Question 1

What point defines the end of the pre-main-sequence phase of a star's life and the start of the main-sequence phase?

Accepted Answer

A)  The star begins to expand and become a red giant. 
B)  Convection begins in its interior. 
C)  The star stops accreting mass from the interstellar cloud. 
D)  Nuclear reactions begin in its core. 
A)  The star begins to expand and become a red giant. 
B)  Convection begins in its interior. 
C)  The star stops accreting mass from the interstellar cloud. 
D)  Nuclear reactions begin in its core.

Question 2

What are the stars in the upper part of the instability strip called?

Accepted Answer

A)  protostars 
B)  T Tauri stars 
C)  RR Lyrae variables 
D)  Cepheid variables 
A)  protostars 
B)  T Tauri stars 
C)  RR Lyrae variables 
D)  Cepheid variables

Question 3

What is a protostar?

Accepted Answer

A)  sphere of gas after collapse from an interstellar cloud but before nuclear reactions have begun 
B)  small interstellar cloud before it collapses to become a star 
C)  star near the end of its life before it explodes as a supernova 
D)  shell of gas left behind from the explosion of a star as a supernova 
A)  sphere of gas after collapse from an interstellar cloud but before nuclear reactions have begun 
B)  small interstellar cloud before it collapses to become a star 
C)  star near the end of its life before it explodes as a supernova 
D)  shell of gas left behind from the explosion of a star as a supernova

Question 4

The Sun is a member of which one of these stellar groups?

Accepted Answer

A)  Cepheid variables 
B)  Population II 
C)  horizontal-branch stars 
D)  Population I 
A)  Cepheid variables 
B)  Population II 
C)  horizontal-branch stars 
D)  Population I

Question 5

In what type of binary system can the two stars share the same outer atmosphere?

Accepted Answer

A)  detached binary 
B)  semidetached binary 
C)  contact binary 
D)  overcontact binary 
A)  detached binary 
B)  semidetached binary 
C)  contact binary 
D)  overcontact binary

Question 6

The mass of a particular interstellar giant molecular cloud is 2 million solar masses. Approximately what is the mass of the hydrogen in this cloud?

Accepted Answer

A)  40,000 solar masses 
B)  1 million solar masses 
C)  1.5 million solar masses 
D)  1.96 million solar masses 
A)  40,000 solar masses 
B)  1 million solar masses 
C)  1.5 million solar masses 
D)  1.96 million solar masses

Question 7

What are the two MOST abundant elements in the interstellar medium?

Accepted Answer

A)  hydrogen and carbon 
B)  hydrogen and oxygen 
C)  hydrogen and helium 
D)  nitrogen and oxygen 
A)  hydrogen and carbon 
B)  hydrogen and oxygen 
C)  hydrogen and helium 
D)  nitrogen and oxygen

Question 8

A main-sequence star can be no smaller than 0.08 solar mass. The reason is that

Accepted Answer

A)  thermonuclear reactions begin so suddenly in stars of less than 0.08 solar mass that the star is disrupted by an explosion. 
B)  protostars of less than 0.08 solar mass cannot form. 
C)  protostars of less than 0.08 solar mass are not massive enough to contract. 
D)  the temperature in a contracting protostar of less than 0.08 solar mass does not become high enough for nuclear reactions in normal hydrogen to start. 
A)  thermonuclear reactions begin so suddenly in stars of less than 0.08 solar mass that the star is disrupted by an explosion. 
B)  protostars of less than 0.08 solar mass cannot form. 
C)  protostars of less than 0.08 solar mass are not massive enough to contract. 
D)  the temperature in a contracting protostar of less than 0.08 solar mass does not become high enough for nuclear reactions in normal hydrogen to start.

Question 9

The periods of Type I Cepheids and Type II Cepheids are different for stars of the same luminosity. What is the physical difference between these stars that causes the periods to be different?

Accepted Answer

A)  Type II Cepheids are older, having evolved from Type I Cepheids. 
B)  The two types have different metallicities. 
C)  Type I Cepheids are members of binary systems, whereas Type II Cepheids are solitary stars. 
D)  Type II Cepheids have gone through the helium flash, whereas Type I Cepheids have yet to do so. 
A)  Type II Cepheids are older, having evolved from Type I Cepheids. 
B)  The two types have different metallicities. 
C)  Type I Cepheids are members of binary systems, whereas Type II Cepheids are solitary stars. 
D)  Type II Cepheids have gone through the helium flash, whereas Type I Cepheids have yet to do so.

Question 10

Why should the period-luminosity relationship be different for Type I Cepheids and Type II Cepheids?

Accepted Answer

A)  Type II Cepheids are dwarf stars and thus much less luminous than Type II giants. 
B)  Type I Cepheids are metal-rich and thus have more heavy elements in their atmospheres. 
C)  Type II Cepheids are metal-rich and thus have more heavy elements in their atmospheres. 
D)  Type I Cepheids get their energy primarily from hydrogen fusion while Type II Cepheids get their energy primarily from helium fusion. 
A)  Type II Cepheids are dwarf stars and thus much less luminous than Type II giants. 
B)  Type I Cepheids are metal-rich and thus have more heavy elements in their atmospheres. 
C)  Type II Cepheids are metal-rich and thus have more heavy elements in their atmospheres. 
D)  Type I Cepheids get their energy primarily from hydrogen fusion while Type II Cepheids get their energy primarily from helium fusion.

Question 11

What is the best way to estimate the age of a star cluster?

Accepted Answer

A)  Plot the stars on a Hertzsprung-Russell diagram, and see which stars are still on the main sequence. 
B)  Measure the motions of the stars in the cluster, and compare the measurements with theoretical models. 
C)  Measure the heavy element abundance for the stars in the cluster. 
D)  Count the number of T Tauri stars in the cluster. 
A)  Plot the stars on a Hertzsprung-Russell diagram, and see which stars are still on the main sequence. 
B)  Measure the motions of the stars in the cluster, and compare the measurements with theoretical models. 
C)  Measure the heavy element abundance for the stars in the cluster. 
D)  Count the number of T Tauri stars in the cluster.

Question 12

The Pauli exclusion principle

Accepted Answer

A)  prevents high-mass stars from forming in low-mass interstellar clouds. 
B)  sets a limit to the crowding together of electrons in any given small volume of space. 
C)  limits the number of atoms that can become ionized in a star. 
D)  prevents two stars of the same spectral class from occupying the same binary star system. 
A)  prevents high-mass stars from forming in low-mass interstellar clouds. 
B)  sets a limit to the crowding together of electrons in any given small volume of space. 
C)  limits the number of atoms that can become ionized in a star. 
D)  prevents two stars of the same spectral class from occupying the same binary star system.

Question 13

Which of these fall within the typical range of dimensions of a giant molecular cloud in interstellar space?

Accepted Answer

A)  mass of about 1000 solar masses in volume with a diameter of about 1000 ly 
B)  mass of about 1 million solar masses in volume with a diameter of about 100 ly 
C)  mass of about 1 million solar masses in volume with a diameter of about 100 au, about the size of the solar system 
D)  mass of about 1000 solar masses in volume with a diameter of about 100 ly 
A)  mass of about 1000 solar masses in volume with a diameter of about 1000 ly 
B)  mass of about 1 million solar masses in volume with a diameter of about 100 ly 
C)  mass of about 1 million solar masses in volume with a diameter of about 100 au, about the size of the solar system 
D)  mass of about 1000 solar masses in volume with a diameter of about 100 ly

Question 14

If electrons are collectively compressed into a very small volume where the Pauli exclusion principle become important in preventing one electron from occupying space near a second electron, what is the result?

Accepted Answer

A)  The electrons generate a very large pressure to oppose further compression. 
B)  The electrons fall into orbit around one another in mutual pairs that reduce the restricted quantum space, allowing further shrinkage of the star. 
C)  Nuclear fusion occurs between electrons, producing energy and heating the star's core. 
D)  Half the electrons are transformed into antimatter (positrons), which then annihilates electrons, producing a burst of energy and the explosion of the star. 
A)  The electrons generate a very large pressure to oppose further compression. 
B)  The electrons fall into orbit around one another in mutual pairs that reduce the restricted quantum space, allowing further shrinkage of the star. 
C)  Nuclear fusion occurs between electrons, producing energy and heating the star's core. 
D)  Half the electrons are transformed into antimatter (positrons), which then annihilates electrons, producing a burst of energy and the explosion of the star.

Question 15

How is gas distributed in interstellar space?

Accepted Answer

A)  in clumps, concentrated in interstellar clouds 
B)  concentrated in narrow riverlike streams of gas that circle the Galaxy 
C)  uniformly distributed through space 
D)  concentrated around existing stars because of the stars' gravitational pull 
A)  in clumps, concentrated in interstellar clouds 
B)  concentrated in narrow riverlike streams of gas that circle the Galaxy 
C)  uniformly distributed through space 
D)  concentrated around existing stars because of the stars' gravitational pull

Question 16

Star formation takes place in

Accepted Answer

A)  giant molecular clouds. 
B)  globular clusters. 
C)  blue reflection nebulae. 
D)  hot, turbulent gas thrown out in a supernova explosion. 
A)  giant molecular clouds. 
B)  globular clusters. 
C)  blue reflection nebulae. 
D)  hot, turbulent gas thrown out in a supernova explosion.

Question 17

Once astronomers obtain the apparent magnitude for a Cepheid variable star by direct observation and the absolute magnitude from the period-luminosity relation, what do they need to use to find its distance?

Accepted Answer

A)  the H-R diagram (spectroscopic parallax) 
B)  the distance-magnitude relationship 
C)  the Stefan-Boltzmann relationship 
D)  parallax 
A)  the H-R diagram (spectroscopic parallax) 
B)  the distance-magnitude relationship 
C)  the Stefan-Boltzmann relationship 
D)  parallax

Question 18

What causes the characteristic blue color of a reflection nebula?

Accepted Answer

A)  electrons dropping between energy levels n = 3 and n = 2 in hydrogen atoms 
B)  electrons dropping between energy levels n = 2 and n = 1 in hydrogen atoms 
C)  thermal blackbody radiation emitted by the hot gas 
D)  scattering of starlight from dust grains in the nebula 
A)  electrons dropping between energy levels n = 3 and n = 2 in hydrogen atoms 
B)  electrons dropping between energy levels n = 2 and n = 1 in hydrogen atoms 
C)  thermal blackbody radiation emitted by the hot gas 
D)  scattering of starlight from dust grains in the nebula

Question 19

What would one expect to find in the population of stars in a globular cluster?

Accepted Answer

A)  mainly white dwarf stars and dying stars but no faint red stars, red giants, or bright blue stars 
B)  mostly blue giants and supergiants and a few red giant stars, white dwarfs, and dim red stars 
C)  many red giants, white dwarfs, and dim red stars 
D)  stars along the entire main sequence from bright blue to dim red, with no bright red giant stars but significant amounts of dust and gas 
A)  mainly white dwarf stars and dying stars but no faint red stars, red giants, or bright blue stars 
B)  mostly blue giants and supergiants and a few red giant stars, white dwarfs, and dim red stars 
C)  many red giants, white dwarfs, and dim red stars 
D)  stars along the entire main sequence from bright blue to dim red, with no bright red giant stars but significant amounts of dust and gas

Question 20

Thermonuclear reactions convert hydrogen into helium in the core of a star during which phase of a star's life?

Accepted Answer

A)  main-sequence phase 
B)  protostar phase 
C)  horizontal-branch phase 
D)  as the star moves up the red giant branch for the first time 
A)  main-sequence phase 
B)  protostar phase 
C)  horizontal-branch phase 
D)  as the star moves up the red giant branch for the first time

What point defines the end of the pre-main-sequence phase of a star's life and the start of the main-sequence phase?

What are the stars in the upper part of the instability strip called?

What is a protostar?

The Sun is a member of which one of these stellar groups?

In what type of binary system can the two stars share the same outer atmosphere?

The mass of a particular interstellar giant molecular cloud is 2 million solar masses. Approximately what is the mass of the hydrogen in this cloud?

What are the two MOST abundant elements in the interstellar medium?

A main-sequence star can be no smaller than 0.08 solar mass. The reason is that

The periods of Type I Cepheids and Type II Cepheids are different for stars of the same luminosity. What is the physical difference between these stars that causes the periods to be different?

Why should the period-luminosity relationship be different for Type I Cepheids and Type II Cepheids?

What is the best way to estimate the age of a star cluster?

The Pauli exclusion principle

Which of these fall within the typical range of dimensions of a giant molecular cloud in interstellar space?

If electrons are collectively compressed into a very small volume where the Pauli exclusion principle become important in preventing one electron from occupying space near a second electron, what is the result?

How is gas distributed in interstellar space?

Star formation takes place in

Once astronomers obtain the apparent magnitude for a Cepheid variable star by direct observation and the absolute magnitude from the period-luminosity relation, what do they need to use to find its distance?

What causes the characteristic blue color of a reflection nebula?

What would one expect to find in the population of stars in a globular cluster?

Thermonuclear reactions convert hydrogen into helium in the core of a star during which phase of a star's life?

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

What point defines the end of the pre-main-sequence phase of a star's life and the start of the main-sequence phase?

What are the stars in the upper part of the instability strip called?

What is a protostar?

The Sun is a member of which one of these stellar groups?

In what type of binary system can the two stars share the same outer atmosphere?

The mass of a particular interstellar giant molecular cloud is 2 million solar masses. Approximately what is the mass of the hydrogen in this cloud?

What are the two MOST abundant elements in the interstellar medium?

A main-sequence star can be no smaller than 0.08 solar mass. The reason is that

The periods of Type I Cepheids and Type II Cepheids are different for stars of the same luminosity. What is the physical difference between these stars that causes the periods to be different?

Why should the period-luminosity relationship be different for Type I Cepheids and Type II Cepheids?

What is the best way to estimate the age of a star cluster?

The Pauli exclusion principle

Which of these fall within the typical range of dimensions of a giant molecular cloud in interstellar space?

If electrons are collectively compressed into a very small volume where the Pauli exclusion principle become important in preventing one electron from occupying space near a second electron, what is the result?

How is gas distributed in interstellar space?

Star formation takes place in

Once astronomers obtain the apparent magnitude for a Cepheid variable star by direct observation and the absolute magnitude from the period-luminosity relation, what do they need to use to find its distance?

What causes the characteristic blue color of a reflection nebula?

What would one expect to find in the population of stars in a globular cluster?

Thermonuclear reactions convert hydrogen into helium in the core of a star during which phase of a star's life?

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