Question 1

What is a protostar?

Accepted Answer

A)   A contracting sphere of gas produced by the collapse of an interstellar cloud with,as yet,no nuclear reactions occurring in its interior
B)   A shell of gas left behind from the explosion of a star as a supernova
C)   A small,cold,interstellar cloud before it collapses to become a star
D)   A star near the end of its life,just before it explodes as a supernovaE) A) and B)
F) None of the above

Question 2

The stellar remnant that will be left after the Sun ends its main-sequence life is a white dwarf.

Accepted Answer

A) True 
 B)False

Question 3

What "safety valve" operates in the gas of normal (nondegenerate) stars?

Accepted Answer

A)   If the star gets too big,it will collapse into a black hole.
B)   If the stellar gas is suddenly heated,it will expand and cool.
C)   If the pressure gets too high,electrons will combine with protons to relieve the pressure.
D)   If thermonuclear reactions proceed too quickly,the star will run out of fuel before anything drastic happens.E) B) and D)
F) A) and B)

Question 4

When stars enter their red-giant phase,their plot on the H-R Diagram moves down and to the left of the graph.

Accepted Answer

A) True 
 B)False

Question 5

What is the most important factor that determines the point in the Hertzsprung-Russell diagram where a protostar reaches the main sequence?

Accepted Answer

A)   The initial luminosity of the protostar
B)   The size of the interstellar cloud from which the protostar formed
C)   The initial temperature of the protostar
D)   The mass of the protostarE) A) and B)
F) A) and D)

Question 6

Protostars with emission lines as well as absorption lines in their spectra and whose luminosity can change irregularly as they eject material into space are

Accepted Answer

A)   asymptotic giant branch stars.
B)   T Tauri stars.
C)   red-giant stars.
D)   main-sequence stars.E) A) and B)
F) A) and C)

Question 7

The age of a cluster can be found by

Accepted Answer

A)   observing its position in the sky with respect to the Sun.
B)   measuring its speed of motion relative to the Sun.
C)   carrying out a number count of the stars in the cluster.
D)   determining the turnoff point on the main sequence of its H-R diagram.E) C) and D)
F) All of the above

Question 8

What causes the characteristic blue color of a reflection nebula?

Accepted Answer

A)   Scattering of starlight from dust grains within the nebula
B)   Thermal (blackbody) radiation from dust grains heated to high temperatures by stellar UV
C)   Electrons dropping from n = 3 to n = 2 in hydrogen atoms
D)   Electrons dropping from n = 2 to n = 1 in hydrogen atomsE) None of the above
F) C) and D)

Question 9

At what stage of its life does a star pass through the protostar phase?

Accepted Answer

A)   When it is expanding in size as a red giant or supergiant
B)   Wfter all nuclear reactions have ended in its core
C)   Before nuclear reactions begin in its core
D)   While it is converting hydrogen to helium in its coreE) B) and C)
F) C) and D)

Question 10

What are asymptotic giant branch (AGB)stars,and what are their characteristics?

Accepted Answer

Stars in a second red-giant phase at the...

Question 11

Stars spend the majority of their lives

Accepted Answer

A)   creating hydrogen from heavier elements absorbing energy in the process.
B)   creating hydrogen from heavier elements releasing energy in the process.
C)   consuming hydrogen and forging heavier elements absorbing energy in the process.
D)   consuming hydrogen and forging heavier elements releasing energy in the process.E) None of the above
F) C) and D)

Question 12

The distinctive color of a reflection nebula is

Accepted Answer

A)   blue,caused by the preferential scattering of starlight by very small dust grains.
B)   starlight of all colors from cool stars,predominantly in the red part of the spectrum,reflected by ice crystals of water,ammonia,and methane.
C)   a mixture of several specific colors coming from fluorescence of atoms excited by ultraviolet radiation emitted by hot stars.
D)   red,coming from the emission of light from hydrogen gas.E) B) and D)
F) B) and C)

Question 13

What is the difference between dark nebulae,emission nebulae,and reflection nebulae?

Accepted Answer

A dark nebula is so opaque that it block...

Question 14

The space between stars is now known to contain

Accepted Answer

A)   large quantities of dust that absorb light but no gas,either atomic or molecular.
B)   gas,made up of atoms,molecules,and dust particles.
C)   a perfect vacuum.
D)   variable amounts of gas but no dust,because dust forms only in planetary systems near stars.E) All of the above
F) None of the above

Question 15

Stars between 0.4 and 4 solar masses go through two distinct red-giant stages.

Accepted Answer

A) True 
 B)False

Question 16

If one person cannot observe a single star go through its entire life span,how are astronomers able to determine the evolution (birth,life,and death)of stars?

Accepted Answer

Because it is impossible to watch a sing...

Question 17

Population I stars are members of a second stellar generation,whereas Population II stars belong to an older first generation.

Accepted Answer

A) True 
 B)False

Question 18

A reflection nebula is made visible by

Accepted Answer

A)   thermal energy emitted as a continuous spectrum by very hot gas,much like that emitted by a hot body on Earth.
B)   blue light,preferentially scattered by tiny dust grains.
C)   emission lines from hydrogen,which itself has been ionized by UV light from embedded stars.
D)   light from embedded stars,reflected over a wide range of wavelengths toward Earth by crystals of water.E) A) and B)
F) A) and C)

Question 19

The hydrogen in the outer layers of the Sun cannot undergo fusion because the

Accepted Answer

A)   hydrogen in the outer layers is fundamentally different from the hydrogen in the core.
B)   hydrogen in the outer layers is pure,and hydrogen must be mixed with helium,as it is in the core,in order to undergo fusion.
C)   temperature in the outer layers is too low to allow the hydrogen nuclei to come close enough together to undergo fusion.
D)   hydrogen atoms in the surface layers are not ionized,as they are in the core,and ionization is one requirement for nuclear fusion.E) B) and C)
F) B) and D)

Question 20

The farther up and to the left the turnoff point of a cluster of stars plotted on the H-R Diagram is,the

Accepted Answer

A)   older the cluster is.
B)   younger the cluster is.
C)   farther away the cluster is.
D)   closer the cluster is.E) A) and B)
F) All of the above

Exam 11: Inferring Patterns in Star Life Cycles

What is the difference between dark nebulae,emission nebulae,and reflection nebulae?

Correct AnswerverifiedA dark nebula is so opaque that it block...View AnswerShow Answer

When stars enter their red-giant phase,their plot on the H-R Diagram moves down and to the left of the graph.

Correct AnswerverifiedShow Answer

What is the most important factor that determines the point in the Hertzsprung-Russell diagram where a protostar reaches the main sequence?

Correct AnswerverifiedShow Answer

A reflection nebula is made visible by

Correct AnswerverifiedShow Answer

The space between stars is now known to contain

Correct AnswerverifiedShow Answer

The farther up and to the left the turnoff point of a cluster of stars plotted on the H-R Diagram is,the

Correct AnswerverifiedShow Answer

Population I stars are members of a second stellar generation,whereas Population II stars belong to an older first generation.

Correct AnswerverifiedShow Answer

The stellar remnant that will be left after the Sun ends its main-sequence life is a white dwarf.

Correct AnswerverifiedShow Answer

What "safety valve" operates in the gas of normal (nondegenerate) stars?

Correct AnswerverifiedShow Answer

Stars spend the majority of their lives

Correct AnswerverifiedShow Answer

Protostars with emission lines as well as absorption lines in their spectra and whose luminosity can change irregularly as they eject material into space are

Correct AnswerverifiedShow Answer

The hydrogen in the outer layers of the Sun cannot undergo fusion because the

Correct AnswerverifiedShow Answer

The distinctive color of a reflection nebula is

Correct AnswerverifiedShow Answer

At what stage of its life does a star pass through the protostar phase?

Correct AnswerverifiedShow Answer

What is a protostar?

Correct AnswerverifiedShow Answer

Stars between 0.4 and 4 solar masses go through two distinct red-giant stages.

Correct AnswerverifiedShow Answer

The age of a cluster can be found by

Correct AnswerverifiedShow Answer

What causes the characteristic blue color of a reflection nebula?

Correct AnswerverifiedShow Answer

If one person cannot observe a single star go through its entire life span,how are astronomers able to determine the evolution (birth,life,and death)of stars?

Correct AnswerverifiedBecause it is impossible to watch a sing...View AnswerShow Answer

What are asymptotic giant branch (AGB)stars,and what are their characteristics?

Correct AnswerverifiedStars in a second red-giant phase at the...View AnswerShow Answer

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A dark nebula is so opaque that it block...
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Because it is impossible to watch a sing...
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Stars in a second red-giant phase at the...
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