Question 1

What must occur for an object to be considered a main-sequence star?

Accepted Answer

A)  Hydrostatic equilibrium ends. 
B)  Nuclear fusion reactions in the core begin. 
C)  Helium flash occurs in the core. 
D)  Gravitational contraction begins. 
A)  Hydrostatic equilibrium ends. 
B)  Nuclear fusion reactions in the core begin. 
C)  Helium flash occurs in the core. 
D)  Gravitational contraction begins.

Question 2

What does solving equations on a computer have to do with making a stellar model?

Accepted Answer

A)  The equations apply the laws of stellar structure at locations within the star. 
B)  Equations can describe the H-R diagram and a star's location on it. 
C)  The mass-luminosity equation tells you how to find a star's luminosity given its mass. 
D)  Equations are used to model the nuclear reactions inside a star. 
A)  The equations apply the laws of stellar structure at locations within the star. 
B)  Equations can describe the H-R diagram and a star's location on it. 
C)  The mass-luminosity equation tells you how to find a star's luminosity given its mass. 
D)  Equations are used to model the nuclear reactions inside a star.

Question 3

How does the temperature inside a star determine how energy flows inside it?

Accepted Answer

A)  The radiation rate depends on temperature. 
B)  The dependence of opacity on temperature makes convection happen. 
C)  The dependence of opacity on temperature makes conduction happen. 
D)  The temperature determines how much energy is produced at each layer. 
A)  The radiation rate depends on temperature. 
B)  The dependence of opacity on temperature makes convection happen. 
C)  The dependence of opacity on temperature makes conduction happen. 
D)  The temperature determines how much energy is produced at each layer.

Question 4

-Refer to the H-R diagram. Which point represents a star in which the CNO cycle is occurring?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
A)  1 
B)  2 
C)  3 
D)  4

Question 5

Stars of one solar mass produce their energy by the set of nuclear reactions called the CNO cycle.

Accepted Answer

A) True 
 B)False

Question 6

Some massive stars only live a few million years.

Accepted Answer

A) True 
 B)False

Question 7

The Orion region contains young main-sequence stars and an emission nebula, but the original molecular cloud they formed out of has been dispersed.

Accepted Answer

A) True 
 B)False

Question 8

Why do nuclear fusion reactions only take place in the interior of a star (rather than at the surface)?

Accepted Answer

A)  The magnetic fields are strongest there. 
B)  The temperature and density are highest in the centre. 
C)  The core is the only place where hydrogen is found. 
D)  The strong nuclear force is only active in the centres of stars. 
A)  The magnetic fields are strongest there. 
B)  The temperature and density are highest in the centre. 
C)  The core is the only place where hydrogen is found. 
D)  The strong nuclear force is only active in the centres of stars.

Question 9

Higher mass stars evolve more slowly to the main sequence than lower mass stars.

Accepted Answer

A) True 
 B)False

Question 10

What happens in the proton-proton chain?

Accepted Answer

A)  Two protons are fused to make a helium nucleus. 
B)  Three protons are fused to make a lithium nucleus. 
C)  A helium nucleus is split into four protons. 
D)  Four protons are fused to make a helium nucleus. 
A)  Two protons are fused to make a helium nucleus. 
B)  Three protons are fused to make a lithium nucleus. 
C)  A helium nucleus is split into four protons. 
D)  Four protons are fused to make a helium nucleus.

Question 11

Energy transport by ____________________ is important when photons cannot readily travel through a gas.

Accepted Answer

The answer of Energy transport by ____________________ is important when...

Question 12

What is the source of the pink glow within the Great Nebula in Orion?

Accepted Answer

A)  a Herbig-Haro object 
B)  a reflection nebula made of dust 
C)  young low-mass stars 
D)  an emission nebula made of gas 
A)  a Herbig-Haro object 
B)  a reflection nebula made of dust 
C)  young low-mass stars 
D)  an emission nebula made of gas

Question 13

What is the term for the process that fuses hydrogen into helium in the cores of massive main-sequence stars?

Accepted Answer

A)  the CNO cycle 
B)  the proton-proton chain 
C)  hydrostatic equilibrium 
D)  the neutrino process 
A)  the CNO cycle 
B)  the proton-proton chain 
C)  hydrostatic equilibrium 
D)  the neutrino process

Question 14

As a star begins to form, what is its primary energy source?

Accepted Answer

A)  nuclear fusion 
B)  nuclear fission 
C)  gravitational potential energy 
D)  magnetic fields 
A)  nuclear fusion 
B)  nuclear fission 
C)  gravitational potential energy 
D)  magnetic fields

Question 15

Why are protostars difficult to observe?

Accepted Answer

A)  The protostar stage is very long. 
B)  They are all so far away that the light hasn't reached us yet. 
C)  Most of their radiation is in the form of X-rays. 
D)  They are surrounded by cocoons of gas and dust. 
A)  The protostar stage is very long. 
B)  They are all so far away that the light hasn't reached us yet. 
C)  Most of their radiation is in the form of X-rays. 
D)  They are surrounded by cocoons of gas and dust.

Question 16

A(n) ____________________ is a cool, dense cloud of dust and gas that is undergoing gravitational contraction.

Accepted Answer

The answer of A(n) ____________________ is a cool, dense cloud...

Question 17

What would happen if the nuclear reactions in a star began to produce too much energy?

Accepted Answer

A)  The star would shrink. 
B)  The star would expand. 
C)  The star would collapse. 
D)  Nothing would happen. 
A)  The star would shrink. 
B)  The star would expand. 
C)  The star would collapse. 
D)  Nothing would happen.

Question 18

The dust in the interstellar medium can make distant stars look redder than they really are.

Accepted Answer

A) True 
 B)False

Question 19

Which of the following relationships is the key to nuclear reactions in a star's core remaining under control?

Accepted Answer

A)  Luminosity depends on mass. 
B)  Pressure depends on temperature. 
C)  Density depends on mass. 
D)  Weight depends on temperature. 
A)  Luminosity depends on mass. 
B)  Pressure depends on temperature. 
C)  Density depends on mass. 
D)  Weight depends on temperature.

Question 20

What concept explains why both fusion and fission release energy?

Accepted Answer

A)  proton-proton chain energy 
B)  Coulomb barrier energy 
C)  strong force energy 
D)  nuclear binding energy 
A)  proton-proton chain energy 
B)  Coulomb barrier energy 
C)  strong force energy 
D)  nuclear binding energy

What must occur for an object to be considered a main-sequence star?

What does solving equations on a computer have to do with making a stellar model?

How does the temperature inside a star determine how energy flows inside it?

-Refer to the H-R diagram. Which point represents a star in which the CNO cycle is occurring?

Stars of one solar mass produce their energy by the set of nuclear reactions called the CNO cycle.

Some massive stars only live a few million years.

The Orion region contains young main-sequence stars and an emission nebula, but the original molecular cloud they formed out of has been dispersed.

Why do nuclear fusion reactions only take place in the interior of a star (rather than at the surface)?

Higher mass stars evolve more slowly to the main sequence than lower mass stars.

What happens in the proton-proton chain?

Energy transport by ____________________ is important when photons cannot readily travel through a gas.

What is the source of the pink glow within the Great Nebula in Orion?

What is the term for the process that fuses hydrogen into helium in the cores of massive main-sequence stars?

As a star begins to form, what is its primary energy source?

Why are protostars difficult to observe?

A(n) ____________________ is a cool, dense cloud of dust and gas that is undergoing gravitational contraction.

What would happen if the nuclear reactions in a star began to produce too much energy?

The dust in the interstellar medium can make distant stars look redder than they really are.

Which of the following relationships is the key to nuclear reactions in a star's core remaining under control?

What concept explains why both fusion and fission release energy?

The Scale of the Cosmos: Space and Time

Users Guide to the Sky: Patterns and Cycles

The Origin of Modern Astronomy

Astronomical Telescopes and Instruments: Extending Humanitys Vision

The Sun: the Closest Star

The Family of Stars

The Deaths of Stars

The Milky Way Galaxy

Galaxies

Cosmology in the 21st Century

Planet Formation and Exoplanets

Comparative Planetology of the Terrestrial Planets

The Outer Solar System

Life on Other Worlds

Filters

Exam 7: The Structure and Formation of Stars

What must occur for an object to be considered a main-sequence star?

What does solving equations on a computer have to do with making a stellar model?

How does the temperature inside a star determine how energy flows inside it?

-Refer to the H-R diagram. Which point represents a star in which the CNO cycle is occurring?

Stars of one solar mass produce their energy by the set of nuclear reactions called the CNO cycle.

Some massive stars only live a few million years.

The Orion region contains young main-sequence stars and an emission nebula, but the original molecular cloud they formed out of has been dispersed.

Why do nuclear fusion reactions only take place in the interior of a star (rather than at the surface)?

Higher mass stars evolve more slowly to the main sequence than lower mass stars.

What happens in the proton-proton chain?

Energy transport by ____________________ is important when photons cannot readily travel through a gas.

What is the source of the pink glow within the Great Nebula in Orion?

What is the term for the process that fuses hydrogen into helium in the cores of massive main-sequence stars?

As a star begins to form, what is its primary energy source?

Why are protostars difficult to observe?

A(n) ____________________ is a cool, dense cloud of dust and gas that is undergoing gravitational contraction.

What would happen if the nuclear reactions in a star began to produce too much energy?

The dust in the interstellar medium can make distant stars look redder than they really are.

Which of the following relationships is the key to nuclear reactions in a star's core remaining under control?

What concept explains why both fusion and fission release energy?

The Scale of the Cosmos: Space and Time

Users Guide to the Sky: Patterns and Cycles

The Origin of Modern Astronomy

Astronomical Telescopes and Instruments: Extending Humanitys Vision

The Sun: the Closest Star

The Family of Stars

The Deaths of Stars

The Milky Way Galaxy

Galaxies

Cosmology in the 21st Century

Planet Formation and Exoplanets

Comparative Planetology of the Terrestrial Planets

The Outer Solar System

Life on Other Worlds

Filters