Question 1

Where are many of the older, metal-poor stars found in the Milky Way Galaxy?

Accepted Answer

A)   throughout the whole Galaxy
B)   at the galactic center
C)   in the disk and spiral arms
D)   in globular clusters and in the galactic halo

Question 2

Where is the Sun located in the Milky Way Galaxy?

Accepted Answer

A)   in the Scutum-Centaurus arm
B)   in the Sagittarius arm
C)   in the Perseus arm
D)   between the Sagittarius and Perseus arms

Question 3

What is the distribution of giant molecular clouds in the Milky Way Galaxy and other similar galaxies?

Accepted Answer

A)   Giant molecular clouds occur primarily in the spiral arms.
B)   Giant molecular clouds are distributed uniformly throughout the disk.
C)   Giant molecular clouds are concentrated close to the galactic center.
D)   Giant molecular clouds are distributed throughout the halo, with greater density toward the center.

Question 4

The major advantages of the 21-cm radio emission from hydrogen gas for investigating the spiral structure of the Milky Way Galaxy are that

Accepted Answer

A)   it is relatively easily absorbed by hydrogen gas in the Milky Way, so measurements are not confused by emission of this radiation from other galaxies beyond the Milky Way. It originates only from cold hydrogen gas and can be used to map this important component.
B)   radio waves easily penetrate the Milky Way dust and gas, and they are a very narrow-wavelength line emission; thus its Doppler shift can be used to measure gas motions.
C)   Doppler shift of this narrow-wavelength line emission is caused by the temperature of the hot hydrogen gas and therefore can be used to measure the distribution and temperature of this important component of the Milky Way.
D)   this emission can easily penetrate the Milky Way gas and dust and comes only from hot gas, hence its ability to be used to map the distribution of hot hydrogen gas.

Question 5

In the eighteenth century, Sir William Herschel used star counts in different regions of the sky along the Milky Way to estimate the position of the center of the Milky Way. He incorrectly concluded that the Sun was close to the center. The reason for this erroneous conclusion was that

Accepted Answer

A)   the redshift of the more distant stars made them invisible to Herschel.
B)   Herschel counted all "stars" in each star field and included many galaxies that were outside the Milky Way, thus confusing the distribution.
C)   the large quantity of absorbing dust between stars obscured the more distant regions of the Galaxy.
D)   emissions from hot hydrogen gas clouds served to hide the more distant stars, localizing his search.

Question 6

The plane of the Milky Way Galaxy is filled with clouds of gas and dust. To receive information from objects embedded in these clouds astronomers use receivers sensitive in these ranges EXCEPT

Accepted Answer

A)   ultraviolet.
B)   X-ray.
C)   infrared.
D)   radio.

Question 7

In order to measure the speed of the Sun, one must have a rest frame to use as a reference. What rest frame is used for this measurement?

Accepted Answer

A)   the average velocity of nearby galaxies
B)   the black hole at the galactic center
C)   the average velocity of the globular clusters
D)   cosmic background radiation

Question 8

Trumpler discovered the effect of interstellar dust by comparing two different distance measurements of distant clusters. The first was based on appearance (concentration of stars toward the center, etc.) , which was unaffected by dust. The other was spectroscopic parallax (use of the H-R diagram) , which was affected by dust. What should such a comparison show?

Accepted Answer

A)   The H-R diagram should always give larger distances.
B)   The H-R diagram should always give smaller distances.
C)   There should be no difference in the distances.
D)   The distances should be different, but sometimes the H-R diagram should give the larger distance and sometimes the smaller distance depending on the actual distance to the cluster.

Question 9

Much of the mass of the Milky Way Galaxy appears to be in the form of "dark matter" of unknown composition. At present, dark matter can be detected only because

Accepted Answer

A)   it emits synchrotron radiation at radio wavelengths.
B)   its gravitational pull affects orbital motions in the Galaxy.
C)   it bends light from distant quasars.
D)   it blocks out the light from distant stars in the plane of the Galaxy.

Question 10

How do astronomers obtain an estimate of the amount of mass that is inside the Sun's orbital path in the Milky Way Galaxy?

Accepted Answer

A)   by counting stars, assuming an average stellar mass, and calculating the total mass
B)   by observing the bending of light from distant galaxies as the light passes near the center of the Milky Way
C)   by observing the movement of the Galaxy toward neighboring galaxies because of mutual gravitational attraction
D)   by applying Kepler's law to the motion of the Sun and other nearby stars

Question 11

For which one of these objects has the phenomenon of differential rotation NOT been observed?

Accepted Answer

A)   Mars
B)   Jupiter
C)   Sun
D)   Milky Way Galaxy

Question 12

The star S2 orbits Sagittarius A* (the galactic center of the Milky Way)  with a period of 15.2 years and a semimajor axis of 950 au. What does Kepler's third law suggest as the total amount of mass inside the orbital radius of S2?

Accepted Answer

A)   1.3 * 106 solar masses
B)   2.6 * 106 solar masses
C)   3.7 *106 solar masses
D)   9.4* 106 solar masses

Question 13

Which of these statistics is NOT useful for mapping the locations and shapes of the spiral arms of the Milky Way Galaxy?

Accepted Answer

A)   distribution of globular clusters
B)   distribution of O and B stars
C)   distribution of emission nebulae (H II regions) 
D)   distribution of giant molecular clouds

Question 14

One curious fact about the Milky Way Galaxy, discovered in the past two decades, is that

Accepted Answer

A)   a significant fraction of its mass is in the form of globular clusters, distributed in a spherical halo centered on the galactic center.
B)   a large black hole is slowly clearing out the mass near the galactic center, leaving a cold, dark void.
C)   enormous amounts of energy are pouring out of a compact but very massive source at its center.
D)   most of its mass is in the spiral arms extending out into space.

Question 15

Cepheid variable stars are invaluable in astronomy because of the close relationship between

Accepted Answer

A)   the peak wavelength of their spectra and their surface temperatures.
B)   their luminosity, or absolute magnitude, and their pulsation period.
C)   the redshift of their spectra and their distance from the Sun.
D)   their apparent magnitude and their pulsation period.

Question 16

Where are bright, young O and B stars MOST likely to be found in the Milky Way Galaxy?

Accepted Answer

A)   inside the spiral arms
B)   in globular clusters
C)   in the outermost regions of the disk, where much of the "dark matter" is located
D)   between the spiral arms, where there is less absorbing material

Question 17

What useful purpose did variable stars serve for Harlow Shapley in locating the galactic center?

Accepted Answer

A)   Variable stars are important spiral arm tracers and thus defined the shape of the Milky Way Galaxy.
B)   The brightness variations of variable stars allowed accurate distances to be measured.
C)   Variable stars emit copious amounts of infrared radiation and are thus visible through interstellar dust that obscures visible light.
D)   Variable stars are concentrated in the galactic center and so defined its direction.

Question 18

In the 1920s Edwin Hubble began answering the question about the nature of spiral "nebulae" when he discovered Cepheid variables in

Accepted Answer

A)   the Milky Way Galaxy.
B)   the Whirlpool Galaxy (M51) .
C)   the Andromeda Galaxy (M31) .
D)   the Small Magellanic Cloud.

Question 19

The presence of a supermassive black hole at the center of the Milky Way Galaxy has been deduced from

Accepted Answer

A)   gravitational radiation emitted by stars as they are swallowed by the black hole.
B)   powerful magnetic fields in the huge filaments arching away from (or toward)  the center.
C)   the number of globular clusters that concentrate toward the galactic center.
D)   the very high orbital speed of stars orbiting the galactic center.

Question 20

Variable stars such as Cepheid variables are used in what important measurement in astronomy?

Accepted Answer

A)   measurement of the distances to stars
B)   measurement of the rotation speeds of galaxies
C)   measurement of the surface temperatures of stars
D)   keeping of accurate time

Exam 16: The Milky Way Galaxy

One curious fact about the Milky Way Galaxy, discovered in the past two decades, is that

Correct Answer
verified

Where are many of the older, metal-poor stars found in the Milky Way Galaxy?

Correct Answer
verified

What is the distribution of giant molecular clouds in the Milky Way Galaxy and other similar galaxies?

Correct Answer
verified

The plane of the Milky Way Galaxy is filled with clouds of gas and dust. To receive information from objects embedded in these clouds astronomers use receivers sensitive in these ranges EXCEPT

Correct Answer
verified

Which of these statistics is NOT useful for mapping the locations and shapes of the spiral arms of the Milky Way Galaxy?

Correct Answer
verified

What useful purpose did variable stars serve for Harlow Shapley in locating the galactic center?

Correct Answer
verified

The star S2 orbits Sagittarius A* (the galactic center of the Milky Way) with a period of 15.2 years and a semimajor axis of 950 au. What does Kepler's third law suggest as the total amount of mass inside the orbital radius of S2?

Correct Answer
verified

For which one of these objects has the phenomenon of differential rotation NOT been observed?

Correct Answer
verified

How do astronomers obtain an estimate of the amount of mass that is inside the Sun's orbital path in the Milky Way Galaxy?

Correct Answer
verified

The major advantages of the 21-cm radio emission from hydrogen gas for investigating the spiral structure of the Milky Way Galaxy are that

Correct Answer
verified

In the eighteenth century, Sir William Herschel used star counts in different regions of the sky along the Milky Way to estimate the position of the center of the Milky Way. He incorrectly concluded that the Sun was close to the center. The reason for this erroneous conclusion was that

Correct Answer
verified

In the 1920s Edwin Hubble began answering the question about the nature of spiral "nebulae" when he discovered Cepheid variables in

Correct Answer
verified

The presence of a supermassive black hole at the center of the Milky Way Galaxy has been deduced from

Correct Answer
verified

Correct Answer
verified

Much of the mass of the Milky Way Galaxy appears to be in the form of "dark matter" of unknown composition. At present, dark matter can be detected only because

Correct Answer
verified

In order to measure the speed of the Sun, one must have a rest frame to use as a reference. What rest frame is used for this measurement?

Correct Answer
verified

Where are bright, young O and B stars MOST likely to be found in the Milky Way Galaxy?

Correct Answer
verified

Cepheid variable stars are invaluable in astronomy because of the close relationship between

Correct Answer
verified

Where is the Sun located in the Milky Way Galaxy?

Correct Answer
verified

Variable stars such as Cepheid variables are used in what important measurement in astronomy?

Correct Answer
verified

Exam 16: The Milky Way Galaxy

One curious fact about the Milky Way Galaxy, discovered in the past two decades, is that

Correct AnswerverifiedShow Answer

Where are many of the older, metal-poor stars found in the Milky Way Galaxy?

Correct AnswerverifiedShow Answer

What is the distribution of giant molecular clouds in the Milky Way Galaxy and other similar galaxies?

Correct AnswerverifiedShow Answer

The plane of the Milky Way Galaxy is filled with clouds of gas and dust. To receive information from objects embedded in these clouds astronomers use receivers sensitive in these ranges EXCEPT

Correct AnswerverifiedShow Answer

Which of these statistics is NOT useful for mapping the locations and shapes of the spiral arms of the Milky Way Galaxy?

Correct AnswerverifiedShow Answer

What useful purpose did variable stars serve for Harlow Shapley in locating the galactic center?

Correct AnswerverifiedShow Answer

The star S2 orbits Sagittarius A* (the galactic center of the Milky Way) with a period of 15.2 years and a semimajor axis of 950 au. What does Kepler's third law suggest as the total amount of mass inside the orbital radius of S2?

Correct AnswerverifiedShow Answer

For which one of these objects has the phenomenon of differential rotation NOT been observed?

Correct AnswerverifiedShow Answer

How do astronomers obtain an estimate of the amount of mass that is inside the Sun's orbital path in the Milky Way Galaxy?

Correct AnswerverifiedShow Answer

The major advantages of the 21-cm radio emission from hydrogen gas for investigating the spiral structure of the Milky Way Galaxy are that

Correct AnswerverifiedShow Answer

In the eighteenth century, Sir William Herschel used star counts in different regions of the sky along the Milky Way to estimate the position of the center of the Milky Way. He incorrectly concluded that the Sun was close to the center. The reason for this erroneous conclusion was that

Correct AnswerverifiedShow Answer

In the 1920s Edwin Hubble began answering the question about the nature of spiral "nebulae" when he discovered Cepheid variables in

Correct AnswerverifiedShow Answer

The presence of a supermassive black hole at the center of the Milky Way Galaxy has been deduced from

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Much of the mass of the Milky Way Galaxy appears to be in the form of "dark matter" of unknown composition. At present, dark matter can be detected only because

Correct AnswerverifiedShow Answer

In order to measure the speed of the Sun, one must have a rest frame to use as a reference. What rest frame is used for this measurement?

Correct AnswerverifiedShow Answer

Where are bright, young O and B stars MOST likely to be found in the Milky Way Galaxy?

Correct AnswerverifiedShow Answer

Cepheid variable stars are invaluable in astronomy because of the close relationship between

Correct AnswerverifiedShow Answer

Where is the Sun located in the Milky Way Galaxy?

Correct AnswerverifiedShow Answer

Variable stars such as Cepheid variables are used in what important measurement in astronomy?

Correct AnswerverifiedShow Answer

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