Question 1

All evolutionary differences between high- and low-mass stars can be attributed to differences in the amount of gravity each star possesses.

Accepted Answer

A) True 
 B)False

Question 2

Examine the figure below.Hydrogen burns through the CNO cycle only in high-mass main-sequence stars because of the greater __________ in their cores.

Accepted Answer

A)  concentration of heavy elements like carbon 
B)  densities 
C)  abundance of hydrogen 
D)  temperatures 
A)  concentration of heavy elements like carbon 
B)  densities 
C)  abundance of hydrogen 
D)  temperatures

Question 3

Black holes have an infinitely small radius,but a finite event horizon.

Accepted Answer

A) True 
 B)False

Question 4

While traveling the galaxy in a spacecraft,you and a colleague set out to investigate the 106 M$\bigodot$ black hole at the center of our galaxy.Your colleague hops aboard an escape pod and drops into a circular orbit around the black hole,maintaining a distance of 1 AU,while you remain much farther away in the spacecraft but from which you can easily monitor your colleague.After doing some experiments to measure the strength of gravity,your colleague signals his/her results back to you using a green laser.What would you see?

Accepted Answer

A)  His/her signals,because he/she is orbiting well outside the event horizon. 
B)  His/her signals,but shifted to a much redder wavelength because he/she is very close to the event horizon. 
C)  Nothing,because your colleague has crossed the event horizon. 
D)  Nothing,because no light can escape the gravitational pull of a black hole no matter how close he/she is to it. 
A)  His/her signals,because he/she is orbiting well outside the event horizon. 
B)  His/her signals,but shifted to a much redder wavelength because he/she is very close to the event horizon. 
C)  Nothing,because your colleague has crossed the event horizon. 
D)  Nothing,because no light can escape the gravitational pull of a black hole no matter how close he/she is to it.

Question 5

What would happen if mass were continually added to a 2 M$\bigodot$neutron star?

Accepted Answer

A)  The star's radius would increase. 
B)  The star would eventually become a black hole. 
C)  The star would erupt as a nova. 
D)  All of the above would occur. 
A)  The star's radius would increase. 
B)  The star would eventually become a black hole. 
C)  The star would erupt as a nova. 
D)  All of the above would occur.

Question 6

Essentially all the elements heavier than iron in our galaxy were formed:

Accepted Answer

A)  by supernovae 
B)  during the formation of black holes 
C)  by fusion in the cores of the most massive main-sequence stars 
D)  during the formation of planetary nebulae 
A)  by supernovae 
B)  during the formation of black holes 
C)  by fusion in the cores of the most massive main-sequence stars 
D)  during the formation of planetary nebulae

Question 7

The equivalence principle says that:

Accepted Answer

A)  being stationary in a gravitational field is the same as being in an accelerated reference frame 
B)  the universe is homogeneous and isotropic 
C)  at any radius inside a star the outward gas pressure must balance the weight of the material on top 
D)  mass and energy are interchangeable and neither can be destroyed 
A)  being stationary in a gravitational field is the same as being in an accelerated reference frame 
B)  the universe is homogeneous and isotropic 
C)  at any radius inside a star the outward gas pressure must balance the weight of the material on top 
D)  mass and energy are interchangeable and neither can be destroyed

Question 8

Most of the uranium (U; atomic mass = 238)found on the Earth was formed in Type II supernovae explosions.

Accepted Answer

A) True 
 B)False

Question 9

Gravitational lensing occurs when __________ distorts the fabric of spacetime.

Accepted Answer

A)  a star 
B)  dark matter 
C)  a black hole 
D)  any massive object 
A)  a star 
B)  dark matter 
C)  a black hole 
D)  any massive object

Question 10

The event horizon of a black hole is defined as:

Accepted Answer

A)  the point of maximum gravity 
B)  the radius of the original neutron star before it became a black hole 
C)  the point at which shock waves emanate from the strong gravitational distortion the black hole creates in the fabric of spacetime 
D)  the radius at which the escape speed equals the speed of light 
A)  the point of maximum gravity 
B)  the radius of the original neutron star before it became a black hole 
C)  the point at which shock waves emanate from the strong gravitational distortion the black hole creates in the fabric of spacetime 
D)  the radius at which the escape speed equals the speed of light

Question 11

Which of the following is a consequence of Einstein's special theory of relativity?

Accepted Answer

A)  Moving clocks run quicker. 
B)  The velocity of light depends on the speed of the observer. 
C)  Distances appear shorter when traveling near the speed of light. 
D)  Gravity arises because mass distorts spacetime. 
A)  Moving clocks run quicker. 
B)  The velocity of light depends on the speed of the observer. 
C)  Distances appear shorter when traveling near the speed of light. 
D)  Gravity arises because mass distorts spacetime.

Question 12

What is the difference between the singularity and the event horizon of a black hole?

Accepted Answer

The singularity is the very center of th

Question 13

As a high-mass main-sequence star evolves off the main sequence,it follows a __________ on the H-R diagram.

Accepted Answer

A)  nearly vertical path 
B)  path of constant radius 
C)  roughly horizontal path 
D)  None of the above answers is correct. 
A)  nearly vertical path 
B)  path of constant radius 
C)  roughly horizontal path 
D)  None of the above answers is correct.

Question 14

While traveling the galaxy in a spacecraft,you and a colleague set out to investigate a 1 M$\bigodot$ black hole.Your colleague hops aboard an escape pod and drops into a circular orbit around the black hole maintaining a distance of 10 km from it,while you remain much farther away inside the spacecraft.After doing some experiments to measure the strength of gravity,your colleague signals the results back to you using a green laser.What would you see,and why?

Accepted Answer

The event horizon is at a radius of 3km

Question 15

Photons have no mass,and Einstein's theory of general relativity says:

Accepted Answer

A)  their paths through spacetime are curved in the presence of a massive body 
B)  their apparent speeds depend on the observer's frame of reference 
C)  they should not be attracted to a massive object 
D)  their wavelengths must remain the same as they travel through spacetime 
A)  their paths through spacetime are curved in the presence of a massive body 
B)  their apparent speeds depend on the observer's frame of reference 
C)  they should not be attracted to a massive object 
D)  their wavelengths must remain the same as they travel through spacetime

Question 16

Explain why Einstein's theory of general relativity predicts the existence of gravitational lensing.

Accepted Answer

Einstein's theory of general relativity

Question 17

Type Ia and Type II supernovae are approximately equal in luminosity.

Accepted Answer

A) True 
 B)False

Question 18

Black holes that are stellar remnants can be found by searching for:

Accepted Answer

A)  dark regions at the centers of galaxies 
B)  variable X-ray sources 
C)  extremely luminous infrared objects 
D)  objects that emit very faint radio emission 
A)  dark regions at the centers of galaxies 
B)  variable X-ray sources 
C)  extremely luminous infrared objects 
D)  objects that emit very faint radio emission

Question 19

Why does the luminosity of a high-mass star remain nearly constant as the star burns heavy elements in its core,even though it is producing millions of times more energy per second than it did on the main sequence?

Accepted Answer

A)  Most of the energy is trapped in the core,increasing the core's temperature. 
B)  All of the extra energy goes into heating the shells of fusion surrounding the core. 
C)  Most of the energy is absorbed by the outer layers of the star,increasing the star's radius but leaving its luminosity unchanged. 
D)  Most of the energy is carried out of the star by escaping neutrinos. 
A)  Most of the energy is trapped in the core,increasing the core's temperature. 
B)  All of the extra energy goes into heating the shells of fusion surrounding the core. 
C)  Most of the energy is absorbed by the outer layers of the star,increasing the star's radius but leaving its luminosity unchanged. 
D)  Most of the energy is carried out of the star by escaping neutrinos.

Question 20

Assume that a group of explorers traveled to the Orion Nebula,the nearest star-forming cloud at a distance of 1,300 light-years,using revolutionary technology that allowed them to travel at a speed very close to the speed of light.Observers back on Earth would say it took them __________ to get there,but the travelers would say it took them __________ to get there.

Accepted Answer

A)  slightly more than 1,300 years; much less than 1,300 years 
B)  slightly more than 1,300 years; slightly less than 1,300 years 
C)  slightly less than 1,300 years; slightly more than 1,300 years 
D)  exactly 1,300 years; much less than 1,300 years 
A)  slightly more than 1,300 years; much less than 1,300 years 
B)  slightly more than 1,300 years; slightly less than 1,300 years 
C)  slightly less than 1,300 years; slightly more than 1,300 years 
D)  exactly 1,300 years; much less than 1,300 years

All evolutionary differences between high- and low-mass stars can be attributed to differences in the amount of gravity each star possesses.

Examine the figure below.Hydrogen burns through the CNO cycle only in high-mass main-sequence stars because of the greater __________ in their cores.

Black holes have an infinitely small radius,but a finite event horizon.

What would happen if mass were continually added to a 2 M_$\bigodot$neutron star?

Essentially all the elements heavier than iron in our galaxy were formed:

The equivalence principle says that:

Most of the uranium (U; atomic mass = 238)found on the Earth was formed in Type II supernovae explosions.

Gravitational lensing occurs when __________ distorts the fabric of spacetime.

The event horizon of a black hole is defined as:

Which of the following is a consequence of Einstein's special theory of relativity?

What is the difference between the singularity and the event horizon of a black hole?

As a high-mass main-sequence star evolves off the main sequence,it follows a __________ on the H-R diagram.

Photons have no mass,and Einstein's theory of general relativity says:

Explain why Einstein's theory of general relativity predicts the existence of gravitational lensing.

Type Ia and Type II supernovae are approximately equal in luminosity.

Black holes that are stellar remnants can be found by searching for:

Why does the luminosity of a high-mass star remain nearly constant as the star burns heavy elements in its core,even though it is producing millions of times more energy per second than it did on the main sequence?

Our Place in the Universe

Patterns in the Skymotions of Earth

Laws of Motion

Light and Telescopes

The Formation of Stars and Planets

Terrestrial Worlds in the Inner Solar System

Atmospheres of Venus, Earth, and Mars

The Giant Planets

Small Bodies of the Solar System

Measuring the Stars

Our Star: The Sun

Evolution of Low-Mass Stars

The Expansion of Space

The Realm of the Galaxies

Our Galaxy: The Milky Way

Modern Cosmology and the Origin of Structure

Life in the Universe

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Exam 13: Evolution of High-Mass Stars

All evolutionary differences between high- and low-mass stars can be attributed to differences in the amount of gravity each star possesses.

Examine the figure below.Hydrogen burns through the CNO cycle only in high-mass main-sequence stars because of the greater __________ in their cores.

Black holes have an infinitely small radius,but a finite event horizon.

What would happen if mass were continually added to a 2 M ⨀\bigodot⨀ neutron star?

Essentially all the elements heavier than iron in our galaxy were formed:

The equivalence principle says that:

Most of the uranium (U; atomic mass = 238)found on the Earth was formed in Type II supernovae explosions.

Gravitational lensing occurs when __________ distorts the fabric of spacetime.

The event horizon of a black hole is defined as:

Which of the following is a consequence of Einstein's special theory of relativity?

What is the difference between the singularity and the event horizon of a black hole?

As a high-mass main-sequence star evolves off the main sequence,it follows a __________ on the H-R diagram.

Photons have no mass,and Einstein's theory of general relativity says:

Explain why Einstein's theory of general relativity predicts the existence of gravitational lensing.

Type Ia and Type II supernovae are approximately equal in luminosity.

Black holes that are stellar remnants can be found by searching for:

Why does the luminosity of a high-mass star remain nearly constant as the star burns heavy elements in its core,even though it is producing millions of times more energy per second than it did on the main sequence?

Our Place in the Universe

Patterns in the Skymotions of Earth

Laws of Motion

Light and Telescopes

The Formation of Stars and Planets

Terrestrial Worlds in the Inner Solar System

Atmospheres of Venus, Earth, and Mars

The Giant Planets

Small Bodies of the Solar System

Measuring the Stars

Our Star: The Sun

Evolution of Low-Mass Stars

The Expansion of Space

The Realm of the Galaxies

Our Galaxy: The Milky Way

Modern Cosmology and the Origin of Structure

Life in the Universe

Filters

What would happen if mass were continually added to a 2 M_$\bigodot$neutron star?