Question 1

Which of the following statements comparing halo stars to our Sun is not true?

Accepted Answer

A)   Most stars in the halo have either died or are in their final stages of life, while the Sun is only in about the middle of its lifetime.
B)   Most stars in the halo have cooler surface temperatures than the Sun.
C)   Most stars in the halo are less luminous than the Sun.
D)   Most stars in the halo contain a much lower percentage of heavy elements than the Sun.

Question 2

What produces the 21-cm radio line that we can be used to map the Milky Way Galaxy?

Accepted Answer

A)   atomic hydrogen
B)   ionized hydrogen
C)   molecular hydrogen
D)   carbon monoxide
E)   helium

Question 3

Explain why in space, "no one can hear you scream."

Accepted Answer

Screams, and any sound that we make, are...

Question 4

Most of the mass of the Milky Way is located in the halo of the galaxy in the form of dark matter.

Accepted Answer

A) True 
 B)False

Question 5

Fill in the blank: Elements heavier than hydrogen and helium constitute about ________ of the mass of the interstellar medium.

Accepted Answer

A)   0.002%
B)   2%
C)   70%
D)   98%

Question 6

Suppose you want to observe and study the radiation from gas inside an interstellar bubble created by a supernova. Which of the following observatories will be most useful?

Accepted Answer

A)   The Chandra X-ray Observatory
B)   The Keck I telescope on the summit of Mauna Kea
C)   The SOFIA airborne infrared observatory
D)   The Hubble Space Telescope

Question 7

What happens after many generations of the star-gas-star cycle?

Accepted Answer

A)   The heavy element abundance decreases, the amount of gas increases.
B)   The heavy element abundance increases, the amount of gas increases.
C)   The amount of gas and heavy elements stay the same: it's a cycle.
D)   The heavy element abundance increases, the amount of gas stays the same.
E)   The heavy element abundance stays the same, the amount of gas decreases. F)  The heavy element abundance increases, the amount of gas decreases.

Question 8

What do we call the bright, sphere-shaped region of stars that occupies the central few thousand light-years of the Milky Way Galaxy?

Accepted Answer

A)   the galaxy's disk
B)   the galaxy's bulge
C)   a globular cluster
D)   the galaxy's halo

Question 9

Based on observations, which of the following statements about stars in the Milky Way is generally true?

Accepted Answer

A)   The older the star, the lower its abundance of heavy elements.
B)   The older the star, the bluer its color.
C)   The older the star, the faster its orbital speed.
D)   The younger the star, the higher its mass.
E)   The less massive the star, the older it is.

Question 10

Astronomers observe huge bubbles of hot gas, some over a thousand light years across, in the Milky Way. What is their cause?

Accepted Answer

These huge bubbles, called "superbubbles...

Question 11

How can we see through the interstellar medium?

Accepted Answer

A)   by observing at wavelengths (high-energy X-rays and long wavelength radio waves)  that are not absorbed by interstellar dust
B)   by observing only the brightest stars in the galaxy
C)   by observing with only the biggest telescopes
D)   by observing with telescopes above the Earth's atmosphere, such as the Hubble Space Telescope
E)   We cannot see through the interstellar medium.

Question 12

Which of the following patterns in the Milky Way structure is consistent with the idea that the Milky Way has not suffered a major collision with another massive galaxy?

Accepted Answer

A)   The halo is full of old stars orbiting in many different directions.
B)   The disk is composed of stars of many different ages.
C)   The disk is composed of stars orbiting in the same plane, same direction.
D)   Globular clusters are compact groups of thousands of stars.

Question 13

If we could watch spiral arms from a telescope situated above the Milky Way over 500 million years, what would we see happen?

Accepted Answer

A)   Stars will move through the spiral arms, bunching up closer as they pass through. Young hot stars will form and die within the arms before having a chance to move out.
B)   The spiral arms will seem to "wind up", to wrap more and more tightly around the center of the Galaxy.
C)   The spiral arms will eventually dissipate and fade away, since they are a temporary phenomenon that should only last for a million years or so.
D)   The spiral arms will eventually unwind, as centripetal forces send the stars flying outwards into intergalactic space.

Question 14

The very first stars in the universe were made of:

Accepted Answer

A)   hydrogen and helium, 10% heavy elements.
B)   hydrogen and helium.
C)   hydrogen and helium, 2% heavy elements.
D)   hydrogen and helium, 0.1% heavy elements.

Question 15

Over time, the star-gas-star cycle leads the gas in the Milky Way to ________.

Accepted Answer

A)   have a greater abundance of heavy elements
B)   have a lower abundance of heavy elements
C)   become denser and have a greater abundance of heavy elements
D)   become denser and hotter

Question 16

How does the interstellar medium affect our view of most of the galaxy?

Accepted Answer

A)   It prevents us from seeing most of the galactic disk with visible and ultraviolet light.
B)   It absorbs all wavelengths of light.
C)   It produces so much visible light that it blocks our view of anything beyond it.
D)   It has no effect on visible-light observations, but prevents us from studying the galactic center with radio waves or X-rays.

Question 17

The star-gas-star cycle will continue forever because stars are continually recycling gas.

Accepted Answer

A) True 
 B)False

Question 18

Suppose you discovered a star made purely of hydrogen and helium. How old do you think it would be? Explain.

Accepted Answer

A star made of only hydrogen and helium ...

Question 19

Approximately how long does it take the Sun to orbit the center of the Milky Way Galaxy?

Accepted Answer

A)   23,000 years
B)   230,000 years
C)   2.3 million years
D)   230 million years
E)   23 billion years

Question 20

What is the thickness of the disk of the Milky Way?

Accepted Answer

A)   100 light years
B)   1,000 light years
C)   10,000 light years
D)   100,000 light years
E)   1,000,000 light years

Exam 14: Our Galaxy

What produces the 21-cm radio line that we can be used to map the Milky Way Galaxy?

Correct AnswerverifiedShow Answer

Fill in the blank: Elements heavier than hydrogen and helium constitute about ________ of the mass of the interstellar medium.

Correct AnswerverifiedShow Answer

Over time, the star-gas-star cycle leads the gas in the Milky Way to ________.

Correct AnswerverifiedShow Answer

How can we see through the interstellar medium?

Correct AnswerverifiedShow Answer

Most of the mass of the Milky Way is located in the halo of the galaxy in the form of dark matter.

Correct AnswerverifiedShow Answer

What do we call the bright, sphere-shaped region of stars that occupies the central few thousand light-years of the Milky Way Galaxy?

Correct AnswerverifiedShow Answer

Which of the following patterns in the Milky Way structure is consistent with the idea that the Milky Way has not suffered a major collision with another massive galaxy?

Correct AnswerverifiedShow Answer

If we could watch spiral arms from a telescope situated above the Milky Way over 500 million years, what would we see happen?

Correct AnswerverifiedShow Answer

Based on observations, which of the following statements about stars in the Milky Way is generally true?

Correct AnswerverifiedShow Answer

Explain why in space, "no one can hear you scream."

Correct AnswerverifiedScreams, and any sound that we make, are...View AnswerShow Answer

The very first stars in the universe were made of:

Correct AnswerverifiedShow Answer

Approximately how long does it take the Sun to orbit the center of the Milky Way Galaxy?

Correct AnswerverifiedShow Answer

Astronomers observe huge bubbles of hot gas, some over a thousand light years across, in the Milky Way. What is their cause?

Correct AnswerverifiedThese huge bubbles, called "superbubbles...View AnswerShow Answer

Suppose you discovered a star made purely of hydrogen and helium. How old do you think it would be? Explain.

Correct AnswerverifiedA star made of only hydrogen and helium ...View AnswerShow Answer

The star-gas-star cycle will continue forever because stars are continually recycling gas.

Correct AnswerverifiedShow Answer

What happens after many generations of the star-gas-star cycle?

Correct AnswerverifiedShow Answer

Suppose you want to observe and study the radiation from gas inside an interstellar bubble created by a supernova. Which of the following observatories will be most useful?

Correct AnswerverifiedShow Answer

Which of the following statements comparing halo stars to our Sun is not true?

Correct AnswerverifiedShow Answer

How does the interstellar medium affect our view of most of the galaxy?

Correct AnswerverifiedShow Answer

What is the thickness of the disk of the Milky Way?

Correct AnswerverifiedShow Answer

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Screams, and any sound that we make, are...
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These huge bubbles, called "superbubbles...
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A star made of only hydrogen and helium ...
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