Question 1

What is an X-ray burster? What causes the X-ray bursts?

Accepted Answer

It is a neutron star in a close binary s

Question 2

The white dwarf that remains when our Sun dies will be mostly made of ________.

Accepted Answer

A)  hydrogen 
B)  helium 
C)  carbon 
D)  neutrons 
A)  hydrogen 
B)  helium 
C)  carbon 
D)  neutrons

Question 3

A typical white dwarf is ________.

Accepted Answer

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

Question 4

Which of the following is closest in size (radius) to a white dwarf?

Accepted Answer

A)  the Earth 
B)  a small city 
C)  a football stadium 
D)  a basketball 
E)  the Sun 
A)  the Earth 
B)  a small city 
C)  a football stadium 
D)  a basketball 
E)  the Sun

Question 5

Which statement concerning black hole masses and Schwarzschild radii is not true?

Accepted Answer

A)  In a binary system with a black hole, the Schwarzschild radius depends on the distance from the black hole to the companion star. 
B)  The more massive the black hole, the larger the Schwarzschild radius. 
C)  Even an object as small as you could become a black hole if there were some way to compress you to a size smaller than your Schwarzschild radius. 
D)  For black holes produced in massive star supernovae, Schwarzschild radii are typically a few to a few tens of kilometers. 
A)  In a binary system with a black hole, the Schwarzschild radius depends on the distance from the black hole to the companion star. 
B)  The more massive the black hole, the larger the Schwarzschild radius. 
C)  Even an object as small as you could become a black hole if there were some way to compress you to a size smaller than your Schwarzschild radius. 
D)  For black holes produced in massive star supernovae, Schwarzschild radii are typically a few to a few tens of kilometers.

Question 6

Imagine that our Sun were magically and suddenly replaced by a black hole of the same mass (1 solar mass). What would happen to Earth in its orbit?

Accepted Answer

A)  Earth would almost instantly be sucked into oblivion in the black hole. 
B)  Earth would orbit faster, but at the same distance. 
C)  Earth would slowly spiral inward until it settled into an orbit about the size of Mercury's current orbit. 
D)  Nothing-Earth's orbit would remain the same. 
A)  Earth would almost instantly be sucked into oblivion in the black hole. 
B)  Earth would orbit faster, but at the same distance. 
C)  Earth would slowly spiral inward until it settled into an orbit about the size of Mercury's current orbit. 
D)  Nothing-Earth's orbit would remain the same.

Question 7

Which stars are more common?

Accepted Answer

A)  Neutron stars 
B)  White dwarfs 
C)  White dwarfs and neutron stars are about equally common. 
D)  Neutron stars and black holes are about equally common. 
E)  Black holes 
A)  Neutron stars 
B)  White dwarfs 
C)  White dwarfs and neutron stars are about equally common. 
D)  Neutron stars and black holes are about equally common. 
E)  Black holes

Question 8

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

Accepted Answer

A) True 
 B)False

Question 9

Will our Sun ever undergo a white dwarf supernova explosion? Why or why not?

Accepted Answer

A)  No, because it is not orbited by another star. 
B)  Yes, right at the end of its double-shell burning stage of life. 
C)  Yes, about a million years after it becomes a white dwarf. 
D)  No, because the Sun's core will never be hot enough to fuse carbon and other heavier elements into iron. 
A)  No, because it is not orbited by another star. 
B)  Yes, right at the end of its double-shell burning stage of life. 
C)  Yes, about a million years after it becomes a white dwarf. 
D)  No, because the Sun's core will never be hot enough to fuse carbon and other heavier elements into iron.

Question 10

How does a black hole form from a massive star?

Accepted Answer

A)  During a supernova, if a star is massive enough for its gravity to overcome neutron degeneracy pressure in the core, the core will collapse to a black hole. 
B)  Any star that is more massive than 8 solar masses will undergo a supernova explosion and leave behind a black hole remnant. 
C)  If enough mass is accreted by a white dwarf star that it exceeds the 1.4 solar mass limit, it will undergo a supernova explosion and leave behind a black-hole remnant. 
D)  If enough mass is accreted by a neutron star, it will undergo a supernova explosion and leave behind a black-hole remnant. 
E)  A black hole forms when two massive main-sequence stars collide. 
A)  During a supernova, if a star is massive enough for its gravity to overcome neutron degeneracy pressure in the core, the core will collapse to a black hole. 
B)  Any star that is more massive than 8 solar masses will undergo a supernova explosion and leave behind a black hole remnant. 
C)  If enough mass is accreted by a white dwarf star that it exceeds the 1.4 solar mass limit, it will undergo a supernova explosion and leave behind a black-hole remnant. 
D)  If enough mass is accreted by a neutron star, it will undergo a supernova explosion and leave behind a black-hole remnant. 
E)  A black hole forms when two massive main-sequence stars collide.

Question 11

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

Accepted Answer

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

Question 12

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

Accepted Answer

A) True 
 B)False

Question 13

Briefly describe how a nova event occurs.

Accepted Answer

A white dwarf in a close binary system a

Question 14

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

Question 15

You are studying a mystery companion to an evolved star, with mass transfer happening. Which of the following properties suggests that the companion is definitely a black hole?

Accepted Answer

A)  The mystery companion has an X-ray emitting accretion disk. 
B)  The mystery companion has a mass of over 1.4 solar masses. 
C)  The mystery companion gives off periodic X-ray bursts. 
D)  The mystery companion has a mass of over 3 solar masses. 
A)  The mystery companion has an X-ray emitting accretion disk. 
B)  The mystery companion has a mass of over 1.4 solar masses. 
C)  The mystery companion gives off periodic X-ray bursts. 
D)  The mystery companion has a mass of over 3 solar masses.

Question 16

Studying the Singularity: The singularity at the center of a black hole is predicted to be a region of zero volume and infinite density that contains all of the black hole's mass. It is a point at which all currently known physical laws break down. Yet in a black hole, this "terrible point" is hidden from view behind an event horizon that prevents any knowledge about the singularity reaching the outside universe. Astronomers continue to spend considerable effort trying to understand the nature of these singularities, objects for which observational input, it would seem, will be forever lacking? Are these astronomers practicing science? Argue both yes and no. Which do you find convincing?

Accepted Answer

Yes, astronomers studying the nature of

Question 17

What is the ultimate fate of an isolated pulsar?

Accepted Answer

A)  It will spin ever faster, becoming a millisecond pulsar. 
B)  As gravity overwhelms the neutron degeneracy pressure, it will explode as a supernova. 
C)  As gravity overwhelms the neutron degeneracy pressure, it will become a white dwarf. 
D)  It will spin ever slower, the magnetic field will weaken, and it will become invisible. 
E)  The neutron degeneracy pressure will eventually overwhelm gravity and the pulsar will slowly evaporate. 
A)  It will spin ever faster, becoming a millisecond pulsar. 
B)  As gravity overwhelms the neutron degeneracy pressure, it will explode as a supernova. 
C)  As gravity overwhelms the neutron degeneracy pressure, it will become a white dwarf. 
D)  It will spin ever slower, the magnetic field will weaken, and it will become invisible. 
E)  The neutron degeneracy pressure will eventually overwhelm gravity and the pulsar will slowly evaporate.

Question 18

Our Sun will likely undergo a nova event in about 5 billion years.

Accepted Answer

A) True 
 B)False

Question 19

What do we mean by the event horizon of a black hole?

Accepted Answer

A)  It is the point beyond which neither light nor anything else can escape. 
B)  It is the very center of the black hole. 
C)  It is the distance from the black hole at which stable orbits are possible. 
D)  It is the place where X-rays are emitted from black holes. 
A)  It is the point beyond which neither light nor anything else can escape. 
B)  It is the very center of the black hole. 
C)  It is the distance from the black hole at which stable orbits are possible. 
D)  It is the place where X-rays are emitted from black holes.

Question 20

Why would the earth's orbit be unaffected were the Sun to suddenly become a black hole?

Accepted Answer

The earth's orbit (and those of the othe

What is an X-ray burster? What causes the X-ray bursts?

The white dwarf that remains when our Sun dies will be mostly made of ________.

A typical white dwarf is ________.

Which of the following is closest in size (radius) to a white dwarf?

Which statement concerning black hole masses and Schwarzschild radii is not true?

Imagine that our Sun were magically and suddenly replaced by a black hole of the same mass (1 solar mass). What would happen to Earth in its orbit?

Which stars are more common?

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

Will our Sun ever undergo a white dwarf supernova explosion? Why or why not?

How does a black hole form from a massive star?

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

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

Briefly describe how a nova event occurs.

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

You are studying a mystery companion to an evolved star, with mass transfer happening. Which of the following properties suggests that the companion is definitely a black hole?

What is the ultimate fate of an isolated pulsar?

Our Sun will likely undergo a nova event in about 5 billion years.

What do we mean by the event horizon of a black hole?

Why would the earth's orbit be unaffected were the Sun to suddenly become a black hole?

Our Place in the Universe

Discovering the Universe for Yourself

The Science of Astronomy

Making Sense of the Universe: Understanding Motion, Energy, and Gravity

Light: the Cosmic Messenger

Formation of Planetary Systems: Our Solar System and Beyond

Earth and the Terrestrial Worlds

Jovian Planet Systems

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Our Star

Surveying the Stars

Star Stuff

Our Galaxy

Galaxies and the Foundation of Modern Cosmology

Dark Matter, Dark Energy, and the Fate of the Universe

The Beginning of Time

Life in the Universe

Filters

Exam 13: Bizarre Stellar Graveyard

What is an X-ray burster? What causes the X-ray bursts?

The white dwarf that remains when our Sun dies will be mostly made of ________.

A typical white dwarf is ________.

Which of the following is closest in size (radius) to a white dwarf?

Which statement concerning black hole masses and Schwarzschild radii is not true?

Imagine that our Sun were magically and suddenly replaced by a black hole of the same mass (1 solar mass). What would happen to Earth in its orbit?

Which stars are more common?

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

Will our Sun ever undergo a white dwarf supernova explosion? Why or why not?

How does a black hole form from a massive star?

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

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

Briefly describe how a nova event occurs.

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

You are studying a mystery companion to an evolved star, with mass transfer happening. Which of the following properties suggests that the companion is definitely a black hole?

What is the ultimate fate of an isolated pulsar?

Our Sun will likely undergo a nova event in about 5 billion years.

What do we mean by the event horizon of a black hole?

Why would the earth's orbit be unaffected were the Sun to suddenly become a black hole?

Our Place in the Universe

Discovering the Universe for Yourself

The Science of Astronomy

Making Sense of the Universe: Understanding Motion, Energy, and Gravity

Light: the Cosmic Messenger

Formation of Planetary Systems: Our Solar System and Beyond

Earth and the Terrestrial Worlds

Jovian Planet Systems

Asteroids, Comets, and Dwarf Planets: Their Nature, Orbits, and Impacts

Our Star

Surveying the Stars

Star Stuff

Our Galaxy

Galaxies and the Foundation of Modern Cosmology

Dark Matter, Dark Energy, and the Fate of the Universe

The Beginning of Time

Life in the Universe

Filters