Question 1

Which major astronomical event was apparently recorded faithfully by Chinese astronomers in the Sung Dynasty in 1054 C.E.?

Accepted Answer

A) a supernova explosion in our galaxy, visible even in daylight 
B) the passage of the planet Venus across the face of the Sun, a solar transit 
C) the discovery of the planet Mercury 
D) the total eclipse of the Sun in that year 
A) a supernova explosion in our galaxy, visible even in daylight 
B) the passage of the planet Venus across the face of the Sun, a solar transit 
C) the discovery of the planet Mercury 
D) the total eclipse of the Sun in that year

Question 2

Which of the following properties of a massive rotating star will be enhanced if the star collapses into a black hole?

Accepted Answer

A) the intensity of light emitted by it 
B) angular rotation speed 
C) electric charge 
D) mass 
A) the intensity of light emitted by it 
B) angular rotation speed 
C) electric charge 
D) mass

Question 3

If an astronomical source of electromagnetic radiation is observed to flicker, with intensity changes in as short a time as 1/30 s, how large is the emitting region?

Accepted Answer

A) 10,000 km, a little smaller than Earth 
B) 1/30 ly 
C) 9 × 106 km, about 6 times the size of the Sun 
D) 10,000 m, about the size of a small city or town 
A) 10,000 km, a little smaller than Earth 
B) 1/30 ly 
C) 9 × 106 km, about 6 times the size of the Sun 
D) 10,000 m, about the size of a small city or town

Question 4

What is the upper limit to the mass of a neutron star beyond which neutron degeneracy pressure is unable to withstand the force of gravity and the neutron star is crushed out of existence into a black hole?

Accepted Answer

A) 1.4 Mε 
B) 20 Mε 
C) about 100 Mε 
D) about 3 Mε 
A) 1.4 Mε 
B) 20 Mε 
C) about 100 Mε 
D) about 3 Mε

Question 5

What property of gamma-ray bursters indicates that they are located at large ("cosmological") distances from Earth?

Accepted Answer

A) their positions correlating with galaxies known to be at large distances 
B) the small apparent sizes of the objects producing the bursts 
C) highly redshifted emission lines from the burster's nucleus 
D) the faintness of the bursts 
A) their positions correlating with galaxies known to be at large distances 
B) the small apparent sizes of the objects producing the bursts 
C) highly redshifted emission lines from the burster's nucleus 
D) the faintness of the bursts

Question 6

What is the approximate order of magnitude for the change in length in a detector arm caused by a passing gravitational wave?

Accepted Answer

A) 10-10 m 
B) 10-20 m 
C) 10-30 m 
D) 10-40 m 
A) 10-10 m 
B) 10-20 m 
C) 10-30 m 
D) 10-40 m

Question 7

Each of the following is a theoretical difference between a rotating and a nonrotating black hole EXCEPT ONE. Which is the exception?

Accepted Answer

A) The singularity for a nonrotating black hole is a mathematical point, whereas the singularity for a rotating black hole is a ring. 
B) A nonrotating black hole has an event horizon; a rotating black hole has none. 
C) It is possible to extract energy from a rotating black hole but not from a nonrotating black hole. 
D) A rotating black hole has an ergoregion; a nonrotating black hole has none. 
A) The singularity for a nonrotating black hole is a mathematical point, whereas the singularity for a rotating black hole is a ring. 
B) A nonrotating black hole has an event horizon; a rotating black hole has none. 
C) It is possible to extract energy from a rotating black hole but not from a nonrotating black hole. 
D) A rotating black hole has an ergoregion; a nonrotating black hole has none.

Question 8

Which of the following was discovered first?

Accepted Answer

A) Supermassive black hole 
B) Stellar mass black hole 
C) Primordial black hole 
D) Intermediate mass black hole 
A) Supermassive black hole 
B) Stellar mass black hole 
C) Primordial black hole 
D) Intermediate mass black hole

Question 9

We believe the bright central object in the galaxy NGC 4261 is only about the size of our solar system. What evidence do we have for this size estimate?

Accepted Answer

A) This is a direct measurement from the image seen with the HST. 
B) We have measured and compared the Doppler shifts for material on the near and far sides of the object. 
C) Radiation from this central object fluctuates, and the light can only travel this distance (the size of the solar system) during a typical fluctuation. 
D) We estimate the mass of this central object to be 1.2 billion M ? , and this is the Schwarzschild radius that gives nuclear matter density for this mass. 
A) This is a direct measurement from the image seen with the HST. 
B) We have measured and compared the Doppler shifts for material on the near and far sides of the object. 
C) Radiation from this central object fluctuates, and the light can only travel this distance (the size of the solar system) during a typical fluctuation. 
D) We estimate the mass of this central object to be 1.2 billion M ? , and this is the Schwarzschild radius that gives nuclear matter density for this mass.

Question 10

Einstein's principle of equivalence in his general theory of relativity asserts that:

Accepted Answer

A) the behavior of all types of atoms in a gravitational field is equivalent. 
B) all objects are attracted toward all other objects in the universe by gravitational forces. 
C) being at rest in a gravitational field is equivalent to being in an upwardly accelerated frame of reference in a gravity-free environment. 
D) if person B is in a rapidly moving reference frame (moving at constant velocity), then person B will observe exactly the same effects for person A as person A observes for person 
A) the behavior of all types of atoms in a gravitational field is equivalent. 
B) all objects are attracted toward all other objects in the universe by gravitational forces. 
C) being at rest in a gravitational field is equivalent to being in an upwardly accelerated frame of reference in a gravity-free environment. 
D) if person B is in a rapidly moving reference frame (moving at constant velocity), then person B will observe exactly the same effects for person A as person A observes for person

Question 11

The gravitational redshift of light leaving the surface of Sirius B is Δλ /λ = 3.0 × 10-4. What velocity of Sirius B (relative to Earth) would be needed to produce an equivalent Doppler shift?

Accepted Answer

A) 90 km/s away from Earth 
B) 90 km/s toward Earth 
C) 300 km/s away from Earth 
D) 300 km/s toward Earth 
A) 90 km/s away from Earth 
B) 90 km/s toward Earth 
C) 300 km/s away from Earth 
D) 300 km/s toward Earth

Question 12

As light moves outward from the vicinity of a black hole:

Accepted Answer

A) its energy increases. 
B) its energy decreases. 
C) its energy remains the same. 
D) the photons are stopped and remain suspended in space. 
A) its energy increases. 
B) its energy decreases. 
C) its energy remains the same. 
D) the photons are stopped and remain suspended in space.

Question 13

Theoretically, a black hole can have:

Accepted Answer

A) any mass greater than 0.04 Mε. 
B) any mass greater than 3 Mε. 
C) any mass greater than 14.8 Mε. 
D) any mass. 
A) any mass greater than 0.04 Mε. 
B) any mass greater than 3 Mε. 
C) any mass greater than 14.8 Mε. 
D) any mass.

Question 14

Far outside a black hole, space seems flat and times seems independent of space. But, inside the event horizon of a black hole, it would be readily apparent that:

Accepted Answer

A) time flows backward. 
B) time and space are interchanged, each replacing the other. 
C) time and space are interdependent, each depending on the other. 
D) neither time nor space exists. 
A) time flows backward. 
B) time and space are interchanged, each replacing the other. 
C) time and space are interdependent, each depending on the other. 
D) neither time nor space exists.

Question 15

What is the duration of a gamma-ray burst?

Accepted Answer

A) as short as one-hundredth of a second, indicating a source smaller than Earth 
B) several days, indicating a size much smaller than the distance from Earth to the nearest star beyond the Sun 
C) up to about 1 day, indicating a source several times the size of our solar system 
D) several hours, indicating a source size about equal to the diameter of Uranus's orbit 
A) as short as one-hundredth of a second, indicating a source smaller than Earth 
B) several days, indicating a size much smaller than the distance from Earth to the nearest star beyond the Sun 
C) up to about 1 day, indicating a source several times the size of our solar system 
D) several hours, indicating a source size about equal to the diameter of Uranus's orbit

Question 16

The first two gravitational wave detectors were built in the United States. Where did the third detector come online in 2017?

Accepted Answer

A) Germany 
B) South Africa 
C) India 
D) Italy 
A) Germany 
B) South Africa 
C) India 
D) Italy

Question 17

Ancient Chinese astronomers recorded the appearance of what phenomenon in 1054 C.E.?

Accepted Answer

A) a nearby nova explosion in our galaxy 
B) a brilliant auroral display covering the whole Earth 
C) a supernova, visible in daylight 
D) a bright binary star undergoing eclipse 
A) a nearby nova explosion in our galaxy 
B) a brilliant auroral display covering the whole Earth 
C) a supernova, visible in daylight 
D) a bright binary star undergoing eclipse

Question 18

A space freighter accidentally drops a steel beam while passing a black hole, and the beam starts falling toward the black hole with the long axis of the beam pointing toward the black hole. What happens to the beam as it approaches the event horizon?

Accepted Answer

A) It begins to rotate faster and faster. 
B) It is stretched in length. 
C) Nothing happens to its length or rotation; it simply falls faster and faster. 
D) It is compressed in length. 
A) It begins to rotate faster and faster. 
B) It is stretched in length. 
C) Nothing happens to its length or rotation; it simply falls faster and faster. 
D) It is compressed in length.

Question 19

Suppose that, from a stationary spaceship, you identify a source of hydrogen (Hα) light on the surface of a planet that has a very strong gravitational field. When you observe an equivalent Hα light source on your spaceship, the wavelength is 656.3 nm. How long is the wavelength you measure when you look at the light source on the planet?

Accepted Answer

A) shorter than 656.3 nm 
B) the same wavelength of 656.3 nm, but the frequency of the light appears lower 
C) 656.3 nm, the same as your light source, but the source appears very faint because the radiation has been weakened by the gravity field 
D) longer than 656.3 nm 
A) shorter than 656.3 nm 
B) the same wavelength of 656.3 nm, but the frequency of the light appears lower 
C) 656.3 nm, the same as your light source, but the source appears very faint because the radiation has been weakened by the gravity field 
D) longer than 656.3 nm

Question 20

What happens to the radius of the event horizon of a black hole if you triple its mass?

Accepted Answer

A) It decreases to 1/3 the size. 
B) It becomes 3 times bigger. 
C) It decreases to 1/9 the size. 
D) It becomes 9 times bigger. 
A) It decreases to 1/3 the size. 
B) It becomes 3 times bigger. 
C) It decreases to 1/9 the size. 
D) It becomes 9 times bigger.

Exam 21: Stellar Remnants: Neutron Stars and Black Holes

Which major astronomical event was apparently recorded faithfully by Chinese astronomers in the Sung Dynasty in 1054 C.E.?

Which of the following properties of a massive rotating star will be enhanced if the star collapses into a black hole?

If an astronomical source of electromagnetic radiation is observed to flicker, with intensity changes in as short a time as 1/30 s, how large is the emitting region?

What is the upper limit to the mass of a neutron star beyond which neutron degeneracy pressure is unable to withstand the force of gravity and the neutron star is crushed out of existence into a black hole?

What property of gamma-ray bursters indicates that they are located at large ("cosmological") distances from Earth?

What is the approximate order of magnitude for the change in length in a detector arm caused by a passing gravitational wave?

Each of the following is a theoretical difference between a rotating and a nonrotating black hole EXCEPT ONE. Which is the exception?

Which of the following was discovered first?

We believe the bright central object in the galaxy NGC 4261 is only about the size of our solar system. What evidence do we have for this size estimate?

Einstein's principle of equivalence in his general theory of relativity asserts that:

The gravitational redshift of light leaving the surface of Sirius B is Δλ /λ = 3.0 × 10-4. What velocity of Sirius B (relative to Earth) would be needed to produce an equivalent Doppler shift?

As light moves outward from the vicinity of a black hole:

Theoretically, a black hole can have:

Far outside a black hole, space seems flat and times seems independent of space. But, inside the event horizon of a black hole, it would be readily apparent that:

What is the duration of a gamma-ray burst?

The first two gravitational wave detectors were built in the United States. Where did the third detector come online in 2017?

Ancient Chinese astronomers recorded the appearance of what phenomenon in 1054 C.E.?

A space freighter accidentally drops a steel beam while passing a black hole, and the beam starts falling toward the black hole with the long axis of the beam pointing toward the black hole. What happens to the beam as it approaches the event horizon?

What happens to the radius of the event horizon of a black hole if you triple its mass?

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Gravitation and the Waltz of the Planets

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Comparative Planetology II: the Origin of Our Solar System

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Mercury, Venus, and Mars: Terrestrial, yet Unique

Jupiter and Saturn: Lords of the Planets

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

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Stellar Evolution: on and After the Main Sequence

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The gravitational redshift of light leaving the surface of Sirius B is Δλ /λ = 3.0 × 10^-4. What velocity of Sirius B (relative to Earth) would be needed to produce an equivalent Doppler shift?