Question 1

A white dwarf is .

Accepted Answer

A)  an early stage of a neutron star
B)  a brown dwarf that has exhausted its fuel for nuclear fusion
C)  a precursor to a black hole
D)  what most stars become when they die

Question 2

What kind of pressure supports a white dwarf?

Accepted Answer

A)  thermal pressure
B)  neutron degeneracy pressure
C)  radiation pressure
D)  electron degeneracy pressure
E)  all of the above

Question 3

Which of the following observatories is most likely to discover a black hole in a binary system?

Accepted Answer

A)  the Arecibo Radio Observatory
B)  the Hubble Space Telescope
C)  the SOFIA airborne infrared observatory
D)  the Chandra X- Ray Observatory

Question 4

Why does the size of a white dwarf decrease with increasing mass?

Accepted Answer

A more massive white dwarf has a stronger gravitational force that compresses its mass to a greater density. The degeneracy pressure that supports a white dwarf against collapse increases as the density increases, and the balance between degeneracy pressure and gravity is reached such that the a more massive white dwarf is smaller in radius.
Answer Key Testname: C14

Question 5

In which wavelength region(s) would we need to carry out observations in order to study the accretion disk around a white dwarf in a binary system?

Accepted Answer

A)  visible light
B)  ultraviolet light
C)  X- ray light
D)  A and B
E)  B and C

Question 6

Suppose you drop a clock toward a black hole. As you look at the clock from a high orbit, what will you notice?

Accepted Answer

A)  Time on the clock will run slower as it approaches the black hole, and light from the clock will be increasingly redshifted.
B)  Time on the clock will run faster as it approaches the black hole, and light from the clock will be increasingly blueshifted.
C)  The clock will fall faster and faster, reaching the speed of light as it crosses the event horizon.
D)  The clock will fall toward the black hole at a steady rate, so that you'll see it plunge through the event horizon within just a few minutes.

Question 7

There is no upper limit to the mass of a neutron star.

Accepted Answer

A) True 
 B)False

Question 8

Neutron stars are the densest objects that we can directly observe in the universe.

Accepted Answer

A) True 
 B)False

Question 9

A paperclip with the density of a neutron star would weigh (on the Earth)

Accepted Answer

A)  a few tons.
B)  about the same as a regular paperclip.
C)  more than the Moon.
D)  more than the Earth.
E)  more than Mt. Everest.

Question 10

What causes the radio pulses of a pulsar?

Accepted Answer

A)  A black hole near the neutron star absorbs energy and re- emits it as radio waves.
B)  The neutron star undergoes periodic explosions of nuclear fusion that generate radio pulses.
C)  As the neutron star spins, beams of radio radiation sweep through space. If one of the beams crosses the Earth, we observe a pulse.
D)  The neutron star's orbiting companion periodically eclipses the radio waves that the neutron star emits.
E)  The vibration of the neutron star

Question 11

Which of the following best describes what would happen if a 1.5 solar mass neutron star, with a diameter of a few kilometers, were suddenly to appear in your hometown?

Accepted Answer

A)  It would rapidly sink to the center of the Earth.
B)  The entire mass of the Earth would end up as a thin layer, about 1 cm thick, over the surface of the neutron star.
C)  The combined mass of the Earth and the neutron star would cause the neutron star to collapse into a black hole.
D)  It would crash into the Earth, throwing vast amounts of dust into the atmosphere which in turn would cool the Earth. Such a scenario is probably what caused the extinction of the dinosaurs.
E)  It would crash through the Earth, creating a large crater, and exit the Earth on the other side.

Question 12

No visible light can escape a black hole, but things such as gamma rays, X- rays, and neutrinos can.

Accepted Answer

A) True 
 B)False  False

Question 13

A typical white dwarf is .

Accepted Answer

A)  as massive as the Sun but only about as large in size as Earth
B)  as massive as the Sun but only about as large in size as Jupiter
C)  about the same size and mass as the Sun but much hotter
D)  as large in diameter as the Sun but only about as massive as Earth

Question 14

A teaspoonful of white dwarf material on Earth would weigh

Accepted Answer

A)  about the same as the Earth.
B)  about the same as Mt. Everest.
C)  a few grams.
D)  a few pounds.
E)  a few tons.

Question 15

Which of the following statements about electron degeneracy pressure and neutron degeneracy pressure is true?

Accepted Answer

A)  Electron degeneracy pressure is the main source of pressure in white dwarfs, while neutron degeneracy pressure is the main source of pressure in neutron stars.
B)  In a black hole, the pressure coming from neutron degeneracy pressure is slightly greater than that coming from electron degeneracy pressure.
C)  Both electron degeneracy pressure and neutron degeneracy pressure help govern the internal structure of a main- sequence star.
D)  The life of a white dwarf is an ongoing battle between electron degeneracy pressure and neutron degeneracy pressure.

Question 16

Brown dwarfs, white dwarfs, and neutrons stars are all kept from collapsing by degeneracy pressure.

Accepted Answer

A) True 
 B)False  True

Question 17

This figure shows how the luminosity of supernovae change over time. How long does it take a white dwarf supernova to decrease in luminosity by a factor of 100 from its peak?

Accepted Answer

A)  about 200 days
B)  about 100 days
C)  about 300 days
D)  about 25 days

Question 18

The maximum mass for a white dwarf is 1.4 solar masses.

Accepted Answer

A) True 
 B)False

Question 19

The coolest white- dwarf: Surveys have been carried out to identify isolated white- dwarfs throughout the galaxy and its globular clusters. They have been found to span a range of temperatures, with a sharp lower limit of about 3000 K (i.e. many have been found at all temperatures from 10s of thousands of Kelvin down to 3000K, but none cooler). What does this observation reveal about the age of our galaxy?

Accepted Answer

The galaxy has a finite age, when enough...

Question 20

You want to determine whether a mystery object is a neutron star or a white dwarf. Which of the following properties would demonstrate that it is definitely a neutron star?

Accepted Answer

A)  It emits most strongly in visible and ultraviolet light.
B)  Every decade or so, it erupts in a nova explosion.
C)  It is surrounded by a planetary nebula.
D)  It dims and brightens more than twice per second.

Exam 14: The Bizarre Stellar Graveyard

A white dwarf is .

Correct Answer
verified

What kind of pressure supports a white dwarf?

Correct Answer
verified

Which of the following observatories is most likely to discover a black hole in a binary system?

Correct Answer
verified

Why does the size of a white dwarf decrease with increasing mass?

In which wavelength region(s) would we need to carry out observations in order to study the accretion disk around a white dwarf in a binary system?

Correct Answer
verified

Suppose you drop a clock toward a black hole. As you look at the clock from a high orbit, what will you notice?

Correct Answer
verified

There is no upper limit to the mass of a neutron star.

Correct Answer
verified

Neutron stars are the densest objects that we can directly observe in the universe.

Correct Answer
verified

A paperclip with the density of a neutron star would weigh (on the Earth)

Correct Answer
verified

What causes the radio pulses of a pulsar?

Correct Answer
verified

Which of the following best describes what would happen if a 1.5 solar mass neutron star, with a diameter of a few kilometers, were suddenly to appear in your hometown?

Correct Answer
verified

No visible light can escape a black hole, but things such as gamma rays, X- rays, and neutrinos can.

Correct Answer
verified
False

A typical white dwarf is .

Correct Answer
verified

A teaspoonful of white dwarf material on Earth would weigh

Correct Answer
verified

Which of the following statements about electron degeneracy pressure and neutron degeneracy pressure is true?

Correct Answer
verified

Brown dwarfs, white dwarfs, and neutrons stars are all kept from collapsing by degeneracy pressure.

Correct Answer
verified
True

This figure shows how the luminosity of supernovae change over time. How long does it take a white dwarf supernova to decrease in luminosity by a factor of 100 from its peak?

Correct Answer
verified

The maximum mass for a white dwarf is 1.4 solar masses.

Correct Answer
verified

Correct Answer
verified
The galaxy has a finite age, when enough...
View Answer

You want to determine whether a mystery object is a neutron star or a white dwarf. Which of the following properties would demonstrate that it is definitely a neutron star?

Correct Answer
verified

Exam 14: The Bizarre Stellar Graveyard

A white dwarf is .

Correct AnswerverifiedShow Answer

What kind of pressure supports a white dwarf?

Correct AnswerverifiedShow Answer

Which of the following observatories is most likely to discover a black hole in a binary system?

Correct AnswerverifiedShow Answer

Why does the size of a white dwarf decrease with increasing mass?

In which wavelength region(s) would we need to carry out observations in order to study the accretion disk around a white dwarf in a binary system?

Correct AnswerverifiedShow Answer

Suppose you drop a clock toward a black hole. As you look at the clock from a high orbit, what will you notice?

Correct AnswerverifiedShow Answer

There is no upper limit to the mass of a neutron star.

Correct AnswerverifiedShow Answer

Neutron stars are the densest objects that we can directly observe in the universe.

Correct AnswerverifiedShow Answer

A paperclip with the density of a neutron star would weigh (on the Earth)

Correct AnswerverifiedShow Answer

What causes the radio pulses of a pulsar?

Correct AnswerverifiedShow Answer

Which of the following best describes what would happen if a 1.5 solar mass neutron star, with a diameter of a few kilometers, were suddenly to appear in your hometown?

Correct AnswerverifiedShow Answer

No visible light can escape a black hole, but things such as gamma rays, X- rays, and neutrinos can.

Correct AnswerverifiedFalse

A typical white dwarf is .

Correct AnswerverifiedShow Answer

A teaspoonful of white dwarf material on Earth would weigh

Correct AnswerverifiedShow Answer

Which of the following statements about electron degeneracy pressure and neutron degeneracy pressure is true?

Correct AnswerverifiedShow Answer

Brown dwarfs, white dwarfs, and neutrons stars are all kept from collapsing by degeneracy pressure.

Correct AnswerverifiedTrue

This figure shows how the luminosity of supernovae change over time. How long does it take a white dwarf supernova to decrease in luminosity by a factor of 100 from its peak?

Correct AnswerverifiedShow Answer

The maximum mass for a white dwarf is 1.4 solar masses.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedThe galaxy has a finite age, when enough...View AnswerShow Answer

You want to determine whether a mystery object is a neutron star or a white dwarf. Which of the following properties would demonstrate that it is definitely a neutron star?

Correct AnswerverifiedShow Answer

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
verified

Correct Answer
verified

Correct Answer
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Correct Answer
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False

Correct Answer
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Correct Answer
verified

Correct Answer
verified

Correct Answer
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True

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
The galaxy has a finite age, when enough...
View Answer

Correct Answer
verified