Question 1

Which of the following is responsible for heating the bulk of the bubbles of very hot intercloud gas?

Accepted Answer

A)  high-energy radiation from stars 
B)  supernovae 
C)  young O and B stars 
D)  planetary nebulae 
E)  The heating is an even mix of all of these sources. 
A)  high-energy radiation from stars 
B)  supernovae 
C)  young O and B stars 
D)  planetary nebulae 
E)  The heating is an even mix of all of these sources.

Question 2

Explain how each of the following types of ISM are detected by astronomers: hot intercloud gas, H II regions, neutral hydrogen gas, and molecular clouds.

Accepted Answer

Hot intercloud gas is detected by X-rays

Question 3

When a molecular cloud fragments,

Accepted Answer

A)  the least massive stars are the first to form, while the most massive stars take longer. 
B)  the most massive star are the first to form, while the least massive stars take longer. 
C)  the most massive stars promptly explode as supernovae, removing all remaining gas. 
D)  the stars form at the same rate, regardless of their mass. 
E)  interstellar dust is generated, but not stars. 
A)  the least massive stars are the first to form, while the most massive stars take longer. 
B)  the most massive star are the first to form, while the least massive stars take longer. 
C)  the most massive stars promptly explode as supernovae, removing all remaining gas. 
D)  the stars form at the same rate, regardless of their mass. 
E)  interstellar dust is generated, but not stars.

Question 4

The Hayashi track of a low-mass protostar in the H-R diagram is a path of approximately constant

Accepted Answer

A)  density. 
B)  luminosity. 
C)  age. 
D)  temperature. 
E)  radius. 
A)  density. 
B)  luminosity. 
C)  age. 
D)  temperature. 
E)  radius.

Question 5

Use the figure shown below to complete the following statement: A high-mass protostar remains roughly constant in ________ and increases in ________ as it follows its evolutionary track.

Accepted Answer

A)  temperature; luminosity 
B)  radius; temperature 
C)  luminosity; radius 
D)  luminosity; temperature 
E)  radius; luminosity 
A)  temperature; luminosity 
B)  radius; temperature 
C)  luminosity; radius 
D)  luminosity; temperature 
E)  radius; luminosity

Question 6

Why does the surface temperature of a low-mass protostar remain nearly constant as its core contracts?

Accepted Answer

It remains nearly constant bec

Question 7

Where have astronomers observed the existence of planets?

Accepted Answer

A)  in our Solar System 
B)  orbiting stars other than the Sun 
C)  orbiting stars in binary systems 
D)  traveling on their own through the Milky Way, not orbiting a star 
E)  all of these 
A)  in our Solar System 
B)  orbiting stars other than the Sun 
C)  orbiting stars in binary systems 
D)  traveling on their own through the Milky Way, not orbiting a star 
E)  all of these

Question 8

Astronomers cannot observe the entire process of star formation during a human lifetime.What property of star clusters allows them to circumvent much of this problem?

Accepted Answer

Stars in clusters all formed at around t

Question 9

Which of the following stars spend the LEAST amount of time on their Hayashi tracks?

Accepted Answer

A)  type M main-sequence stars 
B)  type B main-sequence stars 
C)  Sun-like (type G) stars 
D)  low-mass red giants 
E)  type F main-sequence stars 
A)  type M main-sequence stars 
B)  type B main-sequence stars 
C)  Sun-like (type G) stars 
D)  low-mass red giants 
E)  type F main-sequence stars

Question 10

If you wanted to study regions where star formation is currently happening, you could look for

Accepted Answer

A)  bright X-ray sources. 
B)  type M stars. 
C)  red giant stars. 
D)  type G main-sequence stars. 
E)  O and B stars. 
A)  bright X-ray sources. 
B)  type M stars. 
C)  red giant stars. 
D)  type G main-sequence stars. 
E)  O and B stars.

Question 11

Why is it possible for self-gravity to dominate over pressure in molecular clouds but not in most interstellar clouds?

Accepted Answer

Molecular clouds are denser (m

Question 12

A typical molecular cloud has a temperature of approximately

Accepted Answer

A)  0.3 K. 
B)  10 K. 
C)  80 K. 
D)  300 K. 
E)  1000 K. 
A)  0.3 K. 
B)  10 K. 
C)  80 K. 
D)  300 K. 
E)  1000 K.

Question 13

Why can we see dust in the interstellar medium better at far-infrared wavelengths than we can at optical wavelengths?

Accepted Answer

Because the dust is cold at temperatures

Question 14

In the interstellar medium, molecules survive in regions with

Accepted Answer

A)  very high temperatures. 
B)  type O and B stars. 
C)  lots of dust. 
D)  frequent supernovas. 
E)  a disk around a protostar. 
A)  very high temperatures. 
B)  type O and B stars. 
C)  lots of dust. 
D)  frequent supernovas. 
E)  a disk around a protostar.

Question 15

What is the most likely explanation for the dark area in the figure shown below?

Accepted Answer

A)  It is a region where there are no stars. 
B)  It is a region with lots of dark matter. 
C)  It is a supermassive black hole. 
D)  It is a region with thick dust blocking the starlight coming from behind it. 
E)  It is a dark star cluster. 
A)  It is a region where there are no stars. 
B)  It is a region with lots of dark matter. 
C)  It is a supermassive black hole. 
D)  It is a region with thick dust blocking the starlight coming from behind it. 
E)  It is a dark star cluster.

Question 16

Use the figure shown below to complete the following statement: As a protostar contracts,

Accepted Answer

A)  the luminosity decreases. 
B)  the luminosity increases. 
C)  the temperature increases. 
D)  the temperature decreases. 
E)  either the luminosity decreases or the temperature increases. 
A)  the luminosity decreases. 
B)  the luminosity increases. 
C)  the temperature increases. 
D)  the temperature decreases. 
E)  either the luminosity decreases or the temperature increases.

Question 17

Describe the general process of how the interstellar medium can create a star.

Accepted Answer

Deep inside of a cold,molecular cloud,gr

Question 18

The figure below shows three pictures of the disk of the Milky Way, taken in three different wavelength ranges.Put the three pictures in order from shortest to longest wavelength.

Accepted Answer

A)  I, II, III 
B)  II, III, I 
C)  I, III, II 
D)  II, I, III 
E)  III, I, II 
A)  I, II, III 
B)  II, III, I 
C)  I, III, II 
D)  II, I, III 
E)  III, I, II

Question 19

Of the following processes at work in molecular clouds, which is the one that will be responsible for the clouds' eventual collapse?

Accepted Answer

A)  magnetic fields 
B)  conservation of angular momentum 
C)  pressure 
D)  gravity 
E)  turbulence 
A)  magnetic fields 
B)  conservation of angular momentum 
C)  pressure 
D)  gravity 
E)  turbulence

Question 20

The entire process of star formation is an evolving balance between ________ and gravity.

Accepted Answer

A)  rotation 
B)  surface temperature 
C)  pressure 
D)  radiation 
E)  distance 
A)  rotation 
B)  surface temperature 
C)  pressure 
D)  radiation 
E)  distance

Exam 15: The Interstellar Medium and Star Formation

Which of the following is responsible for heating the bulk of the bubbles of very hot intercloud gas?

Explain how each of the following types of ISM are detected by astronomers: hot intercloud gas, H II regions, neutral hydrogen gas, and molecular clouds.

When a molecular cloud fragments,

The Hayashi track of a low-mass protostar in the H-R diagram is a path of approximately constant

Use the figure shown below to complete the following statement: A high-mass protostar remains roughly constant in ________ and increases in ________ as it follows its evolutionary track.

Why does the surface temperature of a low-mass protostar remain nearly constant as its core contracts?

Where have astronomers observed the existence of planets?

Astronomers cannot observe the entire process of star formation during a human lifetime.What property of star clusters allows them to circumvent much of this problem?

Which of the following stars spend the LEAST amount of time on their Hayashi tracks?

If you wanted to study regions where star formation is currently happening, you could look for

Why is it possible for self-gravity to dominate over pressure in molecular clouds but not in most interstellar clouds?

A typical molecular cloud has a temperature of approximately

Why can we see dust in the interstellar medium better at far-infrared wavelengths than we can at optical wavelengths?

In the interstellar medium, molecules survive in regions with

What is the most likely explanation for the dark area in the figure shown below?

Use the figure shown below to complete the following statement: As a protostar contracts,

Describe the general process of how the interstellar medium can create a star.

The figure below shows three pictures of the disk of the Milky Way, taken in three different wavelength ranges.Put the three pictures in order from shortest to longest wavelength.

Of the following processes at work in molecular clouds, which is the one that will be responsible for the clouds' eventual collapse?

The entire process of star formation is an evolving balance between ________ and gravity.

Thinking Like an Astronomer

Patterns in the Skymotions of Earth and the Moon

Motion of Astronomical Bodies

Gravity and Orbits

Light

The Tools of the Astronomer

The Formation of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquidthe Giant Planets

Planetary Moons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

Galaxies

The Milky Waya Normal Spiral Galaxy

The Expanding Universe

Cosmology

Large-Scale Structure in the Universe

Life

Filters

Use the figure shown below to complete the following statement: A high-mass protostar remains roughly constant in and increases in as it follows its evolutionary track.