Question 1

An object that is too massive to be a planet but not massive enough to be a star is called a:

Accepted Answer

A)  red dwarf. 
B)  brown dwarf. 
C)  white dwarf. 
D)  T Tauri star. 
A)  red dwarf. 
B)  brown dwarf. 
C)  white dwarf. 
D)  T Tauri star.

Question 2

The end of the life of a red dwarf star is predicted to be a sphere of almost pure helium.But no such spheres have been detected.What do we believe is the reason?

Accepted Answer

A)  These helium stars are very dim and consequently hard to detect. 
B)  There are very few red dwarfs, so their end products are expected to be rare. 
C)  The evolution rate for red dwarfs is so slow that none has yet evolved to its end stage. 
D)  Helium is a relatively light material, so these helium spheres are expected to dissipate in a short time. 
A)  These helium stars are very dim and consequently hard to detect. 
B)  There are very few red dwarfs, so their end products are expected to be rare. 
C)  The evolution rate for red dwarfs is so slow that none has yet evolved to its end stage. 
D)  Helium is a relatively light material, so these helium spheres are expected to dissipate in a short time.

Question 3

The age of a cluster of stars can be judged by the:

Accepted Answer

A)  amount of radioactive elements detected on the surfaces of its stars. 
B)  turnoff point on the main sequence of its Hertzsprung-Russell diagram. 
C)  total number of stars within the cluster. 
D)  number of novas per year occurring within the cluster. 
A)  amount of radioactive elements detected on the surfaces of its stars. 
B)  turnoff point on the main sequence of its Hertzsprung-Russell diagram. 
C)  total number of stars within the cluster. 
D)  number of novas per year occurring within the cluster.

Question 4

Why do many H II regions glow with a prominent red color?

Accepted Answer

A)  Ionized hydrogen, like neutral hydrogen, has the Hα line as one of its electron transitions. 
B)  Ionized hydrogen does not emit a red line, but it has a yellow line and a magenta line, and the combination of these produces the sensation of red. 
C)  We cannot detect ionized hydrogen directly, so we use CO as a tracer. And CO produces a red line. 
D)  The free protons and electrons which make up the plasma of an H II region can reunite briefly to form a hydrogen atom. In the process the red Hα line is emitted. 
A)  Ionized hydrogen, like neutral hydrogen, has the Hα line as one of its electron transitions. 
B)  Ionized hydrogen does not emit a red line, but it has a yellow line and a magenta line, and the combination of these produces the sensation of red. 
C)  We cannot detect ionized hydrogen directly, so we use CO as a tracer. And CO produces a red line. 
D)  The free protons and electrons which make up the plasma of an H II region can reunite briefly to form a hydrogen atom. In the process the red Hα line is emitted.

Question 5

What are the products of helium burning in a star?

Accepted Answer

A)  magnesium and silicon 
B)  nitrogen and oxygen 
C)  carbon and oxygen 
D)  hydrogen and lithium 
A)  magnesium and silicon 
B)  nitrogen and oxygen 
C)  carbon and oxygen 
D)  hydrogen and lithium

Question 6

Why does the Hertzsprung-Russell diagram of a globular cluster NOT contain any stars with high luminosity and high temperature on the main sequence?

Accepted Answer

A)  These high-mass stars evolved away from the main sequence long ago. 
B)  Stars that will occupy this position on the main sequence have not yet evolved there from the protostar stage. 
C)  The stars that were in this position on the main sequence have undergone splitting into binary stars and hence appear lower down on the diagram. 
D)  This type of cluster contains only low-mass stars and has never had high-luminosity stars on its main sequence. 
A)  These high-mass stars evolved away from the main sequence long ago. 
B)  Stars that will occupy this position on the main sequence have not yet evolved there from the protostar stage. 
C)  The stars that were in this position on the main sequence have undergone splitting into binary stars and hence appear lower down on the diagram. 
D)  This type of cluster contains only low-mass stars and has never had high-luminosity stars on its main sequence.

Question 7

How much of the visible mass of the Milky Way Galaxy is in the form of gas and dust spread out between the stars?

Accepted Answer

A)  90% 
B)  less than 1% 
C)  50% 
D)  10% 
A)  90% 
B)  less than 1% 
C)  50% 
D)  10%

Question 8

Which statement about a globular cluster is NOT true?

Accepted Answer

A)  A globular cluster can contain up to 1 million stars. 
B)  A globular cluster contains only low-mass stars on the main sequence. 
C)  A globular cluster does not contain main-sequence stars. 
D)  A globular cluster has a round shape. 
A)  A globular cluster can contain up to 1 million stars. 
B)  A globular cluster contains only low-mass stars on the main sequence. 
C)  A globular cluster does not contain main-sequence stars. 
D)  A globular cluster has a round shape.

Question 9

New stars are formed from:

Accepted Answer

A)  hot supernova remnants. 
B)  activity around black holes in the centers of galaxies. 
C)  huge, cool dust and gas clouds. 
D)  pure energy in free space. 
A)  hot supernova remnants. 
B)  activity around black holes in the centers of galaxies. 
C)  huge, cool dust and gas clouds. 
D)  pure energy in free space.

Question 10

Giant molecular clouds,which are major sites of star formation,can be up to:

Accepted Answer

A)  10 times the size of the solar system and contain 2 to 3 solar masses of material. 
B)  10 pc across and contain a few thousand solar masses of material. 
C)  100 pc across and contain 2 million solar masses of material. 
D)  1000 pc across and contain 100 million solar masses of material. 
A)  10 times the size of the solar system and contain 2 to 3 solar masses of material. 
B)  10 pc across and contain a few thousand solar masses of material. 
C)  100 pc across and contain 2 million solar masses of material. 
D)  1000 pc across and contain 100 million solar masses of material.

Question 11

What is the ultimate fate of an open star cluster?

Accepted Answer

A)  The shape of the cluster will remain more or less as it is at the present time as the stars in it age and die. 
B)  The stars in the cluster escape one by one until the cluster no longer exists. 
C)  Over time, the stars collide and merge, eventually creating a black hole. 
D)  The stars gradually sink toward the center, creating a globular cluster. 
A)  The shape of the cluster will remain more or less as it is at the present time as the stars in it age and die. 
B)  The stars in the cluster escape one by one until the cluster no longer exists. 
C)  Over time, the stars collide and merge, eventually creating a black hole. 
D)  The stars gradually sink toward the center, creating a globular cluster.

Question 12

In which regions of the Milky Way Galaxy are giant molecular clouds of H₂ and CO gas found?

Accepted Answer

A)  uniformly spread throughout the Galaxy, both in and above and below the spiral arms 
B)  the center of the Galaxy 
C)  above and below the plane of the spiral arms, over the galactic poles 
D)  along the spiral arms 
A)  uniformly spread throughout the Galaxy, both in and above and below the spiral arms 
B)  the center of the Galaxy 
C)  above and below the plane of the spiral arms, over the galactic poles 
D)  along the spiral arms

Question 13

How hot does the core of a star have to be for helium burning to begin?

Accepted Answer

A)  100 million K 
B)  1 billion K 
C)  1 million K 
D)  10 million K 
A)  100 million K 
B)  1 billion K 
C)  1 million K 
D)  10 million K

Question 14

The main-sequence lifetime of a star with half the mass of the Sun:

Accepted Answer

A)  could be longer or shorter than that of the Sun; more information is required to determine the length of its lifetime. 
B)  is longer than that of the Sun. 
C)  is the same as that of the Sun because mass does not affect the lifetime of a star. 
D)  is shorter than that of the Sun. 
A)  could be longer or shorter than that of the Sun; more information is required to determine the length of its lifetime. 
B)  is longer than that of the Sun. 
C)  is the same as that of the Sun because mass does not affect the lifetime of a star. 
D)  is shorter than that of the Sun.

Question 15

On the Hertzsprung-Russell diagram,in which direction does the position occupied by a star move after helium burning begins in the star's core?

Accepted Answer

A)  toward the upper right 
B)  toward the lower left 
C)  toward the lower right 
D)  toward the upper left 
A)  toward the upper right 
B)  toward the lower left 
C)  toward the lower right 
D)  toward the upper left

Question 16

When a star leaves the main sequence and expands toward the red giant region,what is happening inside the star?

Accepted Answer

A)  Helium burning is taking place in a spherical shell just outside the core; the core itself is almost pure carbon and oxygen. 
B)  Hydrogen burning is taking place in a spherical shell just outside the core; the core itself is almost pure helium. 
C)  Hydrogen burning is taking place in a spherical shell just outside the core; the core has not yet started thermonuclear reactions and is still mostly hydrogen. 
D)  Helium is being converted into carbon and oxygen in the core. 
A)  Helium burning is taking place in a spherical shell just outside the core; the core itself is almost pure carbon and oxygen. 
B)  Hydrogen burning is taking place in a spherical shell just outside the core; the core itself is almost pure helium. 
C)  Hydrogen burning is taking place in a spherical shell just outside the core; the core has not yet started thermonuclear reactions and is still mostly hydrogen. 
D)  Helium is being converted into carbon and oxygen in the core.

Question 17

In some binary star systems,such as β Lyrae,essentially no light is seen from the more massive star because the:

Accepted Answer

A)  more massive star is hidden by an accretion disk of material from the less massive star. 
B)  orbit of the more massive star keeps it hidden behind the larger but less massive star as seen from Earth. 
C)  more massive star is a black hole from which light cannot escape. 
D)  more massive star is still hidden in the dust clouds from which it formed. 
A)  more massive star is hidden by an accretion disk of material from the less massive star. 
B)  orbit of the more massive star keeps it hidden behind the larger but less massive star as seen from Earth. 
C)  more massive star is a black hole from which light cannot escape. 
D)  more massive star is still hidden in the dust clouds from which it formed.

Question 18

In the H-R diagram shown in Figure 11-28b of Comins,Discovering the Essential Universe,6th ed.,the brightest stars in the Pleiades cluster are not on the main sequence but away from it toward the upper right.Explain.

Accepted Answer

A)  The brightest stars have not yet reached the main sequence and are in the T Tauri phase. 
B)  The brightest stars have already evolved through the red giant phase and have now returned to the blue giant phase on their way to the white dwarf phase. 
C)  The brightest stars have already become white dwarf stars, as shown by their position. 
D)  These blue supergiant stars have already begun to evolve toward the red supergiant phase. 
A)  The brightest stars have not yet reached the main sequence and are in the T Tauri phase. 
B)  The brightest stars have already evolved through the red giant phase and have now returned to the blue giant phase on their way to the white dwarf phase. 
C)  The brightest stars have already become white dwarf stars, as shown by their position. 
D)  These blue supergiant stars have already begun to evolve toward the red supergiant phase.

Question 19

Which statement about open star clusters is TRUE?

Accepted Answer

A)  Open star clusters slowly condense into globular clusters as the stars drive off the remaining interstellar dust and gas. 
B)  One star in an open cluster eventually undergoes a supernova explosion that quickly disperses the other stars. 
C)  As open star clusters slowly condense, their residual rotation spins them into a flat pancake shape and they become spiral galaxies. 
D)  The motions of individual stars are such that all open clusters eventually disperse. 
A)  Open star clusters slowly condense into globular clusters as the stars drive off the remaining interstellar dust and gas. 
B)  One star in an open cluster eventually undergoes a supernova explosion that quickly disperses the other stars. 
C)  As open star clusters slowly condense, their residual rotation spins them into a flat pancake shape and they become spiral galaxies. 
D)  The motions of individual stars are such that all open clusters eventually disperse.

Question 20

What is believed to be the MOST important factor determining whether a collapsing region (dense core)in an interstellar cloud becomes a single-star or a multiple-star system?

Accepted Answer

A)  the fraction of heavy elements in the cloud 
B)  the temperature 
C)  the mass of the collapsing region 
D)  the amount of rotation (spin) 
A)  the fraction of heavy elements in the cloud 
B)  the temperature 
C)  the mass of the collapsing region 
D)  the amount of rotation (spin)

An object that is too massive to be a planet but not massive enough to be a star is called a:

The end of the life of a red dwarf star is predicted to be a sphere of almost pure helium.But no such spheres have been detected.What do we believe is the reason?

The age of a cluster of stars can be judged by the:

Why do many H II regions glow with a prominent red color?

What are the products of helium burning in a star?

Why does the Hertzsprung-Russell diagram of a globular cluster NOT contain any stars with high luminosity and high temperature on the main sequence?

How much of the visible mass of the Milky Way Galaxy is in the form of gas and dust spread out between the stars?

Which statement about a globular cluster is NOT true?

New stars are formed from:

Giant molecular clouds,which are major sites of star formation,can be up to:

What is the ultimate fate of an open star cluster?

In which regions of the Milky Way Galaxy are giant molecular clouds of H₂ and CO gas found?

How hot does the core of a star have to be for helium burning to begin?

The main-sequence lifetime of a star with half the mass of the Sun:

On the Hertzsprung-Russell diagram,in which direction does the position occupied by a star move after helium burning begins in the star's core?

When a star leaves the main sequence and expands toward the red giant region,what is happening inside the star?

In some binary star systems,such as β Lyrae,essentially no light is seen from the more massive star because the:

In the H-R diagram shown in Figure 11-28b of Comins,Discovering the Essential Universe,6th ed.,the brightest stars in the Pleiades cluster are not on the main sequence but away from it toward the upper right.Explain.

Which statement about open star clusters is TRUE?

What is believed to be the MOST important factor determining whether a collapsing region (dense core)in an interstellar cloud becomes a single-star or a multiple-star system?

Discovering the Night Sky

Gravitation and the Waltz of the Planets

Light and Telescopes

Formation of the Solar System and Other Planetary Systems

Exoplanets

The Terrestrial Planets and Their Moons

The Outer Planets and Their Moons

Vagabonds of the Solar System

The Sun: Our Extraordinary Ordinary Star

Characterizing Stars

The Deaths and Remnants of Stars

The Galaxies

Cosmology

Astrobiology

Filters

Exam 11: The Lives of the Stars From Birth Through Middle Age

An object that is too massive to be a planet but not massive enough to be a star is called a:

The end of the life of a red dwarf star is predicted to be a sphere of almost pure helium.But no such spheres have been detected.What do we believe is the reason?

The age of a cluster of stars can be judged by the:

Why do many H II regions glow with a prominent red color?

What are the products of helium burning in a star?

Why does the Hertzsprung-Russell diagram of a globular cluster NOT contain any stars with high luminosity and high temperature on the main sequence?

How much of the visible mass of the Milky Way Galaxy is in the form of gas and dust spread out between the stars?

Which statement about a globular cluster is NOT true?

New stars are formed from:

Giant molecular clouds,which are major sites of star formation,can be up to:

What is the ultimate fate of an open star cluster?

In which regions of the Milky Way Galaxy are giant molecular clouds of H₂ and CO gas found?

How hot does the core of a star have to be for helium burning to begin?

The main-sequence lifetime of a star with half the mass of the Sun:

On the Hertzsprung-Russell diagram,in which direction does the position occupied by a star move after helium burning begins in the star's core?

When a star leaves the main sequence and expands toward the red giant region,what is happening inside the star?

In some binary star systems,such as β Lyrae,essentially no light is seen from the more massive star because the:

In the H-R diagram shown in Figure 11-28b of Comins,Discovering the Essential Universe,6th ed.,the brightest stars in the Pleiades cluster are not on the main sequence but away from it toward the upper right.Explain.

Which statement about open star clusters is TRUE?

What is believed to be the MOST important factor determining whether a collapsing region (dense core)in an interstellar cloud becomes a single-star or a multiple-star system?

Discovering the Night Sky

Gravitation and the Waltz of the Planets

Light and Telescopes

Formation of the Solar System and Other Planetary Systems

Exoplanets

The Terrestrial Planets and Their Moons

The Outer Planets and Their Moons

Vagabonds of the Solar System

The Sun: Our Extraordinary Ordinary Star

Characterizing Stars

The Deaths and Remnants of Stars

The Galaxies

Cosmology

Astrobiology

Filters