Question 1

Which kind of star is highly unlikely to be found in the halo of the Milky Way?

Accepted Answer

A)  G star
B)  K star
C)  M star
D)  O starE) A) and B)
F) A) and C)

Question 2

Over time, what is the net effect of the star- gas- star cycle in the Milky Way?

Accepted Answer

A)  The total mass in the galaxy's interstellar medium is gradually increased, and the new gas is continually enriched in heavy elements.
B)  The gas of the interstellar medium is continually depleted in elements heavier than helium.
C)  The temperature of the interstellar medium varies between the cool 10- 50 degrees (Kelvin) required to form stars and the 2000- 30,000 degree (Kelvin) temperatures of the outer layers of the stars that form. But over time, more and more of the interstellar medium remains cool.
D)  The total mass in the galaxy's interstellar medium is gradually reduced, and the remaining gas is continually enriched in heavy elements.
E)  There is no net effect to the cycle. Mass in the interstellar medium lost to star formation is exactly replaced by stellar winds and supernova explosions.F) C) and D)
G) B) and D)

Question 3

What are the Magellanic Clouds?

Accepted Answer

A)  star- forming clouds found in the constellation Orion
B)  the clouds of dust and gas found interspersed in many places throughout the Milky Way Galaxy
C)  two nebulae located in the disk of the Milky Way galaxy and visible only from the Southern Hemisphere
D)  two small galaxies that orbit the Milky Way GalaxyE) None of the above
F) A) and D)

Question 4

If we could see our own galaxy from 2 million light- years away, it would appear _ .

Accepted Answer

A)  as a faintly glowing band of light stretching all the way around the sky
B)  as a flattened disk with a central bulge and spiral arms
C)  to fill the sky with widely spaced stars
D)  like a single, dim starE) All of the above
F) A) and C)

Question 5

Which star is older?

Accepted Answer

A)  an A star in the globular cluster M13
B)  an M star in the globular cluster M13
C)  Both stars (the A and M star) are the same age.D) B) and C)
E) All of the above

Question 6

Inferring cloud properties using carbon- monoxide: At the low temperatures of molecular clouds, carbon monoxide emits radio light more strongly than does molecular hydrogen. What assumptions must be made to then use observations of carbon monoxide to infer the properties of the cloud as a whole?

Accepted Answer

The hydrogen- to- CO ratio mus...

Question 7

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

Accepted Answer

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

Question 8

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 9

What evidence supports the existence of a black hole at the center of our galaxy?

Accepted Answer

A)  The motions of the gas and stars at the center indicate that it contains 4 million solar masses within a region only 3 light- years across.
B)  We can see gas falling into an accretion disk and past the event horizon of a black hole.
C)  We observe a large, dark object that absorbs all light at the center of our galaxy.
D)  We observe an extremely bright X- ray source at the center of our galaxy.
E)  All of the aboveF) None of the above
G) A) and B)

Question 10

Modified Newtonian Dynamics? The case for dark matter in the Milky Way can be viewed as a failure of stars and gas far from the galactic center to obey Newton's law of gravitational attraction-- that is, the stars and gas seem to orbit too quickly for the visible matter their orbits enclose. Why do you think that astronomers choose to "save" Newton's form of gravitational attraction by postulating unseen dark matter, as opposed to regarding the observed orbital motion as a falsification of Newtonian gravitation on the scale of the Milky Way? [Note: At the distance scales involved, the gravitational forces in the galaxy are all fairly weak, much weaker than those encountered in a neutron star or black hole, and hence Einstein's theory of gravity (General Relativity)gives the same predictions as Newton's gravitational law].

Accepted Answer

The question you've posed touches on a s...

Question 11

Why do spiral arms have a blue color?

Accepted Answer

Spiral arms are waves of enhanced densit...

Question 12

Red and orange stars are found evenly spread throughout the galactic disk, but blue stars are typically found .

Accepted Answer

A)  only in the central bulge
B)  only in or near star- forming clouds
C)  in the halo
D)  also evenly spread throughout the galactic diskE) All of the above
F) A) and D)

Question 13

Spectra for the Cygnus loop and the Orion nebula are shown above. Which of these is seen in the Orion nebula, but is not clearly visible in the Cygnus loop spectrum?

Accepted Answer

A)  atomic hydrogen
B)  atomic helium
C)  ionized oxygen
D)  ionized sulfurE) None of the above
F) B) and D)

Question 14

The primary way that we observe the atomic hydrogen that makes up most of the interstellar gas in the Milky Way is with _.

Accepted Answer

A)  space- based ultraviolet telescopes
B)  X- ray telescopes
C)  ground- based visible- light telescopes
D)  radio telescopes observing at a wavelength of 21 centimetersE) A) and D)
F) A) and B)

Question 15

Briefly explain why stars that formed early in the history of the galaxy contain a smaller proportion of heavy elements than stars that formed more recently.

Accepted Answer

The star- gas- star cycle gradually enri...

Question 16

How did star formation likely proceed in the protogalactic cloud that formed the Milky Way?

Accepted Answer

A)  The protogalactic cloud gradually formed stars, starting from the outer edges of the spiral arms and working inward.
B)  The protogalactic cloud gradually formed stars, starting from the center of the galaxy working outwards.
C)  The stars that formed first could orbit the center of the galaxy in any direction at any inclination.
D)  The stars that formed first eventually settled into a galactic disk, circling the center of the galaxy.E) A) and B)
F) None of the above

Question 17

Why has star formation ceased in the galactic halo?

Accepted Answer

A)  All of the galaxy's cool gas settled to the galactic plane long ago.
B)  All the halo gas consists of elements with more protons than helium.
C)  There are no white dwarf binaries to trigger star formation via their supernovae.
D)  The halo has no gas at all.E) A) and B)
F) C) and D)

Question 18

What is Sgr A×?

Accepted Answer

A)  the brightest star in the constellation Sagittarius
B)  the bulge at the center of our galaxy
C)  a source of bright radio emission in the center of our galaxy
D)  a source of bright X- ray emission coming from the entire constellation of Sagittarius
E)  a source of bright ultraviolet light near the center of our galaxyF) D) and E)
G) B) and E)

Question 19

Which of the following are signposts of the presence of high mass stars, and thus recent star formation?

Accepted Answer

A)  closely spaced low mass stars
B)  predominantly red ionization nebulae
C)  predominantly blue reflection nebulae
D)  A and C
E)  B and CF) B) and E)
G) A) and E)

Question 20

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

Accepted Answer

A)  Molecules in the interstellar medium absorb all wavelengths of light.
B)  Hydrogen gas produces so much visible light that the interstellar medium is opaque, blocking our view of anything beyond it.
C)  The small mixture of dust grains in the interstellar medium absorbs visible light.
D)  Dust reflects most light from distant regions of the galaxy back towards the source.
E)  all of the aboveF) B) and D)
G) A) and B)

Exam 15: Our Galaxy

Which kind of star is highly unlikely to be found in the halo of the Milky Way?

Correct Answer
verified

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

Correct Answer
verified
Screams, and any sound that we make, are...
View Answer

Why do spiral arms have a blue color?

Correct Answer
verified
Spiral arms are waves of enhanced densit...
View Answer

What is Sgr A×?

Correct Answer
verified

What evidence supports the existence of a black hole at the center of our galaxy?

Correct Answer
verified

What are the Magellanic Clouds?

Correct Answer
verified

Spectra for the Cygnus loop and the Orion nebula are shown above. Which of these is seen in the Orion nebula, but is not clearly visible in the Cygnus loop spectrum?

Correct Answer
verified

How did star formation likely proceed in the protogalactic cloud that formed the Milky Way?

Correct Answer
verified

Which of the following are signposts of the presence of high mass stars, and thus recent star formation?

Correct Answer
verified

If we could see our own galaxy from 2 million light- years away, it would appear _ .

Correct Answer
verified

The primary way that we observe the atomic hydrogen that makes up most of the interstellar gas in the Milky Way is with _.

Correct Answer
verified

Briefly explain why stars that formed early in the history of the galaxy contain a smaller proportion of heavy elements than stars that formed more recently.

Correct Answer
verified
The star- gas- star cycle gradually enri...
View Answer

Over time, what is the net effect of the star- gas- star cycle in the Milky Way?

Correct Answer
verified

Inferring cloud properties using carbon- monoxide: At the low temperatures of molecular clouds, carbon monoxide emits radio light more strongly than does molecular hydrogen. What assumptions must be made to then use observations of carbon monoxide to infer the properties of the cloud as a whole?

Correct Answer
verified
The hydrogen- to- CO ratio mus...
View Answer

Why has star formation ceased in the galactic halo?

Correct Answer
verified

Red and orange stars are found evenly spread throughout the galactic disk, but blue stars are typically found .

Correct Answer
verified

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

Correct Answer
verified
These huge bubbles, called "superbubbles...
View Answer

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

Correct Answer
verified

Which star is older?

Correct Answer
verified

Correct Answer
Answered by ExamLex AI
The question you've posed touches on a s...
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Exam 15: Our Galaxy

Which kind of star is highly unlikely to be found in the halo of the Milky Way?

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

Why do spiral arms have a blue color?

Correct AnswerverifiedSpiral arms are waves of enhanced densit...View AnswerShow Answer

What is Sgr A×?

Correct AnswerverifiedShow Answer

What evidence supports the existence of a black hole at the center of our galaxy?

Correct AnswerverifiedShow Answer

What are the Magellanic Clouds?

Correct AnswerverifiedShow Answer

Spectra for the Cygnus loop and the Orion nebula are shown above. Which of these is seen in the Orion nebula, but is not clearly visible in the Cygnus loop spectrum?

Correct AnswerverifiedShow Answer

How did star formation likely proceed in the protogalactic cloud that formed the Milky Way?

Correct AnswerverifiedShow Answer

Which of the following are signposts of the presence of high mass stars, and thus recent star formation?

Correct AnswerverifiedShow Answer

If we could see our own galaxy from 2 million light- years away, it would appear _ .

Correct AnswerverifiedShow Answer

The primary way that we observe the atomic hydrogen that makes up most of the interstellar gas in the Milky Way is with _.

Correct AnswerverifiedShow Answer

Briefly explain why stars that formed early in the history of the galaxy contain a smaller proportion of heavy elements than stars that formed more recently.

Correct AnswerverifiedThe star- gas- star cycle gradually enri...View AnswerShow Answer

Over time, what is the net effect of the star- gas- star cycle in the Milky Way?

Correct AnswerverifiedShow Answer

Inferring cloud properties using carbon- monoxide: At the low temperatures of molecular clouds, carbon monoxide emits radio light more strongly than does molecular hydrogen. What assumptions must be made to then use observations of carbon monoxide to infer the properties of the cloud as a whole?

Correct AnswerverifiedThe hydrogen- to- CO ratio mus...View AnswerShow Answer

Why has star formation ceased in the galactic halo?

Correct AnswerverifiedShow Answer

Red and orange stars are found evenly spread throughout the galactic disk, but blue stars are typically found .

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

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

Correct AnswerverifiedShow Answer

Which star is older?

Correct AnswerverifiedShow Answer

Correct AnswerAnswered by ExamLex AIThe question you've posed touches on a s...View AnswerShow Answer

Correct Answer
verified

Correct Answer
verified
Screams, and any sound that we make, are...
View Answer

Correct Answer
verified
Spiral arms are waves of enhanced densit...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
The star- gas- star cycle gradually enri...
View Answer

Correct Answer
verified

Correct Answer
verified
The hydrogen- to- CO ratio mus...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified
These huge bubbles, called "superbubbles...
View Answer

Correct Answer
verified

Correct Answer
verified

Correct Answer
Answered by ExamLex AI
The question you've posed touches on a s...
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