Question 1

Helium nuclear reactions take place in a shell around the core of a low-mass star during its

Accepted Answer

A)   horizontal-branch phase.
B)   first red-giant phase.
C)   main-sequence phase.
D)   asymptotic giant branch phase.

Question 2

For a massive star (e.g., 25 solar masses) , core hydrogen fusion lasts for several million years. In contrast, the final stage of fusion, core silicon fusion lasts for only about

Accepted Answer

A)   1 minute.
B)   several thousand years.
C)   1 day.
D)   1 year.

Question 3

What is remarkable about the supernova remnant Cassiopeia A?

Accepted Answer

A)   Cassiopeia A contains a binary neutron star system in which one neutron star is significantly more massive than the other.
B)   Cassiopeia A is bright at all wavelengths from radio and visible light to X-rays.
C)   Cassiopeia A is the nearest supernova remnant, located only about 300 ly from Earth.
D)   Cassiopeia A shows that a supernova occurred in the Galaxy about 300 years ago, but there is no record of any supernova having been seen at that time.

Question 4

A nova is an explosion involving a white dwarf. Can a white dwarf become a nova more than once? Why or why not?

Accepted Answer

A)   No. The white dwarf's magnetic field is eliminated in the explosion.
B)   Yes. A white dwarf can become a nova more than once if its temperature is high enough for recurrent helium flashes in the core.
C)   Yes. A white dwarf can become a nova more than once if it continues to receive matter from a companion star.
D)   No. The white dwarf is destroyed in the explosion.

Question 5

The great breakthrough in understanding the nature of pulsars was

Accepted Answer

A)   the discovery of a pulsar in the middle of the Crab Nebula.
B)   the realization that pulsars were found only in the galactic plane.
C)   the connection between pulsars and variable stars.
D)   the discovery that all pulsars have periods that are multiples of a universal pulsar period.

Question 6

A binary system contains a neutron star and a giant star that is slowly transferring mass to the neutron star. What is a likely result of this process?

Accepted Answer

A)   millisecond pulsar
B)   magnetar
C)   soft gamma-ray repeater
D)   white dwarf

Question 7

What is the source of MOST of the heavy elements on Earth and in human bodies?

Accepted Answer

A)   thermonuclear fusion reactions in the cores of massive stars before the supernova phase
B)   explosive nucleosynthesis during supernova explosions of massive stars
C)   cosmic ray interactions with hydrogen and helium nuclei in interstellar clouds
D)   nuclear reactions during the formation of the universe (the Big Bang)

Question 8

During which phase of a low-mass star's life does helium shell fusion occur?

Accepted Answer

A)   main sequence
B)   asymptotic giant branch
C)   first red-giant phase
D)   horizontal branch

Question 9

The existence of stars composed almost entirely of neutrons was first predicted by

Accepted Answer

A)   Jocelyn Bell in 1967.
B)   Stephen Hawking in 1985.
C)   Fritz Zwicky and Walter Baade in 1933.
D)   Albert Einstein in 1908.

Question 10

The period of pulsation for the fastest pulsars is about

Accepted Answer

A)   1/1000 second.
B)   10-6 second.
C)   1 second.
D)   a few minutes.

Question 11

The center of the remnant of a Type Ia supernova MOST likely contains

Accepted Answer

A)   a black hole or neutron star.
B)   a white dwarf.
C)   the binary companion of the supernova's progenitor.
D)   a planetary nebula.

Question 12

A planetary nebula is created

Accepted Answer

A)   over several hundred years, during mass transfer in a close binary star system.
B)   over a few thousand years or more, in a slow expansion away from a low-mass star, driven by a series of thermal pulses from helium fusion.
C)   in hours or less, during the explosion of a massive star.
D)   in seconds, during the helium flash in a low-mass star.

Question 13

How much brighter than its main-sequence luminosity will a Sunlike star become at the asymptotic giant branch (AGB)  phase of its life?

Accepted Answer

A)   10 times brighter
B)   104 times brighter
C)   twice as bright
D)   103 times brighter

Question 14

In the asymptotic giant branch (AGB)  phase of their lives, stars like the Sun lose mass to space through an outflowing "stellar wind." Over a period of 1000 years, how much mass would such a star eject?

Accepted Answer

A)   almost 1/10 solar mass
B)   about 10-5 solar mass
C)   about 1/100 solar mass
D)   almost none since most of the mass flows back in at the star's poles

Question 15

A white dwarf star is at what stage of its evolution?

Accepted Answer

A)   protostar phase, just after formation, beginning to generate energy by nuclear fusion
B)   main-sequence phase, "middle-aged," generating energy by fusion of hydrogen to helium
C)   post-supernova stage, after the explosion of a star
D)   very late phase of evolution, no longer generating energy

Question 16

Around 2 million years ago, astronomers believe, Earth's ozone layer may have been significantly damaged, leading to radiation damage to life on Earth. What is believed to be the cause of the damage?

Accepted Answer

A)   An OB association may have been close enough that a supernova flooded Earth with intense radiation.
B)   The Sun went through its T Tauri expansion.
C)   The Sun sent out a ring of material as it formed a planetary nebula.
D)   The Gum supernova erupted.

Question 17

Each successive stage of core nuclear reactions in a massive star lasts for considerably less time than the previous stage (e.g., for a 25-solar-mass star, carbon fusion lasts for 600 years, while neon fusion lasts for only 1 year) . One reason is that the

Accepted Answer

A)   later the stage of fusion, the less massive is the star.
B)   later the stage of fusion, the more massive is the star.
C)   more massive the nuclei, the fewer there are to react together.
D)   more massive the nuclei, the less stable the end products.

Question 18

Which of these sentences about SN 1987A is NOT true?

Accepted Answer

A)   Bursts of neutrinos were detected at multiple sites from the supernova.
B)   The supernova did not become as intrinsically bright as originally expected.
C)   The supernova was a white dwarf exploding after mass transfer from a companion star in a binary star system.
D)   Observations of the star had been made before it blew up.

Question 19

Helium nuclear reactions (helium fusion)  produce primarily

Accepted Answer

A)   carbon and oxygen.
B)   carbon and silicon.
C)   iron.
D)   oxygen and neon.

Question 20

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

Accepted Answer

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

Exam 14: The Death of Stars

A planetary nebula is created

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During which phase of a low-mass star's life does helium shell fusion occur?

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The center of the remnant of a Type Ia supernova MOST likely contains

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In the asymptotic giant branch (AGB) phase of their lives, stars like the Sun lose mass to space through an outflowing "stellar wind." Over a period of 1000 years, how much mass would such a star eject?

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A binary system contains a neutron star and a giant star that is slowly transferring mass to the neutron star. What is a likely result of this process?

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The period of pulsation for the fastest pulsars is about

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The existence of stars composed almost entirely of neutrons was first predicted by

Correct AnswerverifiedShow Answer

A nova is an explosion involving a white dwarf. Can a white dwarf become a nova more than once? Why or why not?

Correct AnswerverifiedShow Answer

Helium nuclear reactions take place in a shell around the core of a low-mass star during its

Correct AnswerverifiedShow Answer

Each successive stage of core nuclear reactions in a massive star lasts for considerably less time than the previous stage (e.g., for a 25-solar-mass star, carbon fusion lasts for 600 years, while neon fusion lasts for only 1 year) . One reason is that the

Correct AnswerverifiedShow Answer

Around 2 million years ago, astronomers believe, Earth's ozone layer may have been significantly damaged, leading to radiation damage to life on Earth. What is believed to be the cause of the damage?

Correct AnswerverifiedShow Answer

What is remarkable about the supernova remnant Cassiopeia A?

Correct AnswerverifiedShow Answer

Which of these sentences about SN 1987A is NOT true?

Correct AnswerverifiedShow Answer

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

Correct AnswerverifiedShow Answer

The great breakthrough in understanding the nature of pulsars was

Correct AnswerverifiedShow Answer

Helium nuclear reactions (helium fusion) produce primarily

Correct AnswerverifiedShow Answer

A white dwarf star is at what stage of its evolution?

Correct AnswerverifiedShow Answer

How much brighter than its main-sequence luminosity will a Sunlike star become at the asymptotic giant branch (AGB) phase of its life?

Correct AnswerverifiedShow Answer

What is the source of MOST of the heavy elements on Earth and in human bodies?

Correct AnswerverifiedShow Answer

For a massive star (e.g., 25 solar masses) , core hydrogen fusion lasts for several million years. In contrast, the final stage of fusion, core silicon fusion lasts for only about

Correct AnswerverifiedShow Answer

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