Question 1

Consider a 1 M⨀ star's journey up the red giant branch.Its luminosity will change from 10 L⨀ to nearly 1,000 L⨀.How will its temperature and radius change as the star ascends? (Recall that L ∝ R2T4. )

Accepted Answer

The red giant star's temperature will essentially remain constant at a value 1000 K less than it was on the main sequence due to the formation of H⁻ ions in the stellar atmosphere.Thus,if its luminosity changes by a factor of 1,000/10 = 100,then the radius will change by 100¹^⁄² = 10.

Question 2

If an 0.8 M⨀ white dwarf could accrete matter from a binary companion at a rate of 10−9 M⨀/yr,how long would it take before it exploded as a Type I supernova?

Accepted Answer

A)  600 thousand years
B)  20 million years
C)  200 million years
D)  600 million years
E)  1 billion yearsF) A) and E)
G) A) and C)

Question 3

Using this diagram,identify the star with the smallest radius.

Accepted Answer

A)  star A
B)  star B
C)  star C
D)  star D
E)  star EF) C) and E)
G) B) and E)

Question 4

Asymptotic giant-branch stars have _________ luminosities,_________ radii,and _________ escape velocities.

Accepted Answer

A)  large;large;large
B)  large;small;large
C)  large;large;small
D)  small;large;small
E)  small;small;largeF) C) and E)
G) C) and D)

Question 5

As a low-mass main-sequence star runs out of fuel in its core,it grows more luminous.How is this possible?

Accepted Answer

A)  It explodes.
B)  It begins to fuse helium in the core.
C)  The core expands as it runs out of fuel.
D)  The core shrinks,bringing more hydrogen fuel into the burning region.
E)  Convection takes place throughout the interior,bringing more fuel to the core.F) C) and D)
G) None of the above D

Question 6

What is the escape velocity from the surface of a 1 M⨀ AGB star that has a radius of 100 R⨀?

Accepted Answer

A)  60 km/s
B)  120 km/s
C)  240 km/s
D)  620 km/s
E)  800 km/sF) D) and E)
G) C) and D)

Question 7

A star like the Sun will eventually become an electron degenerate white dwarf star.

Accepted Answer

A) True 
 B)False

Question 8

Stars evolve primarily because they use up the fuel in their cores.

Accepted Answer

A) True 
 B)False

Question 9

When a low-mass star becomes an AGB star and has a temperature of 3300 K,at what wavelength will it shine the brightest?

Accepted Answer

A)  650 nm,red visible
B)  880 nm,infrared
C)  2.5 μm,infrared
D)  1 mm,microwave
E)  10 m,radioF) B) and D)
G) None of the above

Question 10

Consider a red giant star with a luminosity of 200 L⨀ and a radius of 50 R⨀.Using the luminosity-temperature-radius relationship (L ∝ R2T4),calculate how hot this star's surface temperature will be compared to the Sun,whose temperature is 5,800 K.

Accepted Answer

L ∝ R²T⁴
(L/L_⨀) = (R/R...

Question 11

When the Sun becomes an AGB star,its radius will be approximately 100 R⨀.If its mass at this point will be approximately the same as it is now,how will its surface gravity as an AGB star compare to its present surface gravity as a main-sequence star? Note that g GM/R2.

Accepted Answer

Surface gravity: g GM/R².g_MS / g_AGB ...

Question 12

What is "degenerate" in the degenerate core of a white dwarf?

Accepted Answer

Only the electrons a...

Question 13

Place the following evolutionary stages in order from youngest to oldest.

Accepted Answer

A)  1,2,3
B)  2,3,1
C)  3,2,1
D)  3,1,2
E)  2,1,3F) C) and E)
G) C) and D)

Question 14

A star like the Sun will lose about _________ of its mass before it evolves to become a white dwarf.

Accepted Answer

A)  3 percent
B)  30 percent
C)  60 percent
D)  75 percent
E)  90 percentF) A) and E)
G) A) and D)

Question 15

Which star spends the longest time as a main-sequence star?

Accepted Answer

A)  0.5 M⨀
B)  1 M⨀
C)  3 M⨀
D)  6 M⨀
E)  10 M⨀F) C) and D)
G) B) and C)

Question 16

As a red giant star evolves,hydrogen shell burning proceeds increasingly faster due to:

Accepted Answer

A)  rotational energy from the star's rapid rotation
B)  heat released from the core's contraction
C)  pressure from the contracting envelope
D)  release of energy stored in magnetic fields
E)  energy from the fusion of heavier elementsF) A) and E)
G) None of the above

Question 17

A particular asymptotic giant branch star has approximately the same mass as the Sun but 100 times its radius.Compared to the Sun,what is the escape velocity from that star?

Accepted Answer

A)  0.01 times that of the Sun
B)  0.1 times that of the Sun
C)  the same as that of the Sun
D)  10 times that of the Sun
E)  100 times that of the SunF) A) and C)
G) A) and B)

Question 18

The luminosity of a star depends on:

Accepted Answer

A)  its mass and age
B)  its mass
C)  its age
D)  its distance
E)  its mass,age,and distanceF) None of the above
G) B) and E)

Question 19

The percentage of hydrogen in the Sun's core today is roughly half of what it was originally.

Accepted Answer

A) True 
 B)False  True

Question 20

A 10M⨀ star will evolve through the same phases as a 1M⨀ star.

Accepted Answer

A) True 
 B)False

Exam 16: Evolution of Low-Mass Stars

Consider a 1 M_⨀ star's journey up the red giant branch.Its luminosity will change from 10 L_⨀ to nearly 1,000 L_⨀.How will its temperature and radius change as the star ascends? (Recall that L ∝ R²T⁴. )

If an 0.8 M_⨀ white dwarf could accrete matter from a binary companion at a rate of 10⁻⁹ M_⨀/yr,how long would it take before it exploded as a Type I supernova?

Correct Answer
verified

Using this diagram,identify the star with the smallest radius.

Correct Answer
verified

Asymptotic giant-branch stars have _____ luminosities,_ radii,and _____ escape velocities.

Correct Answer
verified

As a low-mass main-sequence star runs out of fuel in its core,it grows more luminous.How is this possible?

Correct Answer
verified
D

What is the escape velocity from the surface of a 1 M_⨀ AGB star that has a radius of 100 R_⨀?

Correct Answer
verified

A star like the Sun will eventually become an electron degenerate white dwarf star.

Correct Answer
verified

Stars evolve primarily because they use up the fuel in their cores.

Correct Answer
verified

When a low-mass star becomes an AGB star and has a temperature of 3300 K,at what wavelength will it shine the brightest?

Correct Answer
verified

Consider a red giant star with a luminosity of 200 L_⨀ and a radius of 50 R_⨀.Using the luminosity-temperature-radius relationship (L ∝ R²T⁴),calculate how hot this star's surface temperature will be compared to the Sun,whose temperature is 5,800 K.

Correct Answer
verified
L ∝ R²T⁴
(L/L_⨀) = (R/R...
View Answer

When the Sun becomes an AGB star,its radius will be approximately 100 R_⨀.If its mass at this point will be approximately the same as it is now,how will its surface gravity as an AGB star compare to its present surface gravity as a main-sequence star? Note that g GM/R².

Correct Answer
verified
Surface gravity: g GM/R².g_MS / g_AGB ...
View Answer

What is "degenerate" in the degenerate core of a white dwarf?

Correct Answer
verified
Only the electrons a...
View Answer

Place the following evolutionary stages in order from youngest to oldest.

Correct Answer
verified

A star like the Sun will lose about _________ of its mass before it evolves to become a white dwarf.

Correct Answer
verified

Which star spends the longest time as a main-sequence star?

Correct Answer
verified

As a red giant star evolves,hydrogen shell burning proceeds increasingly faster due to:

Correct Answer
verified

A particular asymptotic giant branch star has approximately the same mass as the Sun but 100 times its radius.Compared to the Sun,what is the escape velocity from that star?

Correct Answer
verified

The luminosity of a star depends on:

Correct Answer
verified

The percentage of hydrogen in the Sun's core today is roughly half of what it was originally.

Correct Answer
verified
True

A 10M_⨀ star will evolve through the same phases as a 1M_⨀ star.

Correct Answer
verified

Exam 16: Evolution of Low-Mass Stars

Consider a 1 M⨀ star's journey up the red giant branch.Its luminosity will change from 10 L⨀ to nearly 1,000 L⨀.How will its temperature and radius change as the star ascends? (Recall that L ∝ R2T4. )

If an 0.8 M⨀ white dwarf could accrete matter from a binary companion at a rate of 10−9 M⨀/yr,how long would it take before it exploded as a Type I supernova?

Correct AnswerverifiedShow Answer

Using this diagram,identify the star with the smallest radius.

Correct AnswerverifiedShow Answer

Asymptotic giant-branch stars have _________ luminosities,_________ radii,and _________ escape velocities.

Correct AnswerverifiedShow Answer

As a low-mass main-sequence star runs out of fuel in its core,it grows more luminous.How is this possible?

Correct AnswerverifiedD

What is the escape velocity from the surface of a 1 M⨀ AGB star that has a radius of 100 R⨀?

Correct AnswerverifiedShow Answer

A star like the Sun will eventually become an electron degenerate white dwarf star.

Correct AnswerverifiedShow Answer

Stars evolve primarily because they use up the fuel in their cores.

Correct AnswerverifiedShow Answer

When a low-mass star becomes an AGB star and has a temperature of 3300 K,at what wavelength will it shine the brightest?

Correct AnswerverifiedShow Answer

Consider a red giant star with a luminosity of 200 L⨀ and a radius of 50 R⨀.Using the luminosity-temperature-radius relationship (L ∝ R2T4),calculate how hot this star's surface temperature will be compared to the Sun,whose temperature is 5,800 K.

Correct AnswerverifiedL ∝ R2T4 (L/L⨀) = (R/R...View AnswerShow Answer

When the Sun becomes an AGB star,its radius will be approximately 100 R⨀.If its mass at this point will be approximately the same as it is now,how will its surface gravity as an AGB star compare to its present surface gravity as a main-sequence star? Note that g GM/R2.

Correct AnswerverifiedSurface gravity: g GM/R2.gMS / gAGB ...View AnswerShow Answer

What is "degenerate" in the degenerate core of a white dwarf?

Correct AnswerverifiedOnly the electrons a...View AnswerShow Answer

Place the following evolutionary stages in order from youngest to oldest.

Correct AnswerverifiedShow Answer

A star like the Sun will lose about _________ of its mass before it evolves to become a white dwarf.

Correct AnswerverifiedShow Answer

Which star spends the longest time as a main-sequence star?

Correct AnswerverifiedShow Answer

As a red giant star evolves,hydrogen shell burning proceeds increasingly faster due to:

Correct AnswerverifiedShow Answer

A particular asymptotic giant branch star has approximately the same mass as the Sun but 100 times its radius.Compared to the Sun,what is the escape velocity from that star?

Correct AnswerverifiedShow Answer

The luminosity of a star depends on:

Correct AnswerverifiedShow Answer

The percentage of hydrogen in the Sun's core today is roughly half of what it was originally.

Correct AnswerverifiedTrue

A 10M⨀ star will evolve through the same phases as a 1M⨀ star.

Correct AnswerverifiedShow Answer

Consider a 1 M_⨀ star's journey up the red giant branch.Its luminosity will change from 10 L_⨀ to nearly 1,000 L_⨀.How will its temperature and radius change as the star ascends? (Recall that L ∝ R²T⁴. )

If an 0.8 M_⨀ white dwarf could accrete matter from a binary companion at a rate of 10⁻⁹ M_⨀/yr,how long would it take before it exploded as a Type I supernova?

Correct Answer
verified

Correct Answer
verified

Asymptotic giant-branch stars have _____ luminosities,_ radii,and _____ escape velocities.

Correct Answer
verified

Correct Answer
verified
D

What is the escape velocity from the surface of a 1 M_⨀ AGB star that has a radius of 100 R_⨀?

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Consider a red giant star with a luminosity of 200 L_⨀ and a radius of 50 R_⨀.Using the luminosity-temperature-radius relationship (L ∝ R²T⁴),calculate how hot this star's surface temperature will be compared to the Sun,whose temperature is 5,800 K.

Correct Answer
verified
L ∝ R²T⁴
(L/L_⨀) = (R/R...
View Answer

When the Sun becomes an AGB star,its radius will be approximately 100 R_⨀.If its mass at this point will be approximately the same as it is now,how will its surface gravity as an AGB star compare to its present surface gravity as a main-sequence star? Note that g GM/R².

Correct Answer
verified
Surface gravity: g GM/R².g_MS / g_AGB ...
View Answer

Correct Answer
verified
Only the electrons a...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
True

A 10M_⨀ star will evolve through the same phases as a 1M_⨀ star.

Correct Answer
verified