Question 1

Why are brown dwarfs difficult to detect? Why have we had recent successes?

Accepted Answer

They are too cool to ignite nuclear fusi

Question 2

What makes the subject of star formation so difficult and complex?

Accepted Answer

A)  It is so slow that no visible proof of it exists. 
B)  Star formation is too expensive to study in detail. 
C)  Stars live too long to be observed from birth to death. 
D)  Clouds, fragments, protostars, stars, and nebulae all interact and influence each other. 
E)  Shock waves disrupt the orderly evolution of stars. 
A)  It is so slow that no visible proof of it exists. 
B)  Star formation is too expensive to study in detail. 
C)  Stars live too long to be observed from birth to death. 
D)  Clouds, fragments, protostars, stars, and nebulae all interact and influence each other. 
E)  Shock waves disrupt the orderly evolution of stars.

Question 3

Why does a star's luminosity drop so much during the Hayashi track?

Accepted Answer

The surface of the star maintains a fair

Question 4

How long does it take for a star like our Sun to form?

Accepted Answer

A)  100 thousand years 
B)  two million years 
C)  fifty million years 
D)  one billion years 
E)  4.6 billion years 
A)  100 thousand years 
B)  two million years 
C)  fifty million years 
D)  one billion years 
E)  4.6 billion years

Question 5

Our Sun,along with most of the stars in our neighborhood,probably formed:

Accepted Answer

A)  a few million years ago. 
B)  about 10 million years ago. 
C)  hundreds of millions of years ago. 
D)  billions of years ago. 
E)  at the beginning of the universe. 
A)  a few million years ago. 
B)  about 10 million years ago. 
C)  hundreds of millions of years ago. 
D)  billions of years ago. 
E)  at the beginning of the universe.

Question 6

What is the key factor that determines the temperature,density,radius,luminosity,and pace of evolution of a protostellar object?

Accepted Answer

A)  composition of the nebula 
B)  rotation of the nebula 
C)  mass of the nebula 
D)  temperature of the nebula 
E)  magnetism of the nebula 
A)  composition of the nebula 
B)  rotation of the nebula 
C)  mass of the nebula 
D)  temperature of the nebula 
E)  magnetism of the nebula

Question 7

Which relationship concerning the mass of protostars is FALSE?

Accepted Answer

A)  The more massive ones will reach the main sequence first. 
B)  The more massive ones will be the hottest and most luminous. 
C)  The more massive ones one will be made of the heaviest elements. 
D)  The more massive ones are so luminous they ionize the gas, hence red H II regions. 
E)  The more massive ones create a lot of ultraviolet as well as visible light. 
A)  The more massive ones will reach the main sequence first. 
B)  The more massive ones will be the hottest and most luminous. 
C)  The more massive ones one will be made of the heaviest elements. 
D)  The more massive ones are so luminous they ionize the gas, hence red H II regions. 
E)  The more massive ones create a lot of ultraviolet as well as visible light.

Question 8

Higher mass protostars enter the main sequence:

Accepted Answer

A)  faster and at a higher luminosity and temperature. 
B)  faster and at a lower luminosity and temperature. 
C)  slower and at a higher luminosity and temperature. 
D)  slower and at a lower luminosity and temperature. 
E)  at the same rate, but at a higher luminosity and temperature. 
A)  faster and at a higher luminosity and temperature. 
B)  faster and at a lower luminosity and temperature. 
C)  slower and at a higher luminosity and temperature. 
D)  slower and at a lower luminosity and temperature. 
E)  at the same rate, but at a higher luminosity and temperature.

Question 9

Discuss the relationship between young stars and the interstellar medium.

Accepted Answer

Young stars give off ultraviolet radiati

Question 10

Most stars are usually formed singularly or as binaries,not in clusters.

Accepted Answer

A) True 
 B)False

Question 11

What factors can complicate the collapse of an interstellar cloud into a star?

Accepted Answer

The initial spin of the cloud and the co

Question 12

Brown dwarfs are most easily detected which portion of the electromagnetic spectrum?

Accepted Answer

A)  X-ray 
B)  ultraviolet 
C)  visible light 
D)  infrared 
E)  radio 
A)  X-ray 
B)  ultraviolet 
C)  visible light 
D)  infrared 
E)  radio

Question 13

Protostars can be observed in:

Accepted Answer

A)  the Crab Nebula. 
B)  the Andromeda Galaxy. 
C)  the Orion Nebula. 
D)  our Solar System. 
E)  the Helix Nebula. 
A)  the Crab Nebula. 
B)  the Andromeda Galaxy. 
C)  the Orion Nebula. 
D)  our Solar System. 
E)  the Helix Nebula.

Question 14

A protostar of 20 solar masses will probably turn into a type O main sequence star.

Accepted Answer

A) True 
 B)False

Question 15

During a protostar's T Tauri phase,it:

Accepted Answer

A)  begins a period of reduced activity. 
B)  expands dramatically. 
C)  lies on the main sequence. 
D)  may develop very strong winds. 
E)  changes its spin direction. 
A)  begins a period of reduced activity. 
B)  expands dramatically. 
C)  lies on the main sequence. 
D)  may develop very strong winds. 
E)  changes its spin direction.

Question 16

In the collapsing cloud fragment stage (stage 2)of star formation,the size of the cloud fragment is about:

Accepted Answer

A)  the size of the solar system. 
B)  10 times the size of the solar system. 
C)  100 times the size of the solar system. 
D)  1,000 times the size of the solar system. 
E)  10,000 times the size of the solar system. 
A)  the size of the solar system. 
B)  10 times the size of the solar system. 
C)  100 times the size of the solar system. 
D)  1,000 times the size of the solar system. 
E)  10,000 times the size of the solar system.

Question 17

Brown dwarfs are failed stars,never igniting their hydrogen fusion.

Accepted Answer

A) True 
 B)False

Question 18

At the end of the Kelvin-Helmholtz contraction a star is hundreds of times brighter than it will be as a main sequence star.

Accepted Answer

A) True 
 B)False

Question 19

How long does it take an O-type star to form,compared to the time for a solar-type star to form?

Accepted Answer

A)  1/300 as long 
B)  1/30 as long 
C)  about the same time 
D)  30 times longer 
E)  300 times longer 
A)  1/300 as long 
B)  1/30 as long 
C)  about the same time 
D)  30 times longer 
E)  300 times longer

Question 20

Type M stars evolve to the main sequence faster than our G type Sun.

Accepted Answer

A) True 
 B)False

Exam 19: Star Formation: A Traumatic Birth

Why are brown dwarfs difficult to detect? Why have we had recent successes?

What makes the subject of star formation so difficult and complex?

Why does a star's luminosity drop so much during the Hayashi track?

How long does it take for a star like our Sun to form?

Our Sun,along with most of the stars in our neighborhood,probably formed:

What is the key factor that determines the temperature,density,radius,luminosity,and pace of evolution of a protostellar object?

Which relationship concerning the mass of protostars is FALSE?

Higher mass protostars enter the main sequence:

Discuss the relationship between young stars and the interstellar medium.

Most stars are usually formed singularly or as binaries,not in clusters.

What factors can complicate the collapse of an interstellar cloud into a star?

Brown dwarfs are most easily detected which portion of the electromagnetic spectrum?

Protostars can be observed in:

A protostar of 20 solar masses will probably turn into a type O main sequence star.

During a protostar's T Tauri phase,it:

In the collapsing cloud fragment stage (stage 2)of star formation,the size of the cloud fragment is about:

Brown dwarfs are failed stars,never igniting their hydrogen fusion.

At the end of the Kelvin-Helmholtz contraction a star is hundreds of times brighter than it will be as a main sequence star.

How long does it take an O-type star to form,compared to the time for a solar-type star to form?

Type M stars evolve to the main sequence faster than our G type Sun.

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

Stellar Evolution: The Life and Death of a Star

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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