Question 1

The main-sequence lifetime of a star is given by which equation?

Accepted Answer

A)  t   M/L 
B)  t   L/M 
C)  t   M 2/L 
D)  t   L2/L 
E)  t   M/L2 
A)  t   M/L 
B)  t   L/M 
C)  t   M 2/L 
D)  t   L2/L 
E)  t   M/L2 A

Question 2

Place the evolutionary stages shown in the figure below in order from earliest to latest.

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 D

Question 3

A star's surface temperature during the horizontal branch phase is determined primarily by its

Accepted Answer

A)  luminosity. 
B)  mass and chemical composition. 
C)  magnetic field strength. 
D)  rotation rate. 
E)  radius. 
A)  luminosity. 
B)  mass and chemical composition. 
C)  magnetic field strength. 
D)  rotation rate. 
E)  radius. B

Question 4

During evolutionary phase A in the figure shown below, the star is ________.In evolutionary phase B, it is ________.

Accepted Answer

A)  expanding; expanding 
B)  expanding; contracting 
C)  contracting; losing mass 
D)  contracting; contracting 
E)  gaining mass; contracting 
A)  expanding; expanding 
B)  expanding; contracting 
C)  contracting; losing mass 
D)  contracting; contracting 
E)  gaining mass; contracting

Question 5

How can the core of a star be degenerate with respect to the electrons but nondegenerate with respect to the nuclei?

Accepted Answer

(1)Quantum mechanics says electrons take

Question 6

When the Sun becomes an AGB star, its radius will be approximately 100 RSUN.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

Question 7

The core of an asymptotic giant branch star is filled with

Accepted Answer

A)  hydrogen gas. 
B)  electron-degenerate hydrogen. 
C)  helium gas. 
D)  electron-degenerate helium. 
E)  electron-degenerate carbon. 
A)  hydrogen gas. 
B)  electron-degenerate hydrogen. 
C)  helium gas. 
D)  electron-degenerate helium. 
E)  electron-degenerate carbon.

Question 8

A feature unique to main-sequence stars is that

Accepted Answer

A)  hydrostatic equilibrium exists at all radii. 
B)  energy transport occurs via convection throughout much of their interiors. 
C)  carbon burning occurs in their cores. 
D)  they emit strong surface winds. 
E)  hydrogen burning occurs in their cores. 
A)  hydrostatic equilibrium exists at all radii. 
B)  energy transport occurs via convection throughout much of their interiors. 
C)  carbon burning occurs in their cores. 
D)  they emit strong surface winds. 
E)  hydrogen burning occurs in their cores.

Question 9

How long will a 2 MSUN star live as a main-sequence star?

Accepted Answer

A)  12 million years 
B)  180 million years 
C)  1.8 billion years 
D)  12 billion years 
E)  18 billion years 
A)  12 million years 
B)  180 million years 
C)  1.8 billion years 
D)  12 billion years 
E)  18 billion years

Question 10

Considering their lifetimes, 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 11

What is a white dwarf star, and what are the major properties of such a star?

Accepted Answer

A white dwarf star is a tiny (Earth-size

Question 12

The low-end mass cutoff for stars occurs at approximately

Accepted Answer

A)  0.08 MSUN. 
B)  0.1 MSUN. 
C)  0.8 MSUN. 
D)  1 MSUN. 
E)  10 MSUN. 
A)  0.08 MSUN. 
B)  0.1 MSUN. 
C)  0.8 MSUN. 
D)  1 MSUN. 
E)  10 MSUN.

Question 13

What types of chemical elements can low-mass stars contribute to the enrichment of the interstellar medium and how are they produced?

Accepted Answer

Low-mass stars can enrich the interstell

Question 14

What is a planetary nebula, and why are many planetary nebulae not symmetrical?

Accepted Answer

A planetary nebula is formed when the ou

Question 15

A 10 MSUN star will evolve through the same phases as a

Accepted Answer

A)  1 MSUN star. 
B)  5 MSUN star. 
C)  20 MSUN star. 
D)  0.5 MSUN star. 
E)  0.08 MSUN star. 
A)  1 MSUN star. 
B)  5 MSUN star. 
C)  20 MSUN star. 
D)  0.5 MSUN star. 
E)  0.08 MSUN star.

Question 16

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 fusing 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 fusing region. 
E)  Convection takes place throughout the interior, bringing more fuel to the core.

Question 17

A 1-MSUN star in a binary system could eventually create which chemical element and eject it into the interstellar medium?

Accepted Answer

A)  carbon 
B)  helium 
C)  iron 
D)  all of these 
E)  none of these 
A)  carbon 
B)  helium 
C)  iron 
D)  all of these 
E)  none of these

Question 18

Describe the similarities and differences between the helium flash in the core of a red giant star and the explosive hydrogen burning on the surface of a white dwarf star.

Accepted Answer

In the red giant core,degenerate electro

Question 19

When matter is packed so tightly together that quantum physics will not allow the electrons to get any closer, it is called

Accepted Answer

A)  electron-degenerate. 
B)  neutron-degenerate 
C)  nucleon-degenerate. 
D)  quantum-limited. 
E)  exotic matter. 
A)  electron-degenerate. 
B)  neutron-degenerate 
C)  nucleon-degenerate. 
D)  quantum-limited. 
E)  exotic matter.

Question 20

When helium fusion begins in the core of a red giant star, the situation quickly gets out of control because electron-degeneracy pressure does not respond to changes in

Accepted Answer

A)  luminosity. 
B)  density. 
C)  gravity. 
D)  temperature. 
E)  magnetic field strength. 
A)  luminosity. 
B)  density. 
C)  gravity. 
D)  temperature. 
E)  magnetic field strength.

Exam 16: Evolution of Low-Mass Stars

The main-sequence lifetime of a star is given by which equation?

Place the evolutionary stages shown in the figure below in order from earliest to latest.

A star's surface temperature during the horizontal branch phase is determined primarily by its

During evolutionary phase A in the figure shown below, the star is ________.In evolutionary phase B, it is ________.

How can the core of a star be degenerate with respect to the electrons but nondegenerate with respect to the nuclei?

When the Sun becomes an AGB star, its radius will be approximately 100 RSUN.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.)

The core of an asymptotic giant branch star is filled with

A feature unique to main-sequence stars is that

How long will a 2 MSUN star live as a main-sequence star?

Considering their lifetimes, which types of main-sequence stars would be more likely to have planets with complex life?

What is a white dwarf star, and what are the major properties of such a star?

The low-end mass cutoff for stars occurs at approximately

What types of chemical elements can low-mass stars contribute to the enrichment of the interstellar medium and how are they produced?

What is a planetary nebula, and why are many planetary nebulae not symmetrical?

A 10 MSUN star will evolve through the same phases as a

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

A 1-MSUN star in a binary system could eventually create which chemical element and eject it into the interstellar medium?

Describe the similarities and differences between the helium flash in the core of a red giant star and the explosive hydrogen burning on the surface of a white dwarf star.

When matter is packed so tightly together that quantum physics will not allow the electrons to get any closer, it is called

When helium fusion begins in the core of a red giant star, the situation quickly gets out of control because electron-degeneracy pressure does not respond to changes in

Thinking Like an Astronomer

Patterns in the Skymotions of Earth and the Moon

Motion of Astronomical Bodies

Gravity and Orbits

Light

The Tools of the Astronomer

The Formation of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquidthe Giant Planets

Planetary Moons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

The Interstellar Medium and Star Formation

Evolution of High-Mass Stars

Relativity and Black Holes

Galaxies

The Milky Waya Normal Spiral Galaxy

The Expanding Universe

Cosmology

Large-Scale Structure in the Universe

Life

Filters

During evolutionary phase A in the figure shown below, the star is .In evolutionary phase B, it is .

When the Sun becomes an AGB star, its radius will be approximately 100 R_SUN.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.)

How long will a 2 M_SUN star live as a main-sequence star?

A 10 M_SUNstar will evolve through the same phases as a

A 1-M_SUN star in a binary system could eventually create which chemical element and eject it into the interstellar medium?