Question 1

That brighter Sirius A weighs 3 solar masses,but the white dwarf Sirius B is only about one solar mass implies:

Accepted Answer

A)  that white dwarfs evolve slower than main sequence stars. 
B)  that the collapsed companion transferred mass to Sirius A. 
C)  that there should be a planetary nebula around the Sirius system. 
D)  that Sirius A will be stable three times longer than Sirius B. 
E)  the Sirius A will end up as a black hole, not a white dwarf like its companion. 
A)  that white dwarfs evolve slower than main sequence stars. 
B)  that the collapsed companion transferred mass to Sirius A. 
C)  that there should be a planetary nebula around the Sirius system. 
D)  that Sirius A will be stable three times longer than Sirius B. 
E)  the Sirius A will end up as a black hole, not a white dwarf like its companion. B

Question 2

In globular clusters,the brightest stars will be:

Accepted Answer

A)  massive blue main sequence stars. 
B)  red supergiants. 
C)  T Tauri stars. 
D)  blue stragglers. 
E)  planetary nebulae. 
A)  massive blue main sequence stars. 
B)  red supergiants. 
C)  T Tauri stars. 
D)  blue stragglers. 
E)  planetary nebulae. B

Question 3

Describe the helium flash and why it occurs.

Accepted Answer

When the core of a red giant has reached a temperature of 100 million K,helium fusion can occur.With helium fusion the temperature rises but the pressure does not because it is the electron degenerate pressure which is holding up the core and it is independent of the temperature.Increased pressure would expand the core and cool it but this does not happen.The increase in temperature makes the fusion occur faster,which raises the temperature more and produces a runaway explosion of fusion known as the helium flash.

Question 4

Why can we say a star spends its life trying to maintain equilibrium?

Accepted Answer

A star is only stable when the

Question 5

-Refer to the figure above.What is the name of the path between the points labeled 11 and 12?

Accepted Answer

A)  planetary nebula 
B)  red giant branch 
C)  horizontal branch 
D)  asymptotic giant branch 
E)  white dwarf 
A)  planetary nebula 
B)  red giant branch 
C)  horizontal branch 
D)  asymptotic giant branch 
E)  white dwarf

Question 6

The age of a star cluster can be determined by the luminosity of the main sequence turnoff into the giant stage.

Accepted Answer

A) True 
 B)False

Question 7

Relate hydrostatic equilibrium to the star's mass,composition,and evolution off the main sequence.

Accepted Answer

Hydrostatic equilibrium means that the i

Question 8

How have Hubble images revised our view of the structure of planetary nebulae,and even the potential for the Sun to become one?

Accepted Answer

Instead of just spherical shells,we know

Question 9

When a low-mass star runs out of hydrogen in its core,it gets brighter.Why?

Accepted Answer

Without radiation pressure to

Question 10

Which stars in globular clusters are believed to be examples of mergers?

Accepted Answer

A)  eclipsing binaries 
B)  blue supergiants 
C)  blue stragglers 
D)  brown dwarfs 
E)  planetary nebulae cores 
A)  eclipsing binaries 
B)  blue supergiants 
C)  blue stragglers 
D)  brown dwarfs 
E)  planetary nebulae cores

Question 11

Which of the following best describes the evolutionary track followed on the H-R diagram for the most massive stars?

Accepted Answer

A)  vertically upward, along the left edge of the diagram 
B)  diagonally to lower right, then vertical, then horizontally left 
C)  horizontally right, diagonally to lower left, then horizontally right 
D)  horizontally right 
E)  horizontally right, then forms a clockwise loop 
A)  vertically upward, along the left edge of the diagram 
B)  diagonally to lower right, then vertical, then horizontally left 
C)  horizontally right, diagonally to lower left, then horizontally right 
D)  horizontally right 
E)  horizontally right, then forms a clockwise loop

Question 12

The most famous case of a more massive hot star orbiting with a more evolved but presently less massive red giant is the eclipsing binary:

Accepted Answer

A)  Aldeberan. 
B)  Antares. 
C)  Algol. 
D)  Alberio. 
E)  Altair. 
A)  Aldeberan. 
B)  Antares. 
C)  Algol. 
D)  Alberio. 
E)  Altair.

Question 13

The "helium flash" occurs at what stage in stellar evolution?

Accepted Answer

A)  when the T Tauri bipolar jets shoot out 
B)  in the middle of the main sequence stage 
C)  red giant 
D)  horizontal branch 
E)  planetary nebula 
A)  when the T Tauri bipolar jets shoot out 
B)  in the middle of the main sequence stage 
C)  red giant 
D)  horizontal branch 
E)  planetary nebula

Question 14

Give evidence that magnetism plays a role in planetary nebula formation.

Accepted Answer

Most of them are bipolar ejections,and m

Question 15

Describe what the internal structure of the Sun looks like,indicating what physical phenomena are occurring there.In what respects (internal structure,energy generation,etc.)does the internal structure of a high mass Main Sequence star differ from that of the Sun?

Accepted Answer

Nuclear fusion via the proton-proton cyc

Question 16

Compared to our Sun,a typical white dwarf has:

Accepted Answer

A)  about the same mass and density. 
B)  about the same mass and a million times higher density. 
C)  a larger mass and a 100 times lower density. 
D)  a smaller mass and half the density. 
E)  a smaller mass and twice the density. 
A)  about the same mass and density. 
B)  about the same mass and a million times higher density. 
C)  a larger mass and a 100 times lower density. 
D)  a smaller mass and half the density. 
E)  a smaller mass and twice the density.

Question 17

When a star's inward gravity and outward pressure are balanced,the star is said to be:

Accepted Answer

A)  in gravitational collapse. 
B)  in thermal expansion. 
C)  in rotational equilibrium. 
D)  in hydrostatic equilibrium. 
E)  a stage 2 protostar. 
A)  in gravitational collapse. 
B)  in thermal expansion. 
C)  in rotational equilibrium. 
D)  in hydrostatic equilibrium. 
E)  a stage 2 protostar.

Question 18

-Refer to the figure above.What is the name of the path between the points labeled 13 and 14?

Accepted Answer

A)  planetary nebula 
B)  red giant branch 
C)  horizontal branch 
D)  asymptotic giant branch 
E)  white dwarf 
A)  planetary nebula 
B)  red giant branch 
C)  horizontal branch 
D)  asymptotic giant branch 
E)  white dwarf

Question 19

What is a helium flash?

Accepted Answer

A helium flash is a runaway condition ca

Question 20

The Main Sequence is the first stellar stage in which energy produced by ________ balances the energy lost by radiation from the surface of the star.

Accepted Answer

fusion (of hydrogen

Exam 20: Stellar Evolution: The Life and Death of a Star

That brighter Sirius A weighs 3 solar masses,but the white dwarf Sirius B is only about one solar mass implies:

In globular clusters,the brightest stars will be:

Describe the helium flash and why it occurs.

Why can we say a star spends its life trying to maintain equilibrium?

-Refer to the figure above.What is the name of the path between the points labeled 11 and 12?

The age of a star cluster can be determined by the luminosity of the main sequence turnoff into the giant stage.

Relate hydrostatic equilibrium to the star's mass,composition,and evolution off the main sequence.

How have Hubble images revised our view of the structure of planetary nebulae,and even the potential for the Sun to become one?

When a low-mass star runs out of hydrogen in its core,it gets brighter.Why?

Which stars in globular clusters are believed to be examples of mergers?

Which of the following best describes the evolutionary track followed on the H-R diagram for the most massive stars?

The most famous case of a more massive hot star orbiting with a more evolved but presently less massive red giant is the eclipsing binary:

The "helium flash" occurs at what stage in stellar evolution?

Give evidence that magnetism plays a role in planetary nebula formation.

Describe what the internal structure of the Sun looks like,indicating what physical phenomena are occurring there.In what respects (internal structure,energy generation,etc.)does the internal structure of a high mass Main Sequence star differ from that of the Sun?

Compared to our Sun,a typical white dwarf has:

When a star's inward gravity and outward pressure are balanced,the star is said to be:

-Refer to the figure above.What is the name of the path between the points labeled 13 and 14?

What is a helium flash?

The Main Sequence is the first stellar stage in which energy produced by ________ balances the energy lost by radiation from the surface of the star.

Charting the Heavens: The Foundations of Astronomy

The Copernican Revolution: The Birth of Modern Science

Radiation: Information from the Cosmos

Spectroscopy: The Inner Workings of Atoms

Telescopes: The Tools of Astronomy

The Solar System: Comparative Planetology and Formation Models

Earth: Our Home in Space

The Moon and Mercury: Scorched and Battered Worlds

Venus: Earth's Sister Planet

Mars: A Near Miss for Life?

Jupiter: Giant of the Solar System

Saturn: Spectacular Rings and Mysterious Moons

Uranus and Neptune: The Outer Worlds of the Solar System

Solar System Debris: Keys to Our Origin

Exoplanets: Planetary Systems Beyond Our Own

The Sun: Our Parent Star

The Stars: Giants,Dwarfs,and the Main Sequence

The Interstellar Medium: Gas and Dust among the Stars

Star Formation: A Traumatic Birth

Stellar Explosions: Novae,Supernovae,and the Formation of the Elements

Neutron Stars and Black Holes: Strange States of Matter

The Milky Way Galaxy: A Spiral in Space

Galaxies: Building Blocks of the Universe

Galaxies and Dark Matter: The Large-Scale Structure of the Cosmos

Cosmology: The Big Bang and the Fate of the Universe

The Early Universe: Toward the Beginning of Time

Life in the Universe: Are We Alone?

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