Question 1

A fragment of a collapsing gas cloud that comes to equilibrium with a central temperature of 4 million K will become a:

Accepted Answer

A)  black hole. 
B)  brown dwarf. 
C)  black dwarf. 
D)  T Tauri star. 
E)  stage 1 protostar. 
A)  black hole. 
B)  brown dwarf. 
C)  black dwarf. 
D)  T Tauri star. 
E)  stage 1 protostar. B

Question 2

What are the characteristics of an open cluster of stars?

Accepted Answer

A)  mostly found above and below the galactic plane 
B)  old age and millions of members 
C)  a few hundred, mainly main sequence stars 
D)  All stars are much more massive than our Sun. 
E)  All stars are about the same age and luminosity. 
A)  mostly found above and below the galactic plane 
B)  old age and millions of members 
C)  a few hundred, mainly main sequence stars 
D)  All stars are much more massive than our Sun. 
E)  All stars are about the same age and luminosity. C

Question 3

An interstellar gas cloud has the mass to form hundreds of stars.What generally happens to it?

Accepted Answer

The cloud fragments into smaller clouds and forms many stars.

Question 4

The birthplaces of stars correspond to the ________ clouds in the interstellar medium.

Accepted Answer

densest (a

Question 5

What event marks the birth of a new star?

Accepted Answer

The ignition of nucl

Question 6

Rotation and magnetism both play key roles in protostar formation.

Accepted Answer

A) True 
 B)False

Question 7

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 8

How long does it take an M class star to reach the main sequence,compared to a solar type star?

Accepted Answer

A)  a tenth as long 
B)  about the same, 30 million years 
C)  about twice as long 
D)  about twenty times longer 
E)  longer than the age of the Galaxy 
A)  a tenth as long 
B)  about the same, 30 million years 
C)  about twice as long 
D)  about twenty times longer 
E)  longer than the age of the Galaxy

Question 9

In stage 6 or 7 of the formation of a large cluster of stars,a nebula is formed around the cluster.This happens because:

Accepted Answer

A)  the number of stars is so great and so intense that the gas from the original cloud is ionized. 
B)  the stars are out of their cocoons of dust and their radiation ionizes the gas from the original cloud. 
C)  there are brown dwarfs everywhere in between the stars, so the gas is lit up by their low-intensity light. 
D)  there are thousands of Sun-like stars with planets around them and the formation of planets ionizes the leftover gas. 
E)  there are massive O and B stars emitting high energy photons that ionize the remainder of the cloud. 
A)  the number of stars is so great and so intense that the gas from the original cloud is ionized. 
B)  the stars are out of their cocoons of dust and their radiation ionizes the gas from the original cloud. 
C)  there are brown dwarfs everywhere in between the stars, so the gas is lit up by their low-intensity light. 
D)  there are thousands of Sun-like stars with planets around them and the formation of planets ionizes the leftover gas. 
E)  there are massive O and B stars emitting high energy photons that ionize the remainder of the cloud.

Question 10

Which event marks the birth of a star?

Accepted Answer

A)  formation of the planetary nebula 
B)  fusion of hydrogen atoms into helium atoms 
C)  collapse of an interstellar cloud 
D)  formation of a photosphere 
E)  instability in an interstellar cloud 
A)  formation of the planetary nebula 
B)  fusion of hydrogen atoms into helium atoms 
C)  collapse of an interstellar cloud 
D)  formation of a photosphere 
E)  instability in an interstellar cloud

Question 11

What do we mean by the term molecular clouds? Why do they exist? How can observation of their properties yield clues to the processes of stellar formation?

Accepted Answer

Molecular clouds are very cool interstel

Question 12

Atomic bomb tests demonstrated which aspect of star formation?

Accepted Answer

A)  A shock wave surrounding and compressing a molecular cloud. 
B)  The ignition of fusion that changes a protostar to a star. 
C)  A protostar's movement on the Hayashi track. 
D)  The fragmentation of a molecular cloud. 
E)  A shock wave pushing a molecular cloud from one side. 
A)  A shock wave surrounding and compressing a molecular cloud. 
B)  The ignition of fusion that changes a protostar to a star. 
C)  A protostar's movement on the Hayashi track. 
D)  The fragmentation of a molecular cloud. 
E)  A shock wave pushing a molecular cloud from one side.

Question 13

Why are star clusters almost ideal "laboratories" for stellar studies?

Accepted Answer

A)  All stars in the cluster are the same size and luminosity. 
B)  Their combined light makes them much easier to spot from a distance. 
C)  Stars in clusters have the same age, similar composition, and are at the same distance away. 
D)  Stars in clusters are all relatively young and therefore shine brightly. 
E)  Like our Sun, stars in clusters are always located in the plane of the Milky Way Galaxy. 
A)  All stars in the cluster are the same size and luminosity. 
B)  Their combined light makes them much easier to spot from a distance. 
C)  Stars in clusters have the same age, similar composition, and are at the same distance away. 
D)  Stars in clusters are all relatively young and therefore shine brightly. 
E)  Like our Sun, stars in clusters are always located in the plane of the Milky Way Galaxy.

Question 14

A protostar develops a bipolar flow of gas when it is still surrounded by an equatorial disk of ________.

Accepted Answer

The answer of A protostar develops a bipolar flow of...

Question 15

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 16

Outline the process of star formation,including all relevant factors that influence the outcome.

Accepted Answer

An interstellar cloud,disturbed in some

Question 17

Most stars,probably all stars,formed:

Accepted Answer

A)  in a binary system. 
B)  in a triple system. 
C)  in a cluster of stars. 
D)  all by themselves. 
E)  There is no theory to predict this. 
A)  in a binary system. 
B)  in a triple system. 
C)  in a cluster of stars. 
D)  all by themselves. 
E)  There is no theory to predict this.

Question 18

Why does the term "planet" have a different meaning when applied to brown dwarfs than in our solar system?

Accepted Answer

In our solar system,a planet is a large

Question 19

A protostar of 20 solar masses should form a star that will stay on the main sequence twenty times longer than our Sun.

Accepted Answer

A) True 
 B)False

Question 20

What stage of star formation is ZAMS?

Accepted Answer

At stage 7,the zero age main s

Exam 19: Star Formation: A Traumatic Birth

A fragment of a collapsing gas cloud that comes to equilibrium with a central temperature of 4 million K will become a:

What are the characteristics of an open cluster of stars?

An interstellar gas cloud has the mass to form hundreds of stars.What generally happens to it?

The birthplaces of stars correspond to the ________ clouds in the interstellar medium.

What event marks the birth of a new star?

Rotation and magnetism both play key roles in protostar formation.

Which is characteristic of globular star clusters?

How long does it take an M class star to reach the main sequence,compared to a solar type star?

In stage 6 or 7 of the formation of a large cluster of stars,a nebula is formed around the cluster.This happens because:

Which event marks the birth of a star?

What do we mean by the term molecular clouds? Why do they exist? How can observation of their properties yield clues to the processes of stellar formation?

Atomic bomb tests demonstrated which aspect of star formation?

Why are star clusters almost ideal "laboratories" for stellar studies?

A protostar develops a bipolar flow of gas when it is still surrounded by an equatorial disk of ________.

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

Outline the process of star formation,including all relevant factors that influence the outcome.

Most stars,probably all stars,formed:

Why does the term "planet" have a different meaning when applied to brown dwarfs than in our solar system?

A protostar of 20 solar masses should form a star that will stay on the main sequence twenty times longer than our Sun.

What stage of star formation is ZAMS?

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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