Question 1

What is the lifetime on the main sequence of a 2 solar mass star compared to the approximately 10 billion year life of our Sun? Pick the best answer.

Accepted Answer

A)  1.8 10 11 years 
B)  1.8 10 10 years 
C)  1.8 10 9 years 
D)  1.8 10 6 years 
E)  1.8 10 3 years 
A)  1.8 10 11 years 
B)  1.8 10 10 years 
C)  1.8 10 9 years 
D)  1.8 10 6 years 
E)  1.8 10 3 years C

Question 2

____ occurs when most of the material collapsing to form a protostar has fallen into a disk around the star and a strong wind from the warm protostar ejects material from its poles.

Accepted Answer

A)  An emission nebula 
B)  Hydrostatic equilibrium 
C)  The proton-proton chain 
D)  The thermonuclear fusion of hydrogen 
E)  A bipolar outflow 
A)  An emission nebula 
B)  Hydrostatic equilibrium 
C)  The proton-proton chain 
D)  The thermonuclear fusion of hydrogen 
E)  A bipolar outflow E

Question 3

One solar mass stars produce their energy by the set of nuclear reactions called the CNO cycle.

Accepted Answer

A) True 
 B)False  False

Question 4

____ are small luminous nebulae excited by nearby young stars.

Accepted Answer

A)  T Tauri stars 
B)  Herbig-Haro objects 
C)  O associations 
D)  Bok Globule 
E)  Giant molecular clouds 
A)  T Tauri stars 
B)  Herbig-Haro objects 
C)  O associations 
D)  Bok Globule 
E)  Giant molecular clouds

Question 5

The nucleus of the hydrogen atom consists of a single neutron.

Accepted Answer

A) True 
 B)False

Question 6

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 7

Nuclear fusion in stars is controlled by the dependence of density on mass.

Accepted Answer

A) True 
 B)False

Question 8

The creation of ____ require(s) that a young hot star (T 25,000 K) be relatively nearby.

Accepted Answer

A)  Emission nebulae 
B)  HI regions 
C)  Molecular clouds 
D)  The cool gas of the interstellar medium 
E)  21 cm radiation 
A)  Emission nebulae 
B)  HI regions 
C)  Molecular clouds 
D)  The cool gas of the interstellar medium 
E)  21 cm radiation

Question 9

There is a main sequence mass-luminosity relation because

Accepted Answer

A)  helium fusion produces carbon. 
B)  stars expand when they become giants. 
C)  more massive stars support their larger weight by making more energy. 
D)  the helium flash occurs in degenerate matter. 
E)  all stars on the main sequence have about the same radius. 
A)  helium fusion produces carbon. 
B)  stars expand when they become giants. 
C)  more massive stars support their larger weight by making more energy. 
D)  the helium flash occurs in degenerate matter. 
E)  all stars on the main sequence have about the same radius.

Question 10

Why are reflection nebulae blue in color?

Accepted Answer

The answer of Why are reflection nebulae blue in color?...

Question 11

What observations indicate the presence of dust in the interstellar medium?

Accepted Answer

The presence of dust in the interstellar

Question 12

The H-R diagram of a young star cluster shows

Accepted Answer

A)  that high mass stars have not yet reached the main sequence yet. 
B)  that low mass stars have not yet reached the main sequence yet. 
C)  mainly giant stars. 
D)  no stars since none have reached the main sequence yet. 
A)  that high mass stars have not yet reached the main sequence yet. 
B)  that low mass stars have not yet reached the main sequence yet. 
C)  mainly giant stars. 
D)  no stars since none have reached the main sequence yet.

Question 13

Energy flows by radiation or convection inside stars but almost never by conduction.

Accepted Answer

A) True 
 B)False

Question 14

The main sequence has a limit at the lower end because

Accepted Answer

A)  low mass stars form from the interstellar medium very rarely. 
B)  low mass objects are composed primarily of solids, not gases. 
C)  pressure does not depend on temperature in degenerate matter. 
D)  the lower limit represents when the radius of the star would be zero. 
E)  there is a minimum temperature for hydrogen nuclear fusion (the definition of a star). 
A)  low mass stars form from the interstellar medium very rarely. 
B)  low mass objects are composed primarily of solids, not gases. 
C)  pressure does not depend on temperature in degenerate matter. 
D)  the lower limit represents when the radius of the star would be zero. 
E)  there is a minimum temperature for hydrogen nuclear fusion (the definition of a star).

Question 15

____ is the thermonuclear fusion of hydrogen to form helium operating in the cores of massive stars on the main sequence.

Accepted Answer

A)  The CNO cycle 
B)  The proton-proton chain 
C)  Hydrostatic equilibrium 
D)  The neutrino process 
E)  none of the above 
A)  The CNO cycle 
B)  The proton-proton chain 
C)  Hydrostatic equilibrium 
D)  The neutrino process 
E)  none of the above

Question 16

The average star spends ____ of its lifetime on the main sequence.

Accepted Answer

A)  1% 
B)  2% 
C)  10% 
D)  20% 
E)  90% 
A)  1% 
B)  2% 
C)  10% 
D)  20% 
E)  90%

Question 17

Absorption lines due to the interstellar medium indicate that some components of the interstellar medium are cold and of a very low density because

Accepted Answer

A)  the lines are blue shifted. 
B)  the lines are red shifted. 
C)  the lines are extremely broad. 
D)  the lines are extremely narrow. 
E)  the lines are much darker than the stellar lines. 
A)  the lines are blue shifted. 
B)  the lines are red shifted. 
C)  the lines are extremely broad. 
D)  the lines are extremely narrow. 
E)  the lines are much darker than the stellar lines.

Question 18

Why do higher mass stars live shorter lives on the main sequence than lower mass stars?

Accepted Answer

A)  Higher mass stars burn through their nuclear fuel faster. 
B)  Lower mass stars don t get their energy from that same nuclear fusion source as higher mass stars. 
C)  Higher mass stars have less hydrogen fuel to burn. 
D)  Lower mass stars spend a longer time evolving to the main-sequence. 
E)  All of the above are false. 
A)  Higher mass stars burn through their nuclear fuel faster. 
B)  Lower mass stars don t get their energy from that same nuclear fusion source as higher mass stars. 
C)  Higher mass stars have less hydrogen fuel to burn. 
D)  Lower mass stars spend a longer time evolving to the main-sequence. 
E)  All of the above are false.

Question 19

What observations confirm the existence of protostars?

Accepted Answer

There are several observations that conf

Question 20

Absorption lines due to interstellar gas

Accepted Answer

A)  are wider than the lines from stars because the gas is hotter than most stars. 
B)  are more narrow than the lines from stars because the gas has a lower pressure than stars. 
C)  indicate that the interstellar medium contains dust. 
D)  indicate that the interstellar medium is expanding away from the sun. 
E)  none of the above 
A)  are wider than the lines from stars because the gas is hotter than most stars. 
B)  are more narrow than the lines from stars because the gas has a lower pressure than stars. 
C)  indicate that the interstellar medium contains dust. 
D)  indicate that the interstellar medium is expanding away from the sun. 
E)  none of the above

What is the lifetime on the main sequence of a 2 solar mass star compared to the approximately 10 billion year life of our Sun? Pick the best answer.

____ occurs when most of the material collapsing to form a protostar has fallen into a disk around the star and a strong wind from the warm protostar ejects material from its poles.

One solar mass stars produce their energy by the set of nuclear reactions called the CNO cycle.

____ are small luminous nebulae excited by nearby young stars.

The nucleus of the hydrogen atom consists of a single neutron.

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

Nuclear fusion in stars is controlled by the dependence of density on mass.

The creation of ____ require(s) that a young hot star (T 25,000 K) be relatively nearby.

There is a main sequence mass-luminosity relation because

Why are reflection nebulae blue in color?

What observations indicate the presence of dust in the interstellar medium?

The H-R diagram of a young star cluster shows

Energy flows by radiation or convection inside stars but almost never by conduction.

The main sequence has a limit at the lower end because

____ is the thermonuclear fusion of hydrogen to form helium operating in the cores of massive stars on the main sequence.

The average star spends ____ of its lifetime on the main sequence.

Absorption lines due to the interstellar medium indicate that some components of the interstellar medium are cold and of a very low density because

Why do higher mass stars live shorter lives on the main sequence than lower mass stars?

What observations confirm the existence of protostars?

Absorption lines due to interstellar gas

Here and Now

Users Guide to the Sky: Patterns and Cycles

The Origin of Modern Astronomy

Light and Telescopes

Sun Light and Sun Atoms

The Terrestrial Planets

The Outer Solar System

Origins of the Solar System and Extrasolar Planets

The Family of Stars

The Deaths of Stars

The Milky Way Galaxy

Galaxies: Normal and Active

Modern Cosmology

Life on Other Worlds

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Exam 10: Structure and Formation of Stars

What is the lifetime on the main sequence of a 2 solar mass star compared to the approximately 10 billion year life of our Sun? Pick the best answer.

____ occurs when most of the material collapsing to form a protostar has fallen into a disk around the star and a strong wind from the warm protostar ejects material from its poles.

One solar mass stars produce their energy by the set of nuclear reactions called the CNO cycle.

____ are small luminous nebulae excited by nearby young stars.

The nucleus of the hydrogen atom consists of a single neutron.

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

Nuclear fusion in stars is controlled by the dependence of density on mass.

The creation of ____ require(s) that a young hot star (T 25,000 K) be relatively nearby.

There is a main sequence mass-luminosity relation because

Why are reflection nebulae blue in color?

What observations indicate the presence of dust in the interstellar medium?

The H-R diagram of a young star cluster shows

Energy flows by radiation or convection inside stars but almost never by conduction.

The main sequence has a limit at the lower end because

____ is the thermonuclear fusion of hydrogen to form helium operating in the cores of massive stars on the main sequence.

The average star spends ____ of its lifetime on the main sequence.

Absorption lines due to the interstellar medium indicate that some components of the interstellar medium are cold and of a very low density because

Why do higher mass stars live shorter lives on the main sequence than lower mass stars?

What observations confirm the existence of protostars?

Absorption lines due to interstellar gas

Here and Now

Users Guide to the Sky: Patterns and Cycles

The Origin of Modern Astronomy

Light and Telescopes

Sun Light and Sun Atoms

The Terrestrial Planets

The Outer Solar System

Origins of the Solar System and Extrasolar Planets

The Family of Stars

The Deaths of Stars

The Milky Way Galaxy

Galaxies: Normal and Active

Modern Cosmology

Life on Other Worlds

Filters