Question 1

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

Accepted Answer

A)  0.5 M $\odot$ 
B)  1 M $\odot$ 
C)  3 M $\odot$ 
D)  6 M $\odot$ 
E)  10 M $\odot$ 
A)  0.5 M $\odot$ 
B)  1 M $\odot$ 
C)  3 M $\odot$ 
D)  6 M $\odot$ 
E)  10 M $\odot$ A

Question 2

How many times longer does a 2 M $\odot$  main-sequence star live compared to a 10 M $\odot$  main-sequence star?

Accepted Answer

Main-sequence lifetime: $ \tau $_MS = 10¹⁰ yr * (M/M _$\odot$ ) ^- ^2.5 2M_$\odot$: $ \tau $_MS = 10¹⁰ yr * 2^-^2.5 = 1.8 * 10 ⁹ yr = 1.8 billion yr. 10M_$\odot$: $ \tau $_MS =10¹⁰ yr = 10^-^2.5 = 3.1* 10⁷ yr = 0.031 billion yr. Therefore, the 2M _$\odot$ star lives 1.8/0.031 = 58 times longer than the 10M _$\odot$ star.

Question 3

What are two ways that Type I supernovae can be produced?

Accepted Answer

A)  mass transfer and stellar mergers 
B)  helium flash and stellar mergers 
C)  mass transfer and helium flash 
D)  helium burning and mass transfer 
E)  carbon burning and mass transfer 
A)  mass transfer and stellar mergers 
B)  helium flash and stellar mergers 
C)  mass transfer and helium flash 
D)  helium burning and mass transfer 
E)  carbon burning and mass transfer A

Question 4

Pressure from degenerate electrons keeps the core of a red giant star from collapsing.

Accepted Answer

A) True 
 B)False

Question 5

Explain which types of main-sequence stars would be more likely to have planets with complex life.

Accepted Answer

Low-mass main-sequence stars have longer

Question 6

Asymptotic giant branch stars have high-mass loss rates because:

Accepted Answer

A)  they are rotating quickly 
B)  they have weak magnetic fields 
C)  they have strong magnetic fields 
D)  they have low surface gravity 
E)  they have high surface temperatures 
A)  they are rotating quickly 
B)  they have weak magnetic fields 
C)  they have strong magnetic fields 
D)  they have low surface gravity 
E)  they have high surface temperatures

Question 7

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

Accepted Answer

A) True 
 B)False

Question 8

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

Accepted Answer

Only the electrons a

Question 9

One star in a binary will almost always become a red giant before the other because:

Accepted Answer

A)  one star is always larger in radius than the other 
B)  binaries always have one star twice as massive as the other 
C)  small differences in main-sequence masses yield large differences in main-sequence ages 
D)  the more massive binary star always gets more mass from the less massive binary star when both are main-sequence stars 
E)  one star always spins faster than the other 
A)  one star is always larger in radius than the other 
B)  binaries always have one star twice as massive as the other 
C)  small differences in main-sequence masses yield large differences in main-sequence ages 
D)  the more massive binary star always gets more mass from the less massive binary star when both are main-sequence stars 
E)  one star always spins faster than the other

Question 10

What is the name of the nuclear reaction illustrated here?

Accepted Answer

A)  the proton-proton chain 
B)  the CNO cycle 
C)  beta decay 
D)  the triple-alpha process 
E)  the alpha-beta reaction 
A)  the proton-proton chain 
B)  the CNO cycle 
C)  beta decay 
D)  the triple-alpha process 
E)  the alpha-beta reaction

Question 11

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. 
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.

Question 12

Explain the significance of Roche lobes in a binary system.

Accepted Answer

The Roche lobe is an imaginary line of e

Question 13

What is the shortest phase of evolution for a one solar mass star that we can visibly see?

Accepted Answer

The planetary nebula phase is

Question 14

As a main-sequence star burns its core supply of hydrogen, what happens?

Accepted Answer

A)  Helium begins to fuse throughout the core. 
B)  Helium fuses in a shell surrounding the core. 
C)  Helium fusion takes place only at the very center of the core, where temperature and pressure are highest. 
D)  Helium builds up as ash in the core. 
E)  Helium builds up everywhere in the star's interior. 
A)  Helium begins to fuse throughout the core. 
B)  Helium fuses in a shell surrounding the core. 
C)  Helium fusion takes place only at the very center of the core, where temperature and pressure are highest. 
D)  Helium builds up as ash in the core. 
E)  Helium builds up everywhere in the star's interior.

Question 15

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 Sun 
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 Sun

Question 16

During which phase of the evolution of a low-mass star does it have two separate regions of nuclear burning occurring in its interior?

Accepted Answer

A)  pre-main sequence 
B)  main sequence 
C)  red giant 
D)  horizontal branch 
E)  white dwarf 
A)  pre-main sequence 
B)  main sequence 
C)  red giant 
D)  horizontal branch 
E)  white dwarf

Question 17

The Sun eventually could become a nova.

Accepted Answer

A) True 
 B)False

Question 18

A Type I supernova has a luminosity of approximately:

Accepted Answer

A)  10 thousand L $\odot$ 
B)  10 million L $\odot$ 
C)  1 billion L $\odot$ 
D)  10 billion L $\odot$ 
E)  10 trillion L $\odot$ 
A)  10 thousand L $\odot$ 
B)  10 million L $\odot$ 
C)  1 billion L $\odot$ 
D)  10 billion L $\odot$ 
E)  10 trillion L $\odot$

Question 19

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, 3 
A)  1, 2, 3 
B)  2, 3, 1 
C)  3, 2, 1 
D)  3, 1, 2 
E)  2, 1, 3

Question 20

If an 0.8 M $\odot$  white dwarf could accrete matter from a binary companion at a rate of 10 - 9 M $\odot$ /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 years 
A)  600 thousand years 
B)  20 million years 
C)  200 million years 
D)  600 million years 
E)  1 billion years

Exam 16: Evolution of Low-Mass Stars

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

How many times longer does a 2 M ⊙\odot⊙ main-sequence star live compared to a 10 M ⊙\odot⊙ main-sequence star?

What are two ways that Type I supernovae can be produced?

Pressure from degenerate electrons keeps the core of a red giant star from collapsing.

Explain which types of main-sequence stars would be more likely to have planets with complex life.

Asymptotic giant branch stars have high-mass loss rates because:

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

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

One star in a binary will almost always become a red giant before the other because:

What is the name of the nuclear reaction illustrated here?

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

Explain the significance of Roche lobes in a binary system.

What is the shortest phase of evolution for a one solar mass star that we can visibly see?

As a main-sequence star burns its core supply of hydrogen, what happens?

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?

During which phase of the evolution of a low-mass star does it have two separate regions of nuclear burning occurring in its interior?

The Sun eventually could become a nova.

A Type I supernova has a luminosity of approximately:

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

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

Why Learn Astronomy

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Taking the Measure of Stars

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Evolution of High-Mass Stars

Relativity and Black Holes

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How many times longer does a 2 M _$\odot$ main-sequence star live compared to a 10 M _$\odot$ main-sequence star?

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