Question 1

A large gas cloud in the interstellar medium that contains several type O and B stars would appear to us as:

Accepted Answer

A)  a dark nebula. 
B)  an emission nebula. 
C)  bright blue. 
D)  a reflection nebula. 
E)  a dark patch against a bright background. 
A)  a dark nebula. 
B)  an emission nebula. 
C)  bright blue. 
D)  a reflection nebula. 
E)  a dark patch against a bright background.

Question 2

Neutral hydrogen may be detected between the stars because it emits ________.

Accepted Answer

The answer of Neutral hydrogen may be detected between the...

Question 3

How does emission of long wavelength radio radiation from neutral hydrogen help us overcome the shortcomings of visible light in mapping out distant parts of our galaxy?

Accepted Answer

It allows us to detect interst

Question 4

If the spectra reveal stars A and B are identical,but star A looks bluer in color,then star B's light has been ________ by interstellar dust.

Accepted Answer

The answer of If the spectra reveal stars A and...

Question 5

Astronomers use roman numerals to indicate the ionization state of a gas.Ionized hydrogen is indicated by which of the following symbols?

Accepted Answer

A)  H II 
B)  H₂ 
C)  H I 
D)    
E)  H III 
A)  H II 
B)  H₂ 
C)  H I 
D)    
E)  H III

Question 6

Which is the least dense?

Accepted Answer

A)  interstellar gas 
B)  interstellar dust 
C)  the atmosphere of Earth 
D)  the atmosphere of Jupiter 
E)  the atmosphere of the Sun 
A)  interstellar gas 
B)  interstellar dust 
C)  the atmosphere of Earth 
D)  the atmosphere of Jupiter 
E)  the atmosphere of the Sun

Question 7

Interstellar matter is distributed very evenly through the galaxy.

Accepted Answer

A) True 
 B)False

Question 8

Almost all molecules in space are based on what element? Why?

Accepted Answer

Carbon forms a host of chains of complex

Question 9

What are the properties of the neutral hydrogen gas that exists in the interstellar medium?

Accepted Answer

Neutral hydrogen dominates the compositi

Question 10

Why is 21-cm radiation so important to the study of interstellar matter and the Galaxy?

Accepted Answer

A)  It helps locate the galactic core in Sagittarius. 
B)  Emitted by hydrogen, it passes through interstellar dust and lets us to map the entire Galaxy. 
C)  Emitted by carbon monoxide, it passes through interstellar gas and lets us to see places rich in organic molecules around the Galaxy. 
D)  It is emitted by most stars, enabling astronomers to map the entire Galaxy. 
E)  It is emitted only in hot regions of star formation, so the pattern of the spiral arms of the Galaxy can be mapped. 
A)  It helps locate the galactic core in Sagittarius. 
B)  Emitted by hydrogen, it passes through interstellar dust and lets us to map the entire Galaxy. 
C)  Emitted by carbon monoxide, it passes through interstellar gas and lets us to see places rich in organic molecules around the Galaxy. 
D)  It is emitted by most stars, enabling astronomers to map the entire Galaxy. 
E)  It is emitted only in hot regions of star formation, so the pattern of the spiral arms of the Galaxy can be mapped.

Question 11

The dark dust clouds can be explored better with infrared than with visible light.

Accepted Answer

A) True 
 B)False

Question 12

Interstellar absorption lines are narrow primarily because:

Accepted Answer

A)  there is very little interstellar matter. 
B)  molecules always produce narrow absorption lines. 
C)  most of the matter is ionized, and atoms moving fast produce sharp lines. 
D)  the matter is at a low temperature, and atoms are almost still. 
E)  All of the above are correct. 
A)  there is very little interstellar matter. 
B)  molecules always produce narrow absorption lines. 
C)  most of the matter is ionized, and atoms moving fast produce sharp lines. 
D)  the matter is at a low temperature, and atoms are almost still. 
E)  All of the above are correct.

Question 13

Charles Messier mapped the night sky and identified many objects now known to be emission nebulae in his search for objects that might be confused with:

Accepted Answer

A)  comets. 
B)  asteroids. 
C)  galaxies. 
D)  dark nebulae. 
E)  reflection nebulae. 
A)  comets. 
B)  asteroids. 
C)  galaxies. 
D)  dark nebulae. 
E)  reflection nebulae.

Question 14

The Local Bubble was probably created by:

Accepted Answer

A)  the strong solar winds created by the new-born Sun. 
B)  the Crab Nebula supernova of 1054 AD. 
C)  the magnetic fields of the Milky Way in our spiral arm. 
D)  a nearby supernova perhaps 300,000 years ago, brighter than the full Moon. 
E)  the interaction between the solar wind and the Oort Cloud. 
A)  the strong solar winds created by the new-born Sun. 
B)  the Crab Nebula supernova of 1054 AD. 
C)  the magnetic fields of the Milky Way in our spiral arm. 
D)  a nearby supernova perhaps 300,000 years ago, brighter than the full Moon. 
E)  the interaction between the solar wind and the Oort Cloud.

Question 15

Emission nebulae occur only near stars that emit large amounts of ________ electromagnetic radiation.

Accepted Answer

The answer of Emission nebulae occur only near stars that...

Question 16

Why can radio waves get through the dust clouds,but light is blocked?

Accepted Answer

The interstellar dust grains a

Question 17

What are the very cold (about 20 K),dense clouds of gas thought to be the most massive objects in the Galaxy called?

Accepted Answer

A)  emission nebulae 
B)  absorption clouds 
C)  dust clouds 
D)  molecular clouds 
E)  reflection nebulae 
A)  emission nebulae 
B)  absorption clouds 
C)  dust clouds 
D)  molecular clouds 
E)  reflection nebulae

Question 18

Unlike atoms,molecules can:

Accepted Answer

A)  rotate. 
B)  vibrate. 
C)  spin. 
D)  Both A and B. 
E)  All of the above. 
A)  rotate. 
B)  vibrate. 
C)  spin. 
D)  Both A and B. 
E)  All of the above.

Question 19

Some regions along the plane of the Milky Way appear dark because:

Accepted Answer

A)  there are no stars in these areas. 
B)  stars in that region are hidden by interstellar gas. 
C)  stars in that region are hidden by dark dust particles. 
D)  many brown dwarfs in those areas absorb light which they turn into heat. 
E)  many black holes absorb all light from those directions. 
A)  there are no stars in these areas. 
B)  stars in that region are hidden by interstellar gas. 
C)  stars in that region are hidden by dark dust particles. 
D)  many brown dwarfs in those areas absorb light which they turn into heat. 
E)  many black holes absorb all light from those directions.

Question 20

Ionization of hydrogen in H II regions is most visible at:

Accepted Answer

A)  12,367 nm, the Paschen alpha line. 
B)  656.3 nm, Balmer alpha line for 3-2 electron transition. 
C)  21 cm in the radio region for the spin-flip of its electron. 
D)  121.3 nm, the Lyman alpha ultraviolet line for 2-1 electron transition. 
E)  473.2 nm, the blue-green emission line for 4-2 electron transition. 
A)  12,367 nm, the Paschen alpha line. 
B)  656.3 nm, Balmer alpha line for 3-2 electron transition. 
C)  21 cm in the radio region for the spin-flip of its electron. 
D)  121.3 nm, the Lyman alpha ultraviolet line for 2-1 electron transition. 
E)  473.2 nm, the blue-green emission line for 4-2 electron transition.

Exam 18: The Interstellar Medium: Gas and Dust among the Stars

A large gas cloud in the interstellar medium that contains several type O and B stars would appear to us as:

Neutral hydrogen may be detected between the stars because it emits ________.

How does emission of long wavelength radio radiation from neutral hydrogen help us overcome the shortcomings of visible light in mapping out distant parts of our galaxy?

If the spectra reveal stars A and B are identical,but star A looks bluer in color,then star B's light has been ________ by interstellar dust.

Astronomers use roman numerals to indicate the ionization state of a gas.Ionized hydrogen is indicated by which of the following symbols?

Which is the least dense?

Interstellar matter is distributed very evenly through the galaxy.

Almost all molecules in space are based on what element? Why?

What are the properties of the neutral hydrogen gas that exists in the interstellar medium?

Why is 21-cm radiation so important to the study of interstellar matter and the Galaxy?

The dark dust clouds can be explored better with infrared than with visible light.

Interstellar absorption lines are narrow primarily because:

Charles Messier mapped the night sky and identified many objects now known to be emission nebulae in his search for objects that might be confused with:

The Local Bubble was probably created by:

Emission nebulae occur only near stars that emit large amounts of ________ electromagnetic radiation.

Why can radio waves get through the dust clouds,but light is blocked?

What are the very cold (about 20 K),dense clouds of gas thought to be the most massive objects in the Galaxy called?

Unlike atoms,molecules can:

Some regions along the plane of the Milky Way appear dark because:

Ionization of hydrogen in H II regions is most visible at:

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

Star Formation: A Traumatic Birth

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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