Question 1

Under which of the following circumstances will a protostar lack an accretion disk?

Accepted Answer

A)  The protostar has a jet. 
B)  The protostar's molecular cloud had no heavy elements. 
C)  The protostar's molecular cloud was not spinning. 
D)  The protostar has no binary companion. 
A)  The protostar has a jet. 
B)  The protostar's molecular cloud had no heavy elements. 
C)  The protostar's molecular cloud was not spinning. 
D)  The protostar has no binary companion.

Question 2

Over what timescale do stars in a typical open cluster form,relative to each other?

Accepted Answer

A)  thousands of years 
B)  millions of years 
C)  billions of years 
D)  They form nearly instantaneously. 
A)  thousands of years 
B)  millions of years 
C)  billions of years 
D)  They form nearly instantaneously.

Question 3

Astronomers discover a large number of Herbig-Haro objects arranged along two perpendicular lines centered on an obscured area of the sky,as shown in the figure below.That area most likely contains a:

Accepted Answer

A)  supermassive black hole. 
B)  pair of supermassive black holes. 
C)  protostar. 
D)  pair of protostars. 
A)  supermassive black hole. 
B)  pair of supermassive black holes. 
C)  protostar. 
D)  pair of protostars.

Question 4

Two molecular clouds have identical densities,but cloud A has a radius four times larger than cloud B.How much longer will it take cloud A to collapse than cloud B?

Accepted Answer

A)  They collapse on the same timescale. 
B)  twice as long 
C)  4 times as long 
D)  16 times as long 
A)  They collapse on the same timescale. 
B)  twice as long 
C)  4 times as long 
D)  16 times as long

Question 5

What kind of equilibrium characterizes the relation between gas clouds in the interstellar medium?

Accepted Answer

Pressure e

Question 6

Which of the following effects would be most likely to increase the lifetime of a giant molecular cloud?

Accepted Answer

A)  accelerating the formation of high-mass stars 
B)  accelerating the formation of low-mass stars 
C)  suppressing of the formation of high-mass stars 
D)  suppressing the formation of low-mass stars 
A)  accelerating the formation of high-mass stars 
B)  accelerating the formation of low-mass stars 
C)  suppressing of the formation of high-mass stars 
D)  suppressing the formation of low-mass stars

Question 7

Which of the following is likely to occur in a cluster with high-mass star formation?

Accepted Answer

A)  elephant trunks 
B)  a decrease in the frequency of planets 
C)  triggered star formation 
D)  all of the above 
A)  elephant trunks 
B)  a decrease in the frequency of planets 
C)  triggered star formation 
D)  all of the above

Question 8

What physical principle is responsible for accretion disks forming around protostars?

Accepted Answer

A)  hydrostatic equilibrium 
B)  conservation of angular momentum 
C)  blackbody radiation 
D)  Wien's law 
A)  hydrostatic equilibrium 
B)  conservation of angular momentum 
C)  blackbody radiation 
D)  Wien's law

Question 9

Which part of the interstellar medium is primarily photoionized?

Accepted Answer

A)  molecular clouds 
B)  H I clouds 
C)  warm interstellar medium 
D)  coronal gas 
A)  molecular clouds 
B)  H I clouds 
C)  warm interstellar medium 
D)  coronal gas

Question 10

What kind of interstellar feature is shown by the "X" in the figure below?

Accepted Answer

A reflecti

Question 11

What is the net result of the CNO cycle?

Accepted Answer

A)  One carbon nucleus and four hydrogen nuclei are transformed into one oxygen nucleus, two neutrinos, and energy. 
B)  One carbon nucleus and one helium nucleus are transformed into one oxygen nucleus, two neutrinos, and energy. 
C)  Three helium nuclei are transformed into one carbon nucleus and energy. 
D)  Four hydrogen nuclei are transformed into one helium nucleus, two neutrinos, and energy. 
A)  One carbon nucleus and four hydrogen nuclei are transformed into one oxygen nucleus, two neutrinos, and energy. 
B)  One carbon nucleus and one helium nucleus are transformed into one oxygen nucleus, two neutrinos, and energy. 
C)  Three helium nuclei are transformed into one carbon nucleus and energy. 
D)  Four hydrogen nuclei are transformed into one helium nucleus, two neutrinos, and energy.

Question 12

Why is there some variation in the birth times of stars in open clusters?

Accepted Answer

Turbulence and feedb

Question 13

Which of the following phases of the interstellar medium is coldest?

Accepted Answer

A)  H I clouds 
B)  molecular clouds 
C)  H II regions 
D)  coronal gas 
A)  H I clouds 
B)  molecular clouds 
C)  H II regions 
D)  coronal gas

Question 14

Protostars are surrounded by accretion disks and envelopes.How is the gas in each of these components moving?

Accepted Answer

Envelope gas is free-falling t

Question 15

An interstellar gas cloud has a temperature of 100 K and a density of 50 particles per cubic centimeter.How could an astronomer most easily observe this cloud?

Accepted Answer

A)  atomic hydrogen absorption lines 
B)  molecular absorption lines 
C)  atomic hydrogen emission lines 
D)  molecular emission lines 
A)  atomic hydrogen absorption lines 
B)  molecular absorption lines 
C)  atomic hydrogen emission lines 
D)  molecular emission lines

Question 16

An open cluster is a:

Accepted Answer

A)  globular cluster in the Milky Way's halo. 
B)  gravitationally bound system of thousands of galaxies. 
C)  group of young stars that will later disperse. 
D)  group of molecular clouds. 
A)  globular cluster in the Milky Way's halo. 
B)  gravitationally bound system of thousands of galaxies. 
C)  group of young stars that will later disperse. 
D)  group of molecular clouds.

Question 17

The tracks with arrows shown on the figure below illustrate what evolutionary phase of the stellar life cycle?

Accepted Answer

A)  main sequence 
B)  protostar 
C)  red giant 
D)  horizontal branch 
A)  main sequence 
B)  protostar 
C)  red giant 
D)  horizontal branch

Question 18

How can astronomers observe coronal gas in the interstellar medium?

Accepted Answer

The answer of How can astronomers observe coronal gas in...

Question 19

How do dust particles affect the formation of interstellar molecules?

Accepted Answer

A)  Dust particles collide and break into smaller molecules. 
B)  Dust particles are the building blocks of molecules. 
C)  Dust particles trap other atoms, which can form molecules. 
D)  Radiation from dust particles catalyzes dust formation. 
A)  Dust particles collide and break into smaller molecules. 
B)  Dust particles are the building blocks of molecules. 
C)  Dust particles trap other atoms, which can form molecules. 
D)  Radiation from dust particles catalyzes dust formation.

Question 20

An object with a mass 10 times larger than Jupiter's forms on its own from gravitational collapse in a molecular cloud.What kind of object is it?

Accepted Answer

A)  T Tauri object 
B)  M dwarf 
C)  brown dwarf 
D)  planet 
A)  T Tauri object 
B)  M dwarf 
C)  brown dwarf 
D)  planet

Under which of the following circumstances will a protostar lack an accretion disk?

Over what timescale do stars in a typical open cluster form,relative to each other?

Astronomers discover a large number of Herbig-Haro objects arranged along two perpendicular lines centered on an obscured area of the sky,as shown in the figure below.That area most likely contains a:

Two molecular clouds have identical densities,but cloud A has a radius four times larger than cloud B.How much longer will it take cloud A to collapse than cloud B?

What kind of equilibrium characterizes the relation between gas clouds in the interstellar medium?

Which of the following effects would be most likely to increase the lifetime of a giant molecular cloud?

Which of the following is likely to occur in a cluster with high-mass star formation?

What physical principle is responsible for accretion disks forming around protostars?

Which part of the interstellar medium is primarily photoionized?

What kind of interstellar feature is shown by the "X" in the figure below?

What is the net result of the CNO cycle?

Why is there some variation in the birth times of stars in open clusters?

Which of the following phases of the interstellar medium is coldest?

Protostars are surrounded by accretion disks and envelopes.How is the gas in each of these components moving?

An interstellar gas cloud has a temperature of 100 K and a density of 50 particles per cubic centimeter.How could an astronomer most easily observe this cloud?

An open cluster is a:

The tracks with arrows shown on the figure below illustrate what evolutionary phase of the stellar life cycle?

How can astronomers observe coronal gas in the interstellar medium?

How do dust particles affect the formation of interstellar molecules?

An object with a mass 10 times larger than Jupiter's forms on its own from gravitational collapse in a molecular cloud.What kind of object is it?

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A Universe Made, a Universe Discovered

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A Universe of Universal Laws

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Home Base: Earth and Moon

Sibling Worlds: Mercury, Venus, and Mars

Gas, ice, and Stone: the Outer Planets

Life and the Search for Habitable Worlds

The Sun As a Star

Measuring the Stars: the Main Sequence and Its Meaning

To the Graveyard of Stars: the End Points of Stellar Evolution

Down the Rabbit Hole: Relativity and Black Holes

Our City of Stars: the Milky Way

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Exam 12: Nursery of the Stars: the Interstellar Medium and Star Formation

Under which of the following circumstances will a protostar lack an accretion disk?

Over what timescale do stars in a typical open cluster form,relative to each other?

Astronomers discover a large number of Herbig-Haro objects arranged along two perpendicular lines centered on an obscured area of the sky,as shown in the figure below.That area most likely contains a:

Two molecular clouds have identical densities,but cloud A has a radius four times larger than cloud B.How much longer will it take cloud A to collapse than cloud B?

What kind of equilibrium characterizes the relation between gas clouds in the interstellar medium?

Which of the following effects would be most likely to increase the lifetime of a giant molecular cloud?

Which of the following is likely to occur in a cluster with high-mass star formation?

What physical principle is responsible for accretion disks forming around protostars?

Which part of the interstellar medium is primarily photoionized?

What kind of interstellar feature is shown by the "X" in the figure below?

What is the net result of the CNO cycle?

Why is there some variation in the birth times of stars in open clusters?

Which of the following phases of the interstellar medium is coldest?

Protostars are surrounded by accretion disks and envelopes.How is the gas in each of these components moving?

An interstellar gas cloud has a temperature of 100 K and a density of 50 particles per cubic centimeter.How could an astronomer most easily observe this cloud?

An open cluster is a:

The tracks with arrows shown on the figure below illustrate what evolutionary phase of the stellar life cycle?

How can astronomers observe coronal gas in the interstellar medium?

How do dust particles affect the formation of interstellar molecules?

An object with a mass 10 times larger than Jupiter's forms on its own from gravitational collapse in a molecular cloud.What kind of object is it?

Getting Started: Science, astronomy, and Being Human

A Universe Made, a Universe Discovered

A Universe of Universal Laws

A Universe of Universal Laws

The Architecture and Birth of Planetary Systems

Home Base: Earth and Moon

Sibling Worlds: Mercury, Venus, and Mars

Gas, ice, and Stone: the Outer Planets

Life and the Search for Habitable Worlds

The Sun As a Star

Measuring the Stars: the Main Sequence and Its Meaning

To the Graveyard of Stars: the End Points of Stellar Evolution

Down the Rabbit Hole: Relativity and Black Holes

Our City of Stars: the Milky Way

A Universe of Galaxies

The Cosmic Web: the Large-Scale Structure of the Universe

Cosmology

Filters