Question 1

The Milky Way has both a thin and thick disk of stars. Which one of the following statements about them is FALSE?

Accepted Answer

A)   The thin disk stars on average are younger than the thick disk stars.
B)   Molecular clouds are distributed more like the thin disk stars rather than the thick disk stars.
C)   The thin disk stars on average have lower abundances of heavy elements than the thick disk stars.
D)   The thick disk stars may be older thin disk stars that have higher upward velocities because they have gravitationally interacted more with molecular clouds in the spiral arms.
E)   The thick disk may have formed when a small dwarf galaxy merged with the Milky Way.

Question 2

You measure the chemical abundances and space motions of stars near the Sun, and plot your data in the figure shown below. The stars separate into two distinct groups, which you label A and B. These groups are, respectively, in which two stellar components of the Milky Way?

Accepted Answer

A)   disk and halo
B)   bulge and disk
C)   halo and disk
D)   halo and bulge
E)   globular clusters and halo

Question 3

There are many more individual stars residing in the Milky Way stellar halo than inside globular clusters.

Accepted Answer

A) True 
 B)False

Question 4

The Milky Way appears as __________ in the night sky because __________.

Accepted Answer

A)   randomly distributed stars; the Sun lies near the center of the Milky Way
B)   a faint band of light sprinkled with dark clouds; the Sun lies in the disk
C)   a faint band of light; the Sun lies in the halo
D)   an ellipse of light in the Southern sky; the Sun lies midway along the disk
E)   a circular disk with spiral arms; the Sun lies far above the galaxy's plane

Question 5

If the central black hole started accreting a lot of gas, it would appear as what kind of an object?

Accepted Answer

A)   a red supergiant
B)   a pulsar
C)   a planetary nebula
D)   an AGN
E)   a supernova remnant

Question 6

The Milky Way Galaxy is a(n)  __________ galaxy.

Accepted Answer

A)   irregular
B)   elliptical
C)   nonbarred spiral
D)   barred spiral
E)   lenticular D

Question 7

What observed property of the Milky Way suggests that it contains a large amount of matter not in the form of stars?

Accepted Answer

A)   the rotation curve
B)   the velocities of the open star clusters
C)   the number and shape of the spiral arms
D)   the thickness of the disk
E)   the presence of a black hole at the galactic center

Question 8

The locations of globular clusters on the sky and their distances tell us that the Sun is located near the center of the Milky Way.

Accepted Answer

A) True 
 B)False

Question 9

Magnetic fields in the Milky Way are concentrated in the disk because:

Accepted Answer

A)   halo stars are incapable of producing strong magnetic fields
B)   the fields are tied to the charged particles in dense molecular clouds
C)   gravity forces them to sink to the center of the disk
D)   supernovae explosions continually force them toward the middle of the disk
E)   supernovae explosions eliminate magnetic fields away from the disk B

Question 10

Why is 21-cm radiation the best way to map the spiral arms in the Milky Way?

Accepted Answer

A)   The molecular hydrogen gas that produces this emission is concentrated in the spiral arms.
B)   These photons, which are produced by neutral hydrogen, pass through the dense clouds of gas and dust in the disk.
C)   The emission is produced by supernovae, which are concentrated in the spiral arms.
D)   Radio telescopes are easier to operate than optical telescopes, and observations can be made even during the daytime.
E)   Radio photons do not have Doppler shifts, so we can detect clouds of gas without having to worry about the orbital velocities.

Question 11

Why do we know that at least one generation of stars formed and died before the Milky Way's globular clusters formed?

Accepted Answer

A)   All globular cluster stars have some amount of heavy elements.
B)   They are so old that nuclear fusion in globular cluster stars has altered their chemical abundances.
C)   Globular clusters are 9 to 10 billion years old.
D)   No globular cluster is older than 12 billion years.
E)   All globular clusters reside in the disk of the Milky Way.

Question 12

Our galaxy is __________ other galaxies because the dark matter in the Milky Way __________.

Accepted Answer

A)   unlike; makes up a small fraction of the total mass than in other galaxies
B)   unlike; makes up a larger fraction of the total mass than in other galaxies
C)   like; contains most of the mass in the galaxy
D)   like; is made up of black holes and other stellar remnants
E)   like; is made up of dust and faint objects of planetary mass

Question 13

Explain how a standard candle allows you to determine the distance to an object. What is it that you have to measure or know about the standard candle to derive its distance?

Accepted Answer

A standard candle is a star that can be ...

Question 14

In the Milky Way's outermost halo, the stars orbit:

Accepted Answer

A)   mostly in the prograde direction
B)   mostly in the retrograde direction
C)   both in the prograde and retrograde directions
D)   the same way the disk stars do
E)   neither in the prograde nor the retrograde directions C

Question 15

If RR Lyrae stars in a globular cluster had an apparent magnitude of 11.5 and an absolute magnitude of 0.5, what would the globular cluster's distance be?

Accepted Answer

A)   1,600 pc
B)   1,900 pc
C)   2,500 pc
D)   3,200 pc
E)   8,600 pc

Question 16

What type of standard candle is used to determine distances to globular clusters?

Accepted Answer

A)   O-type main-sequence stars
B)   Cepheid variable stars
C)   T Tauri stars
D)   Type I supernovae
E)   RR Lyrae stars

Question 17

The oldest stars in the galaxy are usually __________ in heavy elements because __________.

Accepted Answer

A)   low; they have had time to accrete unprocessed gas from the interstellar medium
B)   low; they were formed before much chemical enrichment had taken place
C)   low; old stars must have low mass, and low-mass stars do not generate many heavy elements
D)   high; they have turned a lot of their initial hydrogen and helium into heavier elements
E)   high; stars with higher fractions of heavy elements have shorter lifetimes

Question 18

In which part of the Milky Way would you find little or no neutral hydrogen, no current star formation, and stars that are all older than 10 billion years?

Accepted Answer

A)   the inner disk
B)   the outer disk
C)   the galactic center
D)   the solar neighborhood
E)   the halo

Question 19

Where are the most metal-rich stars found in the Milky Way?

Accepted Answer

A)   in the disk near the Sun
B)   near the center
C)   in the halo
D)   in globular clusters
E)   in old open clusters

Question 20

What objects are used to determine that the galaxy is mostly dark matter?

Accepted Answer

The presence of dark matter is indicated...

Exam 21: The Milky Waya Normal Spiral Galaxy

The Milky Way has both a thin and thick disk of stars. Which one of the following statements about them is FALSE?

Correct AnswerverifiedShow Answer

You measure the chemical abundances and space motions of stars near the Sun, and plot your data in the figure shown below. The stars separate into two distinct groups, which you label A and B. These groups are, respectively, in which two stellar components of the Milky Way?

Correct AnswerverifiedShow Answer

There are many more individual stars residing in the Milky Way stellar halo than inside globular clusters.

Correct AnswerverifiedShow Answer

The Milky Way appears as __________ in the night sky because __________.

Correct AnswerverifiedShow Answer

If the central black hole started accreting a lot of gas, it would appear as what kind of an object?

Correct AnswerverifiedShow Answer

The Milky Way Galaxy is a(n) __________ galaxy.

Correct AnswerverifiedD

What observed property of the Milky Way suggests that it contains a large amount of matter not in the form of stars?

Correct AnswerverifiedShow Answer

The locations of globular clusters on the sky and their distances tell us that the Sun is located near the center of the Milky Way.

Correct AnswerverifiedShow Answer

Magnetic fields in the Milky Way are concentrated in the disk because:

Correct AnswerverifiedB

Why is 21-cm radiation the best way to map the spiral arms in the Milky Way?

Correct AnswerverifiedShow Answer

Why do we know that at least one generation of stars formed and died before the Milky Way's globular clusters formed?

Correct AnswerverifiedShow Answer

Our galaxy is __________ other galaxies because the dark matter in the Milky Way __________.

Correct AnswerverifiedShow Answer

Explain how a standard candle allows you to determine the distance to an object. What is it that you have to measure or know about the standard candle to derive its distance?

Correct AnswerverifiedA standard candle is a star that can be ...View AnswerShow Answer

In the Milky Way's outermost halo, the stars orbit:

Correct AnswerverifiedC

If RR Lyrae stars in a globular cluster had an apparent magnitude of 11.5 and an absolute magnitude of 0.5, what would the globular cluster's distance be?

Correct AnswerverifiedShow Answer

What type of standard candle is used to determine distances to globular clusters?

Correct AnswerverifiedShow Answer

The oldest stars in the galaxy are usually __________ in heavy elements because __________.

Correct AnswerverifiedShow Answer

In which part of the Milky Way would you find little or no neutral hydrogen, no current star formation, and stars that are all older than 10 billion years?

Correct AnswerverifiedShow Answer

Where are the most metal-rich stars found in the Milky Way?

Correct AnswerverifiedShow Answer

What objects are used to determine that the galaxy is mostly dark matter?

Correct AnswerverifiedThe presence of dark matter is indicated...View AnswerShow Answer

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The Milky Way appears as in the night sky because .

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D

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B

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Our galaxy is other galaxies because the dark matter in the Milky Way .

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A standard candle is a star that can be ...
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C

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The oldest stars in the galaxy are usually in heavy elements because .

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The presence of dark matter is indicated...
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