Question 1

Which of the following objects does NOT represent the endpoint of a star's evolutionary life?

Accepted Answer

A) black hole 
B) neutron star 
C) red giant 
D) supernova 
A) black hole 
B) neutron star 
C) red giant 
D) supernova C

Question 2

The Schwarzschild radius of a black hole is the distance from the singularity (center) to the:

Accepted Answer

A) point where the gravitational field becomes zero. 
B) event horizon, from which light cannot escape. 
C) outside radius of the massive solid body forming the black hole. 
D) accretion disk, from which x rays originate and from which light can still escape. 
A) point where the gravitational field becomes zero. 
B) event horizon, from which light cannot escape. 
C) outside radius of the massive solid body forming the black hole. 
D) accretion disk, from which x rays originate and from which light can still escape. B

Question 3

The radius of the event horizon of a black hole is directly proportional to the mass of the black hole. What is the constant of proportionality?

Accepted Answer

A) 3 m per solar mass 
B) 30 m per solar mass 
C) 3.0 km per solar mass 
D) 30 km per solar mass 
A) 3 m per solar mass 
B) 30 m per solar mass 
C) 3.0 km per solar mass 
D) 30 km per solar mass C

Question 4

Suppose you are in the Space Shuttle in orbit around Earth at a speed of 7 km/s, and at some particular time your direction of travel is straight toward the Sun. The speed of light in a vacuum is 300,000 km/s. What speed will you measure for the light from the Sun?

Accepted Answer

A) 300,000 km/s 
B) 300,014 km/s because your speed is added to that of the light and relativistic contraction has shortened your reference meter sticks 
C) 299,993 km/s because relativistic contraction has shortened all distances, including your reference meter sticks 
D) 300,007 km/s because your speed is added to that of the light 
A) 300,000 km/s 
B) 300,014 km/s because your speed is added to that of the light and relativistic contraction has shortened your reference meter sticks 
C) 299,993 km/s because relativistic contraction has shortened all distances, including your reference meter sticks 
D) 300,007 km/s because your speed is added to that of the light

Question 5

You are flying your spacecraft on a parallel course with another spacecraft and at the same speed. You are both moving past Earth at an appreciable fraction of the speed of light. Which one of the following statements correctly describes the relationship between your clock and the clock in the other spacecraft?

Accepted Answer

A) You will see the clock in the other spacecraft running slow compared to yours. 
B) You will see the clock in the other spacecraft running at the same rate as yours. 
C) A person in the other spacecraft will see his own clock running slow compared to yours. 
D) A person in the other spacecraft will see her own clock running fast compared to yours. 
A) You will see the clock in the other spacecraft running slow compared to yours. 
B) You will see the clock in the other spacecraft running at the same rate as yours. 
C) A person in the other spacecraft will see his own clock running slow compared to yours. 
D) A person in the other spacecraft will see her own clock running fast compared to yours.

Question 6

During a stop on Jupiter's satellite Europa to investigate a possible liquid ocean under the ice, you spot a spaceship passing Europa at 97% of the speed of light. While you see 2 s tick past on the spaceship's clock, how much time ticks by on your own clock?

Accepted Answer

A) 8.2 s. 
B) 33.8 s. 
C) 0.12 s. 
D) 0.48 s. 
A) 8.2 s. 
B) 33.8 s. 
C) 0.12 s. 
D) 0.48 s.

Question 7

One of the best candidates for a black hole in a binary star system at the present time, based on the accuracy of measuring its mass, is:

Accepted Answer

A) V404 Cygni. 
B) LMC X-3. 
C) Cygnus X-1. 
D) HDE 226868. 
A) V404 Cygni. 
B) LMC X-3. 
C) Cygnus X-1. 
D) HDE 226868.

Question 8

The Crab Nebula (M1) is:

Accepted Answer

A) a supernova remnant. 
B) an H II region. 
C) a newly forming star. 
D) a black hole. 
A) a supernova remnant. 
B) an H II region. 
C) a newly forming star. 
D) a black hole.

Question 9

What is the correct explanation of the bending of a beam of light as it passes close to a massive object like the Sun?

Accepted Answer

A) The gravitational field interacts with the electromagnetic field of the photons to bend the light. 
B) It is traveling across and must follow the curved space surrounding a massive object. 
C) The gravitational field of the massive object changes the refractive index of the nearby space, leading to bending of the light. 
D) The photons of light are attracted by the gravitational field of the massive object. 
A) The gravitational field interacts with the electromagnetic field of the photons to bend the light. 
B) It is traveling across and must follow the curved space surrounding a massive object. 
C) The gravitational field of the massive object changes the refractive index of the nearby space, leading to bending of the light. 
D) The photons of light are attracted by the gravitational field of the massive object.

Question 10

What is believed to be the mass of the black hole candidate at the center of the galaxy NGC 4261?

Accepted Answer

A) 120 Mε 
B) 120,000 Mε ​ 
C) 1.2 million Mε 
D) 1.2 billion Mε 
A) 120 Mε 
B) 120,000 Mε ​ 
C) 1.2 million Mε 
D) 1.2 billion Mε

Question 11

The difference between a nova and an x-ray burst is that a nova involves:

Accepted Answer

A) an explosion on the surface of a neutron star, whereas an x-ray burst involves an explosion on the surface of a white dwarf. 
B) an explosion on the surface of a neutron star, whereas an x-ray burst involves the complete collapse of a neutron star to form a black hole. 
C) an explosion on the surface of a white dwarf, whereas an x-ray burst involves an explosion on the surface of a neutron star. 
D) the complete explosive destruction of a white dwarf, whereas an x-ray burst involves an explosion on the surface of the white dwarf. 
A) an explosion on the surface of a neutron star, whereas an x-ray burst involves an explosion on the surface of a white dwarf. 
B) an explosion on the surface of a neutron star, whereas an x-ray burst involves the complete collapse of a neutron star to form a black hole. 
C) an explosion on the surface of a white dwarf, whereas an x-ray burst involves an explosion on the surface of a neutron star. 
D) the complete explosive destruction of a white dwarf, whereas an x-ray burst involves an explosion on the surface of the white dwarf.

Question 12

Clock A sits on the surface of a neutron star, clock B sits on Earth's surface, and clock C rests beside me in space, far from any masses. The clocks are synchronized and all read 12:00 P.M. Ignore the delay caused by light travel time in this question. When clock C reads 1:00 P.M.:

Accepted Answer

A)  clocks A and B will show times between 12:00 P.M. and 1:00 P.M., with A earlier than B. 
B)  clocks A and B will show times between 12:00 P.M. and 1:00 P.M., with B earlier than A. 
C)  clocks A and B will show times later than 1:00 P.M., with A earlier than B. 
D)  clocks A and B will show times later than 1:00 P.M., with B earlier than A. 
A)  clocks A and B will show times between 12:00 P.M. and 1:00 P.M., with A earlier than B. 
B)  clocks A and B will show times between 12:00 P.M. and 1:00 P.M., with B earlier than A. 
C)  clocks A and B will show times later than 1:00 P.M., with A earlier than B. 
D)  clocks A and B will show times later than 1:00 P.M., with B earlier than A.

Question 13

One consequence of the no-hair theorem ("Black holes have no hair") is that:

Accepted Answer

A) matter that falls into a black hole does not retain any measurable properties at all, when observed by an outside observer. 
B) matter that falls into a black hole retains no properties except its mass, as measured by an outside observer. 
C) certain kinds and shapes of matter (i.e., long strings) cannot fall into a black hole. 
D) matter that falls into a black hole does not retain any properties except its mass, spin, and electric charge, as measured by an outside observer. 
A) matter that falls into a black hole does not retain any measurable properties at all, when observed by an outside observer. 
B) matter that falls into a black hole retains no properties except its mass, as measured by an outside observer. 
C) certain kinds and shapes of matter (i.e., long strings) cannot fall into a black hole. 
D) matter that falls into a black hole does not retain any properties except its mass, spin, and electric charge, as measured by an outside observer.

Question 14

Theoretically, the mass of a black hole:

Accepted Answer

A) must be at least 106 Mε. 
B) must be at least 10 Mε. 
C) must be at least 1.4 Mε. 
D) can have any mass. 
A) must be at least 106 Mε. 
B) must be at least 10 Mε. 
C) must be at least 1.4 Mε. 
D) can have any mass.

Question 15

What is a collapsar?

Accepted Answer

A) the name given to any massive star that collapses to form a white dwarf, neutron star, or black hole 
B) a system in which a very massive star collapses to form a black hole surrounded by an accretion disk and jets that beam intense gamma-ray radiation 
C) any gamma-ray burster 
D) the bright flash of light that signals the merger of a black hole and its companion star 
A) the name given to any massive star that collapses to form a white dwarf, neutron star, or black hole 
B) a system in which a very massive star collapses to form a black hole surrounded by an accretion disk and jets that beam intense gamma-ray radiation 
C) any gamma-ray burster 
D) the bright flash of light that signals the merger of a black hole and its companion star

Question 16

How might Tycho's supernova of 1572 have been produced without leaving behind a pulsar?

Accepted Answer

A) Supernovae prior to 1967 did not produce pulsars. 
B) It was a Type Ia supernova. 
C) Any neutron star that may have formed is still hidden in debris and is not yet visible. 
D) It was a Type II supernova. 
A) Supernovae prior to 1967 did not produce pulsars. 
B) It was a Type Ia supernova. 
C) Any neutron star that may have formed is still hidden in debris and is not yet visible. 
D) It was a Type II supernova.

Question 17

The only parts of a nonrotating black hole that are necessary for its complete description are:

Accepted Answer

A) the escape velocity of matter and the diameter of its core. 
B) its center, or singularity, and its "surface," or event horizon. 
C) the gravitational field and the curvature of space at its center. 
D) its semimajor axis and its orbital eccentricity. 
A) the escape velocity of matter and the diameter of its core. 
B) its center, or singularity, and its "surface," or event horizon. 
C) the gravitational field and the curvature of space at its center. 
D) its semimajor axis and its orbital eccentricity.

Question 18

How much mass is lost when two 1-Mε neutron stars merge?

Accepted Answer

A) less than 0.5% 
B) about 1% 
C) about 5% 
D) more than 10% 
A) less than 0.5% 
B) about 1% 
C) about 5% 
D) more than 10%

Question 19

Take two identical, nonrotating, 5-Mε black holes and place them side by side. Add 1 Mε of neutrons to the left-hand one and 1 Mε of protons to the right-hand one (without changing the rotation of the black holes). Afterward, how do these two black holes differ?

Accepted Answer

A) They will not differ at all. 
B) The left-hand one has a stronger gravitational field because a neutron is heavier than a proton. 
C) The light particles, electrons and neutrinos, from the decay of the neutrons into protons escape from the left-hand one. 
D) The left-hand one is electrically neutral and the right-hand one will have an enormous electric charge. 
A) They will not differ at all. 
B) The left-hand one has a stronger gravitational field because a neutron is heavier than a proton. 
C) The light particles, electrons and neutrinos, from the decay of the neutrons into protons escape from the left-hand one. 
D) The left-hand one is electrically neutral and the right-hand one will have an enormous electric charge.

Question 20

The mass of the candidate black hole at the center of the galaxy NGC 4261 was estimated from the:

Accepted Answer

A) application of Kepler's laws to the orbital speed of objects close to this center. 
B) intensity of x rays from it and the speed at which the x rays flicker. 
C) amount of mass that is disappearing into it per year. 
D) periodic shift in the wavelengths of spectral lines from a companion object around which the black hole is orbiting. 
A) application of Kepler's laws to the orbital speed of objects close to this center. 
B) intensity of x rays from it and the speed at which the x rays flicker. 
C) amount of mass that is disappearing into it per year. 
D) periodic shift in the wavelengths of spectral lines from a companion object around which the black hole is orbiting.

Exam 21: Stellar Remnants: Neutron Stars and Black Holes

Which of the following objects does NOT represent the endpoint of a star's evolutionary life?

The Schwarzschild radius of a black hole is the distance from the singularity (center) to the:

The radius of the event horizon of a black hole is directly proportional to the mass of the black hole. What is the constant of proportionality?

Suppose you are in the Space Shuttle in orbit around Earth at a speed of 7 km/s, and at some particular time your direction of travel is straight toward the Sun. The speed of light in a vacuum is 300,000 km/s. What speed will you measure for the light from the Sun?

During a stop on Jupiter's satellite Europa to investigate a possible liquid ocean under the ice, you spot a spaceship passing Europa at 97% of the speed of light. While you see 2 s tick past on the spaceship's clock, how much time ticks by on your own clock?

One of the best candidates for a black hole in a binary star system at the present time, based on the accuracy of measuring its mass, is:

The Crab Nebula (M1) is:

What is the correct explanation of the bending of a beam of light as it passes close to a massive object like the Sun?

What is believed to be the mass of the black hole candidate at the center of the galaxy NGC 4261?

The difference between a nova and an x-ray burst is that a nova involves:

Clock A sits on the surface of a neutron star, clock B sits on Earth's surface, and clock C rests beside me in space, far from any masses. The clocks are synchronized and all read 12:00 P.M. Ignore the delay caused by light travel time in this question. When clock C reads 1:00 P.M.:

One consequence of the no-hair theorem ("Black holes have no hair") is that:

Theoretically, the mass of a black hole:

What is a collapsar?

How might Tycho's supernova of 1572 have been produced without leaving behind a pulsar?

The only parts of a nonrotating black hole that are necessary for its complete description are:

How much mass is lost when two 1-Mε neutron stars merge?

Take two identical, nonrotating, 5-Mε black holes and place them side by side. Add 1 Mε of neutrons to the left-hand one and 1 Mε of protons to the right-hand one (without changing the rotation of the black holes). Afterward, how do these two black holes differ?

The mass of the candidate black hole at the center of the galaxy NGC 4261 was estimated from the:

Astronomy and the Universe

Knowing the Heavens

Eclipses and the Motion of the Moon

Gravitation and the Waltz of the Planets

The Nature of Light

Optics and Telescopes

Comparative Planetology I: Our Solar System

Comparative Planetology II: the Origin of Our Solar System

The Living Earth

Our Barren Moon

Mercury, Venus, and Mars: Terrestrial, yet Unique

Jupiter and Saturn: Lords of the Planets

Jupiter and Saturns Satellites of Fire and Ice

Uranus, Neptune, Pluto, and the Kuiper Belt: Remote Worlds

Asteroids, Comets, and Impacts

Our Star, the Sun

The Nature of the Stars

The Birth of Stars

Stellar Evolution: on and After the Main Sequence

Stellar Evolution: The Death of Stars

Our Galaxy

Galaxies

Quasars and Active Galaxies

Cosmology: The Origin and Evolution of the Universe

Exploring the Early Universe

The Search for Extraterrestrial Life

Filters

How much mass is lost when two 1-M_ε neutron stars merge?

Take two identical, nonrotating, 5-M_ε black holes and place them side by side. Add 1 M_ε of neutrons to the left-hand one and 1 M_ε of protons to the right-hand one (without changing the rotation of the black holes). Afterward, how do these two black holes differ?