Question 1

How hot does the core of a star have to be for helium burning to begin?

Accepted Answer

A)  100 million K 
B)  1 billion K 
C)  1 million K 
D)  10 million K 
A)  100 million K 
B)  1 billion K 
C)  1 million K 
D)  10 million K

Question 2

Which of these do NOT characterize Cepheids and RR Lyrae stars?

Accepted Answer

A)  giants 
B)  unstable 
C)  supernova remnants 
D)  variable 
A)  giants 
B)  unstable 
C)  supernova remnants 
D)  variable

Question 3

Which stars undergo a helium flash in their cores?

Accepted Answer

A)  stars of less than 2 solar masses 
B)  stars that contain helium 
C)  stars of more than 2 solar masses 
D)  stars that have become red giants 
A)  stars of less than 2 solar masses 
B)  stars that contain helium 
C)  stars of more than 2 solar masses 
D)  stars that have become red giants

Question 4

When a variable star periodically changes its luminosity, many of its properties also change. Which of these does NOT change?

Accepted Answer

A)  temperature 
B)  radial surface speed 
C)  size 
D)  rotation rate 
A)  temperature 
B)  radial surface speed 
C)  size 
D)  rotation rate

Question 5

The main-sequence lifetime of a star with half the mass of the Sun

Accepted Answer

A)  could be longer or shorter than that of the Sun; more information is required to determine the length of its lifetime. 
B)  is longer than that of the Sun. 
C)  is the same as that of the Sun because mass does not affect the lifetime of a star. 
D)  is shorter than that of the Sun. 
A)  could be longer or shorter than that of the Sun; more information is required to determine the length of its lifetime. 
B)  is longer than that of the Sun. 
C)  is the same as that of the Sun because mass does not affect the lifetime of a star. 
D)  is shorter than that of the Sun.

Question 6

In a group of stars with a range of masses, stars with different mass

Accepted Answer

A)  leave the main sequence of the Hertzsprung-Russell diagram at different times after their birth. 
B)  have about the same age, as massive stars burn their fuel more rapidly than low-mass stars. 
C)  all go through the supernova phase of evolution at varying times after their births. 
D)  all pass, at some stage in their evolution, through one particular point on the Hertzsprung-Russell diagram, occupied at present by the Sun. 
A)  leave the main sequence of the Hertzsprung-Russell diagram at different times after their birth. 
B)  have about the same age, as massive stars burn their fuel more rapidly than low-mass stars. 
C)  all go through the supernova phase of evolution at varying times after their births. 
D)  all pass, at some stage in their evolution, through one particular point on the Hertzsprung-Russell diagram, occupied at present by the Sun.

Question 7

Two close binary stars exchange mass. Which of these does NOT describe a possible outcome of such a mass exchange?

Accepted Answer

A)  The star that was originally smaller can become the larger of the two. 
B)  An accretion disk can be formed around one of the stars, which can almost block it from view. 
C)  One of the stars can begin to spin so rapidly that its shape will be distorted. 
D)  The two stars can merge to form a single star and then fly apart to form two wholly new stars. 
A)  The star that was originally smaller can become the larger of the two. 
B)  An accretion disk can be formed around one of the stars, which can almost block it from view. 
C)  One of the stars can begin to spin so rapidly that its shape will be distorted. 
D)  The two stars can merge to form a single star and then fly apart to form two wholly new stars.

Question 8

How do astronomers know that globular clusters are very old?

Accepted Answer

A)  Globular clusters do not contain any red giant stars. 
B)  There are no main-sequence stars in globular clusters. 
C)  The stars in a globular cluster have a high abundance of heavy elements. 
D)  There are no massive main-sequence stars in globular clusters. 
A)  Globular clusters do not contain any red giant stars. 
B)  There are no main-sequence stars in globular clusters. 
C)  The stars in a globular cluster have a high abundance of heavy elements. 
D)  There are no massive main-sequence stars in globular clusters.

Question 9

What are the products of helium burning in a star?

Accepted Answer

A)  magnesium and silicon 
B)  nitrogen and oxygen 
C)  carbon and oxygen 
D)  hydrogen and lithium 
A)  magnesium and silicon 
B)  nitrogen and oxygen 
C)  carbon and oxygen 
D)  hydrogen and lithium

Question 10

A degenerate-electron gas, which occurs in the core of a red giant star, lacks the "safety valve" of a normal gas because a rise in

Accepted Answer

A)  pressure releases more electrons, thus increasing the pressure further. 
B)  pressure reduces the number of electrons, causing the core to collapse. 
C)  temperature does not change the pressure, so the gas does not expand and cool. 
D)  temperature lowers the pressure, causing the star to contract. 
A)  pressure releases more electrons, thus increasing the pressure further. 
B)  pressure reduces the number of electrons, causing the core to collapse. 
C)  temperature does not change the pressure, so the gas does not expand and cool. 
D)  temperature lowers the pressure, causing the star to contract.

Question 11

The Pistol in Sagittarius is one of the most massive known stars. But it has lost much of its original 200 solar masses. How long is the entire mass-loss process estimated to take?

Accepted Answer

A)  an explosion lasting a few seconds 
B)  hundreds of millions of years 
C)  a few million years 
D)  a billion years 
A)  an explosion lasting a few seconds 
B)  hundreds of millions of years 
C)  a few million years 
D)  a billion years

Question 12

A protostar eventually becomes a pre-main-sequence star. Which of these statements does NOT characterize the transition?

Accepted Answer

A)  In the pre-main-sequence star, the rate of collapse slows. 
B)  In the pre-main-sequence star, the core temperature is greater. 
C)  The pre-main-sequence star is larger. 
D)  The pre-main-sequence star immediately ejects its outer shell of gas and dust. 
A)  In the pre-main-sequence star, the rate of collapse slows. 
B)  In the pre-main-sequence star, the core temperature is greater. 
C)  The pre-main-sequence star is larger. 
D)  The pre-main-sequence star immediately ejects its outer shell of gas and dust.

Question 13

Which of these mechanisms is NOT thought to be significant in the formation of new stars in the interstellar medium?

Accepted Answer

A)  heating of an interstellar cloud by concentrated beams of neutrinos from nearby stars 
B)  compression of cold interstellar gas by radiation pressure from light from very bright stars 
C)  condensation of matter by the shock wave from a nearby supernova 
D)  collision of two cold interstellar clouds 
A)  heating of an interstellar cloud by concentrated beams of neutrinos from nearby stars 
B)  compression of cold interstellar gas by radiation pressure from light from very bright stars 
C)  condensation of matter by the shock wave from a nearby supernova 
D)  collision of two cold interstellar clouds

Question 14

A low-mass red dwarf (0.08 M < M < 0.4 M) will eventually NOT become

Accepted Answer

A)  a red giant. 
B)  a brown dwarf. 
C)  a white dwarf. 
D)  a red giant, a brown dwarf, or a white dwarf. 
A)  a red giant. 
B)  a brown dwarf. 
C)  a white dwarf. 
D)  a red giant, a brown dwarf, or a white dwarf.

Question 15

When is electron degeneracy pressure important in a star like the Sun?

Accepted Answer

A)  just before the start of helium burning in the core 
B)  during core hydrogen burning 
C)  in a Cepheid variable that is burning helium in its core 
D)  in a protostar evolving toward the main sequence 
A)  just before the start of helium burning in the core 
B)  during core hydrogen burning 
C)  in a Cepheid variable that is burning helium in its core 
D)  in a protostar evolving toward the main sequence

Question 16

Which of these easily observed molecular species is used as a tracer for the fundamental but difficult to observe H2 molecules in giant molecular clouds?

Accepted Answer

A)  hydroxyl (OH) 
B)  water vapor (H2O) 
C)  carbon dioxide (CO2) 
D)  carbon monoxide (CO) 
A)  hydroxyl (OH) 
B)  water vapor (H2O) 
C)  carbon dioxide (CO2) 
D)  carbon monoxide (CO)

Question 17

Parts of a supernova remnant become visible

Accepted Answer

A)  because of radioactive elements that were created in the supernova and carried along with the remnant. 
B)  when large hot stars form within the gas and dust of the remnant and emit radiation, which excites the remaining gas. 
C)  when they collide with other clouds of gas and dust. 
D)  when they interact with the galaxy's strong magnetic field. 
A)  because of radioactive elements that were created in the supernova and carried along with the remnant. 
B)  when large hot stars form within the gas and dust of the remnant and emit radiation, which excites the remaining gas. 
C)  when they collide with other clouds of gas and dust. 
D)  when they interact with the galaxy's strong magnetic field.

Question 18

When a star consumes all of the energy it can from hydrogen fusion in its core, the next long-term energy-producing phase is

Accepted Answer

A)  helium fusion in the core. 
B)  helium fusion in a shell around the core. 
C)  hydrogen fusion in a shell around the core. 
D)  gravitational energy released in a Kelvin-Helmholtz condensation. 
A)  helium fusion in the core. 
B)  helium fusion in a shell around the core. 
C)  hydrogen fusion in a shell around the core. 
D)  gravitational energy released in a Kelvin-Helmholtz condensation.

Question 19

What is a protostar called in the stage after it has finished accreting mass?

Accepted Answer

A)  white dwarf 
B)  red giant (or supergiant) 
C)  pre-main-sequence star 
D)  main-sequence star 
A)  white dwarf 
B)  red giant (or supergiant) 
C)  pre-main-sequence star 
D)  main-sequence star

Question 20

Which of these statements about a globular cluster is NOT true?

Accepted Answer

A)  A globular cluster has a round shape. 
B)  A globular cluster can contain up to 1 million stars. 
C)  A globular cluster contains many main-sequence stars. 
D)  A globular cluster contains both high- and low-mass stars on the main sequence. 
A)  A globular cluster has a round shape. 
B)  A globular cluster can contain up to 1 million stars. 
C)  A globular cluster contains many main-sequence stars. 
D)  A globular cluster contains both high- and low-mass stars on the main sequence.

How hot does the core of a star have to be for helium burning to begin?

Which of these do NOT characterize Cepheids and RR Lyrae stars?

Which stars undergo a helium flash in their cores?

When a variable star periodically changes its luminosity, many of its properties also change. Which of these does NOT change?

The main-sequence lifetime of a star with half the mass of the Sun

In a group of stars with a range of masses, stars with different mass

Two close binary stars exchange mass. Which of these does NOT describe a possible outcome of such a mass exchange?

How do astronomers know that globular clusters are very old?

What are the products of helium burning in a star?

A degenerate-electron gas, which occurs in the core of a red giant star, lacks the "safety valve" of a normal gas because a rise in

The Pistol in Sagittarius is one of the most massive known stars. But it has lost much of its original 200 solar masses. How long is the entire mass-loss process estimated to take?

A protostar eventually becomes a pre-main-sequence star. Which of these statements does NOT characterize the transition?

Which of these mechanisms is NOT thought to be significant in the formation of new stars in the interstellar medium?

A low-mass red dwarf (0.08 M < M < 0.4 M) will eventually NOT become

When is electron degeneracy pressure important in a star like the Sun?

Which of these easily observed molecular species is used as a tracer for the fundamental but difficult to observe H₂ molecules in giant molecular clouds?

Parts of a supernova remnant become visible

When a star consumes all of the energy it can from hydrogen fusion in its core, the next long-term energy-producing phase is

What is a protostar called in the stage after it has finished accreting mass?

Which of these statements about a globular cluster is NOT true?

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Atomic Physics and Spectra

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

Characterizing Stars

The Death of Stars

Black Holes: Matters of Gravity

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Cosmology

Astrobiology

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Exam 13: The Lives of Stars From Birth Through Middle Age

How hot does the core of a star have to be for helium burning to begin?

Which of these do NOT characterize Cepheids and RR Lyrae stars?

Which stars undergo a helium flash in their cores?

When a variable star periodically changes its luminosity, many of its properties also change. Which of these does NOT change?

The main-sequence lifetime of a star with half the mass of the Sun

In a group of stars with a range of masses, stars with different mass

Two close binary stars exchange mass. Which of these does NOT describe a possible outcome of such a mass exchange?

How do astronomers know that globular clusters are very old?

What are the products of helium burning in a star?

A degenerate-electron gas, which occurs in the core of a red giant star, lacks the "safety valve" of a normal gas because a rise in

The Pistol in Sagittarius is one of the most massive known stars. But it has lost much of its original 200 solar masses. How long is the entire mass-loss process estimated to take?

A protostar eventually becomes a pre-main-sequence star. Which of these statements does NOT characterize the transition?

Which of these mechanisms is NOT thought to be significant in the formation of new stars in the interstellar medium?

A low-mass red dwarf (0.08 M < M < 0.4 M) will eventually NOT become

When is electron degeneracy pressure important in a star like the Sun?

Which of these easily observed molecular species is used as a tracer for the fundamental but difficult to observe H2 molecules in giant molecular clouds?

Parts of a supernova remnant become visible

When a star consumes all of the energy it can from hydrogen fusion in its core, the next long-term energy-producing phase is

What is a protostar called in the stage after it has finished accreting mass?

Which of these statements about a globular cluster is NOT true?

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Atomic Physics and Spectra

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

Characterizing Stars

The Death of Stars

Black Holes: Matters of Gravity

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Cosmology

Astrobiology

Filters

Which of these easily observed molecular species is used as a tracer for the fundamental but difficult to observe H₂ molecules in giant molecular clouds?