Question 1

For a massive star,core hydrogen burning lasts for several million years.In contrast,core silicon burning lasts for only about

Accepted Answer

A)  1 day. 
B)  1 minute. 
C)  600 years. 
D)  1 year. 
A)  1 day. 
B)  1 minute. 
C)  600 years. 
D)  1 year.

Question 2

What is the relationship between neutron stars and the Chandrasekhar limit?

Accepted Answer

A)  The Chandrasekhar limit is an upper-mass limit for the stability of any massive system;it applies to any system,no matter how it was formed,including neutron stars. 
B)  The Chandrasekhar limit applies only to systems stabilized by degenerate electrons;neutron stars are stabilized by the pressure of the neutron degeneracy. 
C)  The Chandrasekhar limit applies specifically to the neutron degeneracy and thus to neutron stars. 
D)  The Chandrasekhar limit applies to radius,not mass.Thus,as long as a neutron star is big enough,it will not be affected by the Chandrasekhar limit. 
A)  The Chandrasekhar limit is an upper-mass limit for the stability of any massive system;it applies to any system,no matter how it was formed,including neutron stars. 
B)  The Chandrasekhar limit applies only to systems stabilized by degenerate electrons;neutron stars are stabilized by the pressure of the neutron degeneracy. 
C)  The Chandrasekhar limit applies specifically to the neutron degeneracy and thus to neutron stars. 
D)  The Chandrasekhar limit applies to radius,not mass.Thus,as long as a neutron star is big enough,it will not be affected by the Chandrasekhar limit.

Question 3

If a black hole is truly black and has an escape velocity greater than the speed of light such that no light can escape it,where do the X-rays come from in the black hole candidates so far identified?

Accepted Answer

A)  From stars behind the black hole,whose light is focused and concentrated by gravitational focusing to the point where it becomes X-ray radiation 
B)  The black hole is only black to visible radiation traveling at the speed of light,but because X-rays travel faster than the speed of light,they can escape. 
C)  From the normal star accompanying the black hole,its ordinary light being blueshifted into the X-ray spectral region by the intense gravity of the black hole 
D)  From the matter surrounding the black hole,which is highly condensed and hence very hot 
A)  From stars behind the black hole,whose light is focused and concentrated by gravitational focusing to the point where it becomes X-ray radiation 
B)  The black hole is only black to visible radiation traveling at the speed of light,but because X-rays travel faster than the speed of light,they can escape. 
C)  From the normal star accompanying the black hole,its ordinary light being blueshifted into the X-ray spectral region by the intense gravity of the black hole 
D)  From the matter surrounding the black hole,which is highly condensed and hence very hot

Question 4

When a supernova explosion results from core collapse in a massive star it appears to leave behind

Accepted Answer

A)  a rapidly expanding shell of gas and a central neutron star or black hole. 
B)  a rapidly rotating shell of gas,dust,and radiation,but no central object. 
C)  a rapidly expanding shell of gas and a compact white-dwarf star at its center. 
D)  nothing,the explosion changes all the matter completely into energy,which then radiates into space at the speed of light. 
A)  a rapidly expanding shell of gas and a central neutron star or black hole. 
B)  a rapidly rotating shell of gas,dust,and radiation,but no central object. 
C)  a rapidly expanding shell of gas and a compact white-dwarf star at its center. 
D)  nothing,the explosion changes all the matter completely into energy,which then radiates into space at the speed of light.

Question 5

Because light cannot escape from a black hole,there is no evidence that they actually exist.

Accepted Answer

A) True 
 B)False

Question 6

What is the likely final fate of a star that has a mass of greater than 15 solar masses after completing its nuclear fusion-burning phases?

Accepted Answer

A)  It undergoes fission and immediately splits in two to become a binary star system. 
B)  The degeneracy of the electrons within the star prevents collapse beyond the diameter of a white dwarf. 
C)  It condenses to the point where it is composed completely of neutrons,the degeneracy of which prevents further shrinkage. 
D)  It collapses and becomes a black hole. 
A)  It undergoes fission and immediately splits in two to become a binary star system. 
B)  The degeneracy of the electrons within the star prevents collapse beyond the diameter of a white dwarf. 
C)  It condenses to the point where it is composed completely of neutrons,the degeneracy of which prevents further shrinkage. 
D)  It collapses and becomes a black hole.

Question 7

What is the difference between a nova and an X-ray burster,and how are they similar?

Accepted Answer

Both are compact objects orbiting a comp

Question 8

A supernova's incomprehensively large energy release stems mainly from

Accepted Answer

A)  thermonuclear reactions. 
B)  the gravitational energy released by the core and outer layers. 
C)  the electromagnetic interactions. 
D)  the weak nuclear force. 
A)  thermonuclear reactions. 
B)  the gravitational energy released by the core and outer layers. 
C)  the electromagnetic interactions. 
D)  the weak nuclear force.

Question 9

The evolutionary stage of a very large star that lasts the longest is when it is going through hydrogen fusion.

Accepted Answer

A) True 
 B)False

Question 10

Type II supernovae show prominent lines of hydrogen in their spectra,whereas hydrogen lines are absent in spectra of Type Ia supernovae.Why is this? (Hint: Think about the type of star that gives rise to each of the two types of supernova. )

Accepted Answer

A)  Massive stars have burned all of their hydrogen into heavier elements,whereas low-mass stars still have large hydrogen-rich envelopes. 
B)  Massive stars contain large amounts of hydrogen,whereas white dwarfs are mostly carbon and oxygen. 
C)  White dwarfs have a thick surface layer of hydrogen,whereas neutron stars contain no hydrogen at all. 
D)  Massive stars contain large amounts of hydrogen,whereas neutron stars contain no hydrogen at all. 
A)  Massive stars have burned all of their hydrogen into heavier elements,whereas low-mass stars still have large hydrogen-rich envelopes. 
B)  Massive stars contain large amounts of hydrogen,whereas white dwarfs are mostly carbon and oxygen. 
C)  White dwarfs have a thick surface layer of hydrogen,whereas neutron stars contain no hydrogen at all. 
D)  Massive stars contain large amounts of hydrogen,whereas neutron stars contain no hydrogen at all.

Question 11

What is the source of energy that allowed supernova 1987A to continue to brighten slowly for a few months after its initial explosion?

Accepted Answer

A)  Radioactive decay of specific nuclei produced in the explosion 
B)  Thermonuclear reactions between iron nuclei and protons,neutrons,and helium nuclei 
C)  Thermonuclear reactions between hydrogen nuclei in the shell of gas surrounding the supernova,triggered by the shock wave from the explosion 
D)  Slow gravitational compression of the remnant core of the supernova and the consequent release of gravitational potential energy 
A)  Radioactive decay of specific nuclei produced in the explosion 
B)  Thermonuclear reactions between iron nuclei and protons,neutrons,and helium nuclei 
C)  Thermonuclear reactions between hydrogen nuclei in the shell of gas surrounding the supernova,triggered by the shock wave from the explosion 
D)  Slow gravitational compression of the remnant core of the supernova and the consequent release of gravitational potential energy

Question 12

Pairs of jets carrying material and radiation outward in opposite directions have been detected (or inferred)for all of the following types of objects EXCEPT

Accepted Answer

A)  stellar-mass black hole candidates. 
B)  supermassive black hole candidates. 
C)  protostars. 
D)  white dwarfs. 
A)  stellar-mass black hole candidates. 
B)  supermassive black hole candidates. 
C)  protostars. 
D)  white dwarfs.

Question 13

The Schwarzschild radius describes the maximum radius that a white dwarf can have.

Accepted Answer

A) True 
 B)False

Question 14

The pulsation periods of most pulsars range from

Accepted Answer

A)  1/1000 second to a few seconds. 
B)  10-6 to 10-3 second. 
C)  minutes to hours. 
D)  many hours to a few days. 
A)  1/1000 second to a few seconds. 
B)  10-6 to 10-3 second. 
C)  minutes to hours. 
D)  many hours to a few days.

Question 15

A sequence of thermonuclear fusion processes inside massive stars can continue to transform the nuclei of elements such as carbon,oxygen,and so forth,into heavier nuclei AND also generate excess energy,up to a limit beyond which no further energy-producing reactions can occur.The element that is produced when this limit is reached is

Accepted Answer

A)  lead. 
B)  oxygen. 
C)  uranium. 
D)  iron. 
A)  lead. 
B)  oxygen. 
C)  uranium. 
D)  iron.

Question 16

What is the main observational difference between a Type I and a Type II supernova?

Accepted Answer

A)  Hydrogen lines are prominent in the spectrum of a Type II supernova but absent in that of Type I. 
B)  The spectrum of a Type II supernova shows strong lines of both hydrogen and helium,whereas that of Type I shows only hydrogen. 
C)  The spectrum of a Type I supernova shows strong lines of both hydrogen and helium,whereas that of Type II shows only hydrogen. 
D)  Hydrogen lines are prominent in the spectrum of a Type I supernova but absent in that of Type II. 
A)  Hydrogen lines are prominent in the spectrum of a Type II supernova but absent in that of Type I. 
B)  The spectrum of a Type II supernova shows strong lines of both hydrogen and helium,whereas that of Type I shows only hydrogen. 
C)  The spectrum of a Type I supernova shows strong lines of both hydrogen and helium,whereas that of Type II shows only hydrogen. 
D)  Hydrogen lines are prominent in the spectrum of a Type I supernova but absent in that of Type II.

Question 17

A white dwarf is a stellar corpse supported by

Accepted Answer

A)  electron degeneracy pressure. 
B)  neutron degeneracy pressure. 
C)  black hole pressure. 
D)  None of these 
A)  electron degeneracy pressure. 
B)  neutron degeneracy pressure. 
C)  black hole pressure. 
D)  None of these

Question 18

The first pulsar was detected using

Accepted Answer

A)  the infrared satellite IRAS. 
B)  a British radio telescope. 
C)  the unaided eye,by Chinese astronomers. 
D)  the 200-inch telescope at Mount Palomar. 
A)  the infrared satellite IRAS. 
B)  a British radio telescope. 
C)  the unaided eye,by Chinese astronomers. 
D)  the 200-inch telescope at Mount Palomar.

Question 19

What would happen to Earth's orbit if the Sun were to suddenly turn into a black hole?

Accepted Answer

A)  It would continue in its current orbit. 
B)  It would spiral away. 
C)  It would be sucked in. 
D)  It is impossible to determine. 
A)  It would continue in its current orbit. 
B)  It would spiral away. 
C)  It would be sucked in. 
D)  It is impossible to determine.

Question 20

Pulsars are

Accepted Answer

A)  pulsating white dwarfs. 
B)  pulsating neutron stars. 
C)  pulsating black holes. 
D)  rotating neutron stars. 
A)  pulsating white dwarfs. 
B)  pulsating neutron stars. 
C)  pulsating black holes. 
D)  rotating neutron stars.

For a massive star,core hydrogen burning lasts for several million years.In contrast,core silicon burning lasts for only about

What is the relationship between neutron stars and the Chandrasekhar limit?

If a black hole is truly black and has an escape velocity greater than the speed of light such that no light can escape it,where do the X-rays come from in the black hole candidates so far identified?

When a supernova explosion results from core collapse in a massive star it appears to leave behind

Because light cannot escape from a black hole,there is no evidence that they actually exist.

What is the likely final fate of a star that has a mass of greater than 15 solar masses after completing its nuclear fusion-burning phases?

What is the difference between a nova and an X-ray burster,and how are they similar?

A supernova's incomprehensively large energy release stems mainly from

The evolutionary stage of a very large star that lasts the longest is when it is going through hydrogen fusion.

Type II supernovae show prominent lines of hydrogen in their spectra,whereas hydrogen lines are absent in spectra of Type Ia supernovae.Why is this? (Hint: Think about the type of star that gives rise to each of the two types of supernova. )

What is the source of energy that allowed supernova 1987A to continue to brighten slowly for a few months after its initial explosion?

Pairs of jets carrying material and radiation outward in opposite directions have been detected (or inferred)for all of the following types of objects EXCEPT

The Schwarzschild radius describes the maximum radius that a white dwarf can have.

The pulsation periods of most pulsars range from

What is the main observational difference between a Type I and a Type II supernova?

A white dwarf is a stellar corpse supported by

The first pulsar was detected using

What would happen to Earth's orbit if the Sun were to suddenly turn into a black hole?

Pulsars are

Predicting the Motions of the Stars, Sun, and Moon

Decoding the Hidden Messages in Starlight

Analyzing Scales and Motions of the Universe

Exploring Our Evolving Solar System

Uncovering Earths Systems

Exploring Terrestrial Surface Processes and Atmospheres

Observing the Dynamic Giant Planets

Looking for Life Beyond Earth

Probing the Dynamic Sun

Observing Properties of Distant Stars

Inferring Patterns in Star Life Cycles

Exploring Our Galaxy

Investigating Other Galaxies

Observing the Evolution of the Universe

Filters

Exam 12: Predicting the Violent End of the Largest Stars

For a massive star,core hydrogen burning lasts for several million years.In contrast,core silicon burning lasts for only about

What is the relationship between neutron stars and the Chandrasekhar limit?

If a black hole is truly black and has an escape velocity greater than the speed of light such that no light can escape it,where do the X-rays come from in the black hole candidates so far identified?

When a supernova explosion results from core collapse in a massive star it appears to leave behind

Because light cannot escape from a black hole,there is no evidence that they actually exist.

What is the likely final fate of a star that has a mass of greater than 15 solar masses after completing its nuclear fusion-burning phases?

What is the difference between a nova and an X-ray burster,and how are they similar?

A supernova's incomprehensively large energy release stems mainly from

The evolutionary stage of a very large star that lasts the longest is when it is going through hydrogen fusion.

Type II supernovae show prominent lines of hydrogen in their spectra,whereas hydrogen lines are absent in spectra of Type Ia supernovae.Why is this? (Hint: Think about the type of star that gives rise to each of the two types of supernova. )

What is the source of energy that allowed supernova 1987A to continue to brighten slowly for a few months after its initial explosion?

Pairs of jets carrying material and radiation outward in opposite directions have been detected (or inferred)for all of the following types of objects EXCEPT

The Schwarzschild radius describes the maximum radius that a white dwarf can have.

The pulsation periods of most pulsars range from

What is the main observational difference between a Type I and a Type II supernova?

A white dwarf is a stellar corpse supported by

The first pulsar was detected using

What would happen to Earth's orbit if the Sun were to suddenly turn into a black hole?

Pulsars are

Predicting the Motions of the Stars, Sun, and Moon

Decoding the Hidden Messages in Starlight

Analyzing Scales and Motions of the Universe

Exploring Our Evolving Solar System

Uncovering Earths Systems

Exploring Terrestrial Surface Processes and Atmospheres

Observing the Dynamic Giant Planets

Looking for Life Beyond Earth

Probing the Dynamic Sun

Observing Properties of Distant Stars

Inferring Patterns in Star Life Cycles

Exploring Our Galaxy

Investigating Other Galaxies

Observing the Evolution of the Universe

Filters