Question 1

A dark nebula is a large cloud of dust grains that is so opaque that it blocks any visible light coming from the stars behind it.

Accepted Answer

A) True 
 B)False  True

Question 2

Since the Sun started its sustained thermonuclear reactions in the core,its diameter has tripled in size.

Accepted Answer

A) True 
 B)False  False

Question 3

What is one possible explanation for the double-lobed shape of some planetary nebulae?

Accepted Answer

The star ejects a doughnut-shaped cloud of gas and dust from its equator.The star then ejects visible gas from its entire surface and then the doughnut channels the ejected gas into two oppositely directed streams creating an hourglass,or double-lobed,shape.

Question 4

Over which of the following stages of stellar evolution does the radius of a star remain approximately constant?

Accepted Answer

A)  Birth and initial formation 
B)  Red-giant phase 
C)  Asymptotic giant branch phase 
D)  Main-sequence phase 
A)  Birth and initial formation 
B)  Red-giant phase 
C)  Asymptotic giant branch phase 
D)  Main-sequence phase

Question 5

Stars join the main-sequence group when they begin hydrogen fusion in their cores.They leave the main-sequence group and become giant stars when their core hydrogen is depleted.

Accepted Answer

A) True 
 B)False

Question 6

Which of the following statements about the rate of stellar evolution is TRUE?

Accepted Answer

A)  The more massive the original star,the faster the evolution. 
B)  Star mass has no bearing upon stellar evolution because all stars evolve at the same rate,controlled by nuclear fusion and core temperature. 
C)  The chemical makeup of the original nebula is the major factor in deciding the rate of evolution. 
D)  The more massive the original star,the slower the evolution because there is more material for thermonuclear burning. 
A)  The more massive the original star,the faster the evolution. 
B)  Star mass has no bearing upon stellar evolution because all stars evolve at the same rate,controlled by nuclear fusion and core temperature. 
C)  The chemical makeup of the original nebula is the major factor in deciding the rate of evolution. 
D)  The more massive the original star,the slower the evolution because there is more material for thermonuclear burning.

Question 7

Our Sun will end its life by becoming a

Accepted Answer

A)  black hole. 
B)  white dwarf. 
C)  molecular cloud. 
D)  pulsar. 
A)  black hole. 
B)  white dwarf. 
C)  molecular cloud. 
D)  pulsar.

Question 8

Why are the majority of stars in the sky in the main-sequence phase of their lives?

Accepted Answer

A)  This is the longest-lasting phase in each star's life. 
B)  Most stars die at the end of the main-sequence phase. 
C)  This is the only phase that is common to all stars. 
D)  Most stars in the sky were created at about the same time,so they are all in the same phase of their lives. 
A)  This is the longest-lasting phase in each star's life. 
B)  Most stars die at the end of the main-sequence phase. 
C)  This is the only phase that is common to all stars. 
D)  Most stars in the sky were created at about the same time,so they are all in the same phase of their lives.

Question 9

What is a red giant?

Accepted Answer

A)  A large,red star burning hydrogen into helium in its core 
B)  A protostar in the "upper right" part of the Hertzsprung-Russell diagram 
C)  A large emission nebula 
D)  A star burning hydrogen into helium in a shell around the core 
A)  A large,red star burning hydrogen into helium in its core 
B)  A protostar in the "upper right" part of the Hertzsprung-Russell diagram 
C)  A large emission nebula 
D)  A star burning hydrogen into helium in a shell around the core

Question 10

A helium flash occurs in the cores of all stars

Accepted Answer

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

Question 11

Degeneracy occurs when

Accepted Answer

A)  magnetic fields inhibit the motion of charged particles in sunspots. 
B)  solar wind particles ionize atoms in Earth's upper atmosphere. 
C)  thermonuclear reactions halt the contraction of a protostar. 
D)  electrons inside a star resist being pushed closer together than a certain limit. 
A)  magnetic fields inhibit the motion of charged particles in sunspots. 
B)  solar wind particles ionize atoms in Earth's upper atmosphere. 
C)  thermonuclear reactions halt the contraction of a protostar. 
D)  electrons inside a star resist being pushed closer together than a certain limit.

Question 12

The event that follows the asymptotic giant branch (AGB)phase in the life of a low-mass star is

Accepted Answer

A)  the ejection of a planetary nebula. 
B)  core collapse and a supernova explosion. 
C)  helium flash and the start of helium burning in the core. 
D)  the onset of hydrogen burning in the core. 
A)  the ejection of a planetary nebula. 
B)  core collapse and a supernova explosion. 
C)  helium flash and the start of helium burning in the core. 
D)  the onset of hydrogen burning in the core.

Question 13

A nebula that emits its own light with the characteristic emission line spectrum similar to that of a hot,thin gas is called a reflection nebula.

Accepted Answer

A) True 
 B)False

Question 14

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

Accepted Answer

A)  Convection begins in its interior. 
B)  The star stops accreting mass from the interstellar cloud. 
C)  The star begins to expand to become a red supergiant. 
D)  The nuclear reactions in its core allow it to gain hydrostatic equilibrium. 
A)  Convection begins in its interior. 
B)  The star stops accreting mass from the interstellar cloud. 
C)  The star begins to expand to become a red supergiant. 
D)  The nuclear reactions in its core allow it to gain hydrostatic equilibrium.

Question 15

The smallest mass that a main-sequence star can have is about 0.08 solar mass.The reason for this is that

Accepted Answer

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

Question 16

How can the death of a large star,as in a supernova explosion,help create new stars?

Accepted Answer

The supersonic motion of the s

Question 17

The end of the life of a red dwarf star is predicted to be a sphere of almost pure helium,but we have not detected any of these.What do we believe is the reason?

Accepted Answer

A)  These helium stars are very dim and consequently hard to detect. 
B)  There are very few red dwarfs,so their end products are expected to be rare. 
C)  The evolution rate for red dwarfs is so slow that none has yet evolved to its end stage. 
D)  Helium is a relatively light material,so these helium spheres are expected to dissipate in a short time. 
A)  These helium stars are very dim and consequently hard to detect. 
B)  There are very few red dwarfs,so their end products are expected to be rare. 
C)  The evolution rate for red dwarfs is so slow that none has yet evolved to its end stage. 
D)  Helium is a relatively light material,so these helium spheres are expected to dissipate in a short time.

Question 18

When protostars are FIRST formed from the interstellar medium,they are usually

Accepted Answer

A)  detected easily because their light ionizes the surrounding interstellar gas,forming H II regions. 
B)  very bright in ultraviolet light due to numerous flares (like solar flares but hotter and brighter). 
C)  hidden from sight by dust clouds that emit infrared radiation. 
D)  detected by emission lines in their visible spectra,emitted by gas being blown off their surfaces into space. 
A)  detected easily because their light ionizes the surrounding interstellar gas,forming H II regions. 
B)  very bright in ultraviolet light due to numerous flares (like solar flares but hotter and brighter). 
C)  hidden from sight by dust clouds that emit infrared radiation. 
D)  detected by emission lines in their visible spectra,emitted by gas being blown off their surfaces into space.

Question 19

What is the Chandrasekhar limit and what does it mean for stellar evolution?

Accepted Answer

This is the theoretical limit to how mas

Question 20

Prior to reaching the main sequence,a protostar's energy comes mostly from

Accepted Answer

A)  gravitation. 
B)  nuclear fusion. 
C)  nuclear fission. 
D)  natural radioactivity. 
A)  gravitation. 
B)  nuclear fusion. 
C)  nuclear fission. 
D)  natural radioactivity.

A dark nebula is a large cloud of dust grains that is so opaque that it blocks any visible light coming from the stars behind it.

Since the Sun started its sustained thermonuclear reactions in the core,its diameter has tripled in size.

What is one possible explanation for the double-lobed shape of some planetary nebulae?

Over which of the following stages of stellar evolution does the radius of a star remain approximately constant?

Stars join the main-sequence group when they begin hydrogen fusion in their cores.They leave the main-sequence group and become giant stars when their core hydrogen is depleted.

Which of the following statements about the rate of stellar evolution is TRUE?

Our Sun will end its life by becoming a

Why are the majority of stars in the sky in the main-sequence phase of their lives?

What is a red giant?

A helium flash occurs in the cores of all stars

Degeneracy occurs when

The event that follows the asymptotic giant branch (AGB)phase in the life of a low-mass star is

A nebula that emits its own light with the characteristic emission line spectrum similar to that of a hot,thin gas is called a reflection nebula.

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

The smallest mass that a main-sequence star can have is about 0.08 solar mass.The reason for this is that

How can the death of a large star,as in a supernova explosion,help create new stars?

The end of the life of a red dwarf star is predicted to be a sphere of almost pure helium,but we have not detected any of these.What do we believe is the reason?

When protostars are FIRST formed from the interstellar medium,they are usually

What is the Chandrasekhar limit and what does it mean for stellar evolution?

Prior to reaching the main sequence,a protostar's energy comes mostly from

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

Predicting the Violent End of the Largest Stars

Exploring Our Galaxy

Investigating Other Galaxies

Observing the Evolution of the Universe

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Exam 11: Inferring Patterns in Star Life Cycles

A dark nebula is a large cloud of dust grains that is so opaque that it blocks any visible light coming from the stars behind it.

Since the Sun started its sustained thermonuclear reactions in the core,its diameter has tripled in size.

What is one possible explanation for the double-lobed shape of some planetary nebulae?

Over which of the following stages of stellar evolution does the radius of a star remain approximately constant?

Stars join the main-sequence group when they begin hydrogen fusion in their cores.They leave the main-sequence group and become giant stars when their core hydrogen is depleted.

Which of the following statements about the rate of stellar evolution is TRUE?

Our Sun will end its life by becoming a

Why are the majority of stars in the sky in the main-sequence phase of their lives?

What is a red giant?

A helium flash occurs in the cores of all stars

Degeneracy occurs when

The event that follows the asymptotic giant branch (AGB)phase in the life of a low-mass star is

A nebula that emits its own light with the characteristic emission line spectrum similar to that of a hot,thin gas is called a reflection nebula.

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

The smallest mass that a main-sequence star can have is about 0.08 solar mass.The reason for this is that

How can the death of a large star,as in a supernova explosion,help create new stars?

The end of the life of a red dwarf star is predicted to be a sphere of almost pure helium,but we have not detected any of these.What do we believe is the reason?

When protostars are FIRST formed from the interstellar medium,they are usually

What is the Chandrasekhar limit and what does it mean for stellar evolution?

Prior to reaching the main sequence,a protostar's energy comes mostly from

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

Predicting the Violent End of the Largest Stars

Exploring Our Galaxy

Investigating Other Galaxies

Observing the Evolution of the Universe

Filters