the Cassiopeia A supernova remnant
C)   the detection of neutrinos from supernova SN 1987A
D)   the discovery of cosmic raysE) B) and C)
F) A) and B)

Question 19

What result might you expect in a binary system containing a white dwarf with a mass of about 1.4 M?

Accepted Answer

A)   a nova
B)   a Type Ia supernova
C)   a Type II supernova
D)   a planetary nebulaE) A) and C)
F) C) and D)

Question 20

During its life,a massive star creates heavier and heavier elements in its core through thermonuclear fusion,leading up to silicon and iron.What is the fate of the iron that is created?

Accepted Answer

A)   The nuclei are split apart by neutron bombardment, creating lighter elements such as carbon, oxygen, and neon.
B)   The iron is locked up inside the star forever.
C)   The iron is destroyed by later thermonuclear fusion reactions in the core that create even heavier elements such as lead, gold, and uranium.
D)   The iron is torn apart by high-energy photons at the end of the star's life.E) B) and D)
F) B) and C)

Exam 12: The Deaths and Remnants of Stars

What is located in the exact center of a Kerr (rotating) black hole?

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Carbon fusion in massive stars combines helium and carbon to produce oxygen.Carbon fusion is followed by oxygen fusion in which oxygen is burned to produce sulfur.Why is a higher temperature required for oxygen fusion than for carbon fusion?

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If we want to measure the mass of a star or a planet we usually rely on the orbital motion of a satellite or binary companion.Which is the basis for a mass measurement of a solitary mass?

Correct AnswerverifiedShow Answer

How did supernova SN 1987A differ from most other observed supernovae?

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What result might you expect in a binary system containing a white dwarf with a mass of about 1.4 M?

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Why does Einstein's theory of special relativity carry the name special?

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Which sentence does NOT state a property of neutron stars?

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Which observation has provided the MOST direct evidence that Type II supernovae are caused by the collapse of the core of a massive star?

Correct AnswerverifiedShow Answer

In a star's evolutionary life,the asymptotic giant branch (AGB) is the:

Correct AnswerverifiedShow Answer

The limit to the amount of mass in a neutron star before neutron degeneracy pressure is unable to withstand the force of gravity and the neutron star is crushed out of existence into a black hole is:

Correct AnswerverifiedShow Answer

The Crab Nebula is:

Correct AnswerverifiedShow Answer

Which measurement is the lower limit for a main-sequence star that will eventually form a black hole?

Correct AnswerverifiedShow Answer

You guide your spacecraft into an orbit a few AU from a black hole.You know it is 4 or 5 solar masses,but you want to measure it more precisely.How would you do so?

Correct AnswerverifiedShow Answer

Just before it exploded,the star that became supernova SN 1987A was a(n) :

Correct AnswerverifiedShow Answer

How was the mass of the candidate black hole at the center of the galaxy M87 estimated?

Correct AnswerverifiedShow Answer

What is believed to be the solar mass of the black hole candidate at the center of the galaxy M87?

Correct AnswerverifiedShow Answer

During its life,a massive star creates heavier and heavier elements in its core through thermonuclear fusion,leading up to silicon and iron.What is the fate of the iron that is created?

Correct AnswerverifiedShow Answer

By what method can intermediate black holes NOT form?

Correct AnswerverifiedShow Answer

How does a gravitational field affect the passage of time?

Correct AnswerverifiedShow Answer

The only physical properties that are necessary to describe a black hole and its interaction with the rest of the universe completely are:

Correct AnswerverifiedShow Answer

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