Question 1

What are the stars in the lower part of the instability strip called?

Accepted Answer

A)  T Tauri stars 
B)  protostars 
C)  Cepheid variables 
D)  RR Lyrae variables 
A)  T Tauri stars 
B)  protostars 
C)  Cepheid variables 
D)  RR Lyrae variables

Question 2

Which of these statements about the capability of an O-type star to trigger the formation of other stars is NOT correct?

Accepted Answer

A)  O-type stars are massive. When they form stellar nebulae, as the Sun did, small stars form instead of planets. 
B)  The H II region surrounding an O-type star expands into the giant molecular cloud, producing a shock wave that can compress the un-ionized material and cause it to collapse. 
C)  O-type stars are massive and thus have short lifetimes. After an O-type star erupts in a supernova, the material it ejects into space can eventually condense to form a new generation of stars. 
D)  The shock wave produced when an O-type star forms a supernova can compress the interstellar medium and cause it to collapse. 
A)  O-type stars are massive. When they form stellar nebulae, as the Sun did, small stars form instead of planets. 
B)  The H II region surrounding an O-type star expands into the giant molecular cloud, producing a shock wave that can compress the un-ionized material and cause it to collapse. 
C)  O-type stars are massive and thus have short lifetimes. After an O-type star erupts in a supernova, the material it ejects into space can eventually condense to form a new generation of stars. 
D)  The shock wave produced when an O-type star forms a supernova can compress the interstellar medium and cause it to collapse.

Question 3

The total time the Sun will spend as a main-sequence star is

Accepted Answer

A)  at least 200 billion years (2 *1011) years. 
B)  about 1 million years. 
C)  about 4.5 million years. 
D)  about 10 billion years (1010 years). 
A)  at least 200 billion years (2 *1011) years. 
B)  about 1 million years. 
C)  about 4.5 million years. 
D)  about 10 billion years (1010 years).

Question 4

What is the lowest mass an object can have and still be a star?

Accepted Answer

A)  0.002 solar mass (twice Jupiter's mass) 
B)  0.80 solar mass 
C)  0.08 solar mass 
D)  0.02 solar mass 
A)  0.002 solar mass (twice Jupiter's mass) 
B)  0.80 solar mass 
C)  0.08 solar mass 
D)  0.02 solar mass

Question 5

What is the dominant nuclear reaction during helium burning in the core of a star?

Accepted Answer

A)  (1H + 4He combine to form C.) 
B)  (4He fuses to form C.) 
C)  (2He fuses to form C.) 
D)  (3He fuses to form C.) 
A)  (1H + 4He combine to form C.) 
B)  (4He fuses to form C.) 
C)  (2He fuses to form C.) 
D)  (3He fuses to form C.)

Question 6

How much time does it take for a 1-solar-mass protostar to reach the main sequence?

Accepted Answer

A)  less than 10,000 years 
B)  100,000 to 1 million years 
C)  1-10 billion years 
D)  10-100 million years 
A)  less than 10,000 years 
B)  100,000 to 1 million years 
C)  1-10 billion years 
D)  10-100 million years

Question 7

Will the Sun undergo a helium flash?

Accepted Answer

A)  Yes. 
B)  No. Only stars more massive than the Sun experience a helium flash. 
C)  No. Only stars less massive than the Sun experience a helium flash. 
D)  No. The Sun is now in the correct mass range to experience a helium flash, but by the time it ends its life on the main sequence it will have lost enough mass that it will no longer be in the correct range. 
A)  Yes. 
B)  No. Only stars more massive than the Sun experience a helium flash. 
C)  No. Only stars less massive than the Sun experience a helium flash. 
D)  No. The Sun is now in the correct mass range to experience a helium flash, but by the time it ends its life on the main sequence it will have lost enough mass that it will no longer be in the correct range.

Question 8

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 novae 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 novae per year occurring within the cluster.

Question 9

Compared with the composition of the early Sun, the composition of the gas at the core of a star that has just become a red giant is

Accepted Answer

A)  very different, since thermonuclear fusion has transformed all the hydrogen and helium into heavier elements. 
B)  very different; there is lots of hydrogen but almost no helium left after thermonuclear fusion. 
C)  very different, since thermonuclear fusion has transformed all the hydrogen into helium. 
D)  the same, with a higher fraction of hydrogen than helium since these stars were produced with the same initial material. 
A)  very different, since thermonuclear fusion has transformed all the hydrogen and helium into heavier elements. 
B)  very different; there is lots of hydrogen but almost no helium left after thermonuclear fusion. 
C)  very different, since thermonuclear fusion has transformed all the hydrogen into helium. 
D)  the same, with a higher fraction of hydrogen than helium since these stars were produced with the same initial material.

Question 10

If one were to look for a star at the end of its pre-main-sequence stage, one might observe in which wavelength region?

Accepted Answer

A)  ultraviolet 
B)  visible 
C)  infrared 
D)  radio 
A)  ultraviolet 
B)  visible 
C)  infrared 
D)  radio

Question 11

Protostars are

Accepted Answer

A)  very young objects still contracting before becoming true stars. 
B)  old stars contracting after using up all of their available hydrogen fuel. 
C)  objects with less than about 0.08 solar mass that do not have enough mass to become true stars. 
D)  stars made almost entirely out of protons. 
A)  very young objects still contracting before becoming true stars. 
B)  old stars contracting after using up all of their available hydrogen fuel. 
C)  objects with less than about 0.08 solar mass that do not have enough mass to become true stars. 
D)  stars made almost entirely out of protons.

Question 12

Interstellar extinction is the

Accepted Answer

A)  assimilation of interstellar matter by stars after gravitational attraction and capture. 
B)  reduction of the apparent brightness of stars by scattering and absorption of their light by intervening interstellar clouds. 
C)  wipeout of species on Earth by intense radiation from a nearby supernova. 
D)  deaths of high-mass stars in the space between other long-lived stars. 
A)  assimilation of interstellar matter by stars after gravitational attraction and capture. 
B)  reduction of the apparent brightness of stars by scattering and absorption of their light by intervening interstellar clouds. 
C)  wipeout of species on Earth by intense radiation from a nearby supernova. 
D)  deaths of high-mass stars in the space between other long-lived stars.

Question 13

The bright stars at the center of an emission nebula (H II region) are

Accepted Answer

A)  young O stars and B stars. 
B)  red supergiants. 
C)  hot white dwarfs. 
D)  T Tauri stars. 
A)  young O stars and B stars. 
B)  red supergiants. 
C)  hot white dwarfs. 
D)  T Tauri stars.

Question 14

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 15

It is now believed that MOST stars are

Accepted Answer

A)  isolated and not in binary systems. 
B)  in binary systems. 
C)  more massive than the Sun. 
D)  red giants. 
A)  isolated and not in binary systems. 
B)  in binary systems. 
C)  more massive than the Sun. 
D)  red giants.

Question 16

It is now believed that MOST stars are

Accepted Answer

A)  members of binary systems. 
B)  members of triple systems. 
C)  solitary stars. 
D)  variable stars. 
A)  members of binary systems. 
B)  members of triple systems. 
C)  solitary stars. 
D)  variable stars.

Question 17

There are several mechanisms that can trigger star formation in a cold, dark nebula. In each mechanism, the key to star formation is

Accepted Answer

A)  bathing the cold, dark nebula in ultraviolet radiation and sweeping away some of the colder material. 
B)  compressing the gas and dust so that gravitation will overcome the gas pressure. 
C)  heating the gas so that gas pressure will overcome gravitation. 
D)  subjecting the dark nebula to an intense magnetic field so that supersonic jets will form. 
A)  bathing the cold, dark nebula in ultraviolet radiation and sweeping away some of the colder material. 
B)  compressing the gas and dust so that gravitation will overcome the gas pressure. 
C)  heating the gas so that gas pressure will overcome gravitation. 
D)  subjecting the dark nebula to an intense magnetic field so that supersonic jets will form.

Question 18

When looking for molecular hydrogen, astronomers actually look for

Accepted Answer

A)  atomic hydrogen. 
B)  carbon monoxide. 
C)  carbon dioxide. 
D)  polycyclic aromatic hydrocarbons (PAHs). 
A)  atomic hydrogen. 
B)  carbon monoxide. 
C)  carbon dioxide. 
D)  polycyclic aromatic hydrocarbons (PAHs).

Question 19

What is a Cepheid variable star?

Accepted Answer

A)  one of several classes of stars that pulsate randomly in brightness 
B)  low-mass, horizontal-branch star that pulsates regularly in brightness 
C)  star that normally remains constant in brightness but occasionally flares up in brightness by several magnitudes 
D)  high-mass star that pulsates regularly in brightness 
A)  one of several classes of stars that pulsate randomly in brightness 
B)  low-mass, horizontal-branch star that pulsates regularly in brightness 
C)  star that normally remains constant in brightness but occasionally flares up in brightness by several magnitudes 
D)  high-mass star that pulsates regularly in brightness

Question 20

The lowest mass a protostar can have and still become a star (i.e., start thermonuclear reactions of normal hydrogen in its core) is

Accepted Answer

A)  slightly less than 1/10 of a solar mass. 
B)  slightly less than 1/100 of a solar mass. 
C)  8/10 of a solar mass. 
D)  about 1/2 a solar mass. 
A)  slightly less than 1/10 of a solar mass. 
B)  slightly less than 1/100 of a solar mass. 
C)  8/10 of a solar mass. 
D)  about 1/2 a solar mass.

What are the stars in the lower part of the instability strip called?

Which of these statements about the capability of an O-type star to trigger the formation of other stars is NOT correct?

The total time the Sun will spend as a main-sequence star is

What is the lowest mass an object can have and still be a star?

What is the dominant nuclear reaction during helium burning in the core of a star?

How much time does it take for a 1-solar-mass protostar to reach the main sequence?

Will the Sun undergo a helium flash?

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

Compared with the composition of the early Sun, the composition of the gas at the core of a star that has just become a red giant is

If one were to look for a star at the end of its pre-main-sequence stage, one might observe in which wavelength region?

Protostars are

Interstellar extinction is the

The bright stars at the center of an emission nebula (H II region) are

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

It is now believed that MOST stars are

It is now believed that MOST stars are

There are several mechanisms that can trigger star formation in a cold, dark nebula. In each mechanism, the key to star formation is

When looking for molecular hydrogen, astronomers actually look for

What is a Cepheid variable star?

The lowest mass a protostar can have and still become a star (i.e., start thermonuclear reactions of normal hydrogen in its core) is

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Atomic Physics and Spectra

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

Characterizing Stars

The Death of Stars

Black Holes: Matters of Gravity

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Cosmology

Astrobiology

Filters

Exam 13: The Lives of Stars From Birth Through Middle Age

What are the stars in the lower part of the instability strip called?

Which of these statements about the capability of an O-type star to trigger the formation of other stars is NOT correct?

The total time the Sun will spend as a main-sequence star is

What is the lowest mass an object can have and still be a star?

What is the dominant nuclear reaction during helium burning in the core of a star?

How much time does it take for a 1-solar-mass protostar to reach the main sequence?

Will the Sun undergo a helium flash?

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

Compared with the composition of the early Sun, the composition of the gas at the core of a star that has just become a red giant is

If one were to look for a star at the end of its pre-main-sequence stage, one might observe in which wavelength region?

Protostars are

Interstellar extinction is the

The bright stars at the center of an emission nebula (H II region) are

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

It is now believed that MOST stars are

It is now believed that MOST stars are

There are several mechanisms that can trigger star formation in a cold, dark nebula. In each mechanism, the key to star formation is

When looking for molecular hydrogen, astronomers actually look for

What is a Cepheid variable star?

The lowest mass a protostar can have and still become a star (i.e., start thermonuclear reactions of normal hydrogen in its core) is

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Atomic Physics and Spectra

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

Characterizing Stars

The Death of Stars

Black Holes: Matters of Gravity

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Cosmology

Astrobiology

Filters