Question 1

Brown dwarfs most commonly form in the nebular disk around another object, much like aplanet.

Accepted Answer

A) True 
 B)False

Question 2

The birth of stars is a battle between gravity and radiation pressure.

Accepted Answer

A) True 
 B)False

Question 3

What is the force that keeps a main sequence star from collapsing on itself?

Accepted Answer

A) magnetism 
B) gravitation 
C) the strong force 
D) radiation pressure 
E) electron degeneration pressure 
A) magnetism 
B) gravitation 
C) the strong force 
D) radiation pressure 
E) electron degeneration pressure

Question 4

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 5

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 6

Stars form from a collapsing cloud that fragments into smaller and smaller pieces. Thisprocess takes about:

Accepted Answer

A) 10,000 years. 
B) 25,000 years. 
C) 100,000 years. 
D) a few million years. 
E) 100 million years. 
A) 10,000 years. 
B) 25,000 years. 
C) 100,000 years. 
D) a few million years. 
E) 100 million years.

Question 7

Stars evolve to the upper left along the main sequence, after forming in the middle.

Accepted Answer

A) True 
 B)False

Question 8

Contrast the brightest stars of young open and old globular clusters.

Accepted Answer

Hot blue main sequence stars light up yo

Question 9

Rotation and magnetism both play key roles in protostar formation.

Accepted Answer

A) True 
 B)False

Question 10

The single most important determinant of the temperature, density, radius, luminosity, andpace of evolution of a protostar is its:

Accepted Answer

A) chemical composition. 
B) magnetic field. 
C) spin. 
D) mass. 
E) molecular composition. 
A) chemical composition. 
B) magnetic field. 
C) spin. 
D) mass. 
E) molecular composition.

Question 11

Besides mass, the other factor that influences where a star appears on the main sequence is:

Accepted Answer

A) distance from Earth. 
B) number of stars in the cluster. 
C) chemical composition of the cloud. 
D) the motion of the star. 
E) the type of cluster the star is formed in. 
A) distance from Earth. 
B) number of stars in the cluster. 
C) chemical composition of the cloud. 
D) the motion of the star. 
E) the type of cluster the star is formed in.

Question 12

All globular clusters in our Milky Way are about how old?

Accepted Answer

A) less than a million years 
B) ten to fifty million years old 
C) one to three billion years old 
D) around ten billion years old 
E) a variety of ages, from newly born to twenty billions years old 
A) less than a million years 
B) ten to fifty million years old 
C) one to three billion years old 
D) around ten billion years old 
E) a variety of ages, from newly born to twenty billions years old

Question 13

A typical protostar may be several thousand times more luminous than our Sun. Where doesthis energy come from?

Accepted Answer

From the release of

Question 14

Which of these is NOT a source of the shock waves that lead to protostars?

Accepted Answer

A) radiation from the OB stars in emission nebulae 
B) expanding Herbig-Haro objects 
C) expanding planetary nebula shells 
D) violent supernovae explosions 
E) collisions between galaxies 
A) radiation from the OB stars in emission nebulae 
B) expanding Herbig-Haro objects 
C) expanding planetary nebula shells 
D) violent supernovae explosions 
E) collisions between galaxies

Question 15

At what stage of evolution do T Tauri stars occur?

Accepted Answer

A) just as the collapsing cloud becomes luminous 
B) when a protostar is on the verge of becoming a main sequence star 
C) just prior to the protostar stage 
D) just after the planetary nebula is expelled 
E) after the star has established itself as a main sequence star 
A) just as the collapsing cloud becomes luminous 
B) when a protostar is on the verge of becoming a main sequence star 
C) just prior to the protostar stage 
D) just after the planetary nebula is expelled 
E) after the star has established itself as a main sequence star

Question 16

Which is characteristic of globular star clusters?

Accepted Answer

A) old age and hundreds of thousands of stars, only about 30 ly wide 
B) no remaining MS stars, but millions of white dwarfs 
C) only brown dwarfs in a yellow ball 100 ly across 
D) bright blue main sequence stars, and thousands of them 
E) a mix of old and young stars, about 100,000 ly across 
A) old age and hundreds of thousands of stars, only about 30 ly wide 
B) no remaining MS stars, but millions of white dwarfs 
C) only brown dwarfs in a yellow ball 100 ly across 
D) bright blue main sequence stars, and thousands of them 
E) a mix of old and young stars, about 100,000 ly across

Question 17

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

Accepted Answer

They are too cool to ignite nuclear fusi

Question 18

Explain how rotation and magnetic fields influence the formation of the protostar.

Accepted Answer

Rotation flattens the dusty co

Question 19

As a star forms, the photosphere first appears:

Accepted Answer

A) when the planetary nebula is expelled. 
B) when the protostar forms. 
C) when contraction slows down. 
D) when nuclear fires ignite. 
E) when the star reaches the main sequence. 
A) when the planetary nebula is expelled. 
B) when the protostar forms. 
C) when contraction slows down. 
D) when nuclear fires ignite. 
E) when the star reaches the main sequence.

Question 20

A typical protostar may be several thousand times more luminous than the Sun. What is thesource of this energy?

Accepted Answer

A) chemical combustion of hydrocarbons 
B) nuclear fusion in its core 
C) from the release of gravitational energy as the protostar continues to shrink 
D) the ionization of the gas as it heats up 
E) from nearby hot stars or supernovae that have initiated the star formation process 
A) chemical combustion of hydrocarbons 
B) nuclear fusion in its core 
C) from the release of gravitational energy as the protostar continues to shrink 
D) the ionization of the gas as it heats up 
E) from nearby hot stars or supernovae that have initiated the star formation process

Exam 19: Star Formation: a Traumatic Birth

Brown dwarfs most commonly form in the nebular disk around another object, much like aplanet.

The birth of stars is a battle between gravity and radiation pressure.

What is the force that keeps a main sequence star from collapsing on itself?

Higher mass protostars enter the main sequence:

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

Stars form from a collapsing cloud that fragments into smaller and smaller pieces. Thisprocess takes about:

Stars evolve to the upper left along the main sequence, after forming in the middle.

Contrast the brightest stars of young open and old globular clusters.

Rotation and magnetism both play key roles in protostar formation.

The single most important determinant of the temperature, density, radius, luminosity, andpace of evolution of a protostar is its:

Besides mass, the other factor that influences where a star appears on the main sequence is:

All globular clusters in our Milky Way are about how old?

A typical protostar may be several thousand times more luminous than our Sun. Where doesthis energy come from?

Which of these is NOT a source of the shock waves that lead to protostars?

At what stage of evolution do T Tauri stars occur?

Which is characteristic of globular star clusters?

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

Explain how rotation and magnetic fields influence the formation of the protostar.

As a star forms, the photosphere first appears:

A typical protostar may be several thousand times more luminous than the Sun. What is thesource of this energy?

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: Earths 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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