Question 1

Cygnus A,a strong radio source,is also designated 3C 405.What does the "3C" stand for?

Accepted Answer

A)  "3C" stands for the Third Cambridge Catalog, an important list of radio sources. 
B)  This radio source is a Type 3C radio source as opposed to a Type 1A or a Type 2B. 
C)  Cygnus A was discovered through a joint program run by Cambridge, Connecticut, and Calgary Universities. 
D)  A chopper is a device needed to cut off and delineate a signal from a source, and three such choppers are required to isolate an intelligible signal from Cygnus A. 
A)  "3C" stands for the Third Cambridge Catalog, an important list of radio sources. 
B)  This radio source is a Type 3C radio source as opposed to a Type 1A or a Type 2B. 
C)  Cygnus A was discovered through a joint program run by Cambridge, Connecticut, and Calgary Universities. 
D)  A chopper is a device needed to cut off and delineate a signal from a source, and three such choppers are required to isolate an intelligible signal from Cygnus A.

Question 2

The MOST important reason globular clusters are useful for finding the speed of the Sun in its orbit around the Milky Way is that:

Accepted Answer

A)  globular clusters are bright and easily seen at large distances. 
B)  globular clusters on average rotate at the same speed as the Sun around the center of the Galaxy. 
C)  globular clusters are distributed uniformly around the Galaxy. 
D)  the average velocity of all the globular clusters must be zero if the globulars are to maintain their orbits around the galactic center. 
A)  globular clusters are bright and easily seen at large distances. 
B)  globular clusters on average rotate at the same speed as the Sun around the center of the Galaxy. 
C)  globular clusters are distributed uniformly around the Galaxy. 
D)  the average velocity of all the globular clusters must be zero if the globulars are to maintain their orbits around the galactic center.

Question 3

What mechanism is believed to produce flocculent spiral galaxies?

Accepted Answer

A)  satellite galaxies plunging through the disk of the nuclear spiral galaxy 
B)  self-propagating star formation, where star formation occurs in bursts 
C)  shock waves from explosive star formation in the nuclear bulge 
D)  density waves in the interstellar medium 
A)  satellite galaxies plunging through the disk of the nuclear spiral galaxy 
B)  self-propagating star formation, where star formation occurs in bursts 
C)  shock waves from explosive star formation in the nuclear bulge 
D)  density waves in the interstellar medium

Question 4

In a spiral galaxy,the:

Accepted Answer

A)  spiral arm tightness is independent of the size of the nuclear bulge; a particular bulge can have a wide range of spiral structure. 
B)  smaller the nuclear bulge, the tighter the spiral. 
C)  tighter the spiral, the larger the nuclear bulge. 
D)  larger the nuclear bulge, the looser the spiral. 
A)  spiral arm tightness is independent of the size of the nuclear bulge; a particular bulge can have a wide range of spiral structure. 
B)  smaller the nuclear bulge, the tighter the spiral. 
C)  tighter the spiral, the larger the nuclear bulge. 
D)  larger the nuclear bulge, the looser the spiral.

Question 5

The high redshifts seen for quasars could also be interpreted as nearby objects with high Doppler shifts caused by rapid motion.Why has this interpretation generally been rejected?

Accepted Answer

A)  These velocities would exceed the speed of light. 
B)  The relativistic mass increase and length contraction for objects at these speeds would result in densities that would make these objects black holes-and they would then be invisible. 
C)  Such motions through the interstellar gas in a galaxy would create a huge outburst of X rays, and this is not seen. 
D)  Such motions would be large enough to make these objects no longer bound to their galaxies. 
A)  These velocities would exceed the speed of light. 
B)  The relativistic mass increase and length contraction for objects at these speeds would result in densities that would make these objects black holes-and they would then be invisible. 
C)  Such motions through the interstellar gas in a galaxy would create a huge outburst of X rays, and this is not seen. 
D)  Such motions would be large enough to make these objects no longer bound to their galaxies.

Question 6

The present estimate for the total mass of the Milky Way Galaxy in units of solar mass is about:

Accepted Answer

A)  2.3 × 10⁸. 
B)  10¹². 
C)  1.1 × 10¹¹. 
D)  10⁶⁶. 
A)  2.3 × 10⁸. 
B)  10¹². 
C)  1.1 × 10¹¹. 
D)  10⁶⁶.

Question 7

Which parameter representing the motion of the material in the spiral arm of a galaxy is approximately constant and should lead to spiral structure in a galaxy?

Accepted Answer

A)  linear velocity 
B)  inverse of the linear velocity 
C)  rotational period around the galactic center 
D)  product (velocity)² × (distance to galactic center), following a law equivalent to Kepler's third law for the planets 
A)  linear velocity 
B)  inverse of the linear velocity 
C)  rotational period around the galactic center 
D)  product (velocity)² × (distance to galactic center), following a law equivalent to Kepler's third law for the planets

Question 8

An astronomer studying a distant cluster of galaxies finds that several of the galaxies are spiral-shaped,with a nuclear region of moderate size and moderately wound arms.How should the astronomer classify these galaxies?

Accepted Answer

A)  SBa 
B)  Sc 
C)  Sb 
D)  Sa 
A)  SBa 
B)  Sc 
C)  Sb 
D)  Sa

Question 9

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

Accepted Answer

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

Question 10

What is a rich cluster of galaxies?

Accepted Answer

A)  a cluster with more spiral galaxies than ellipticals 
B)  a cluster (like our Local Group) that contains at least two large galaxies 
C)  a cluster with a high metal content 
D)  a cluster containing thousands of galaxies 
A)  a cluster with more spiral galaxies than ellipticals 
B)  a cluster (like our Local Group) that contains at least two large galaxies 
C)  a cluster with a high metal content 
D)  a cluster containing thousands of galaxies

Question 11

Among any number of questions about our Galaxy,which is one for which we have an answer at the present time?

Accepted Answer

A)  Did the central black hole form first, or did the Galaxy form first? 
B)  Does the Galaxy have a central bar or not? 
C)  Was the Milky Way Galaxy formed by the merger of smaller galaxies? 
D)  What is heating the gas at the center of the Galaxy to 100 million K? 
A)  Did the central black hole form first, or did the Galaxy form first? 
B)  Does the Galaxy have a central bar or not? 
C)  Was the Milky Way Galaxy formed by the merger of smaller galaxies? 
D)  What is heating the gas at the center of the Galaxy to 100 million K?

Question 12

Who first showed that the recessional speeds of galaxies increase with increasing distance from Earth?

Accepted Answer

A)  V. M. Slipher 
B)  Karl Jansky 
C)  Edwin Hubble 
D)  Albert Einstein 
A)  V. M. Slipher 
B)  Karl Jansky 
C)  Edwin Hubble 
D)  Albert Einstein

Question 13

One of the recently discovered components of clusters of galaxies that may have some bearing on the dark matter problem is:

Accepted Answer

A)  large numbers of cool, dark, brown dwarf stars, previously unknown, in the galaxies. 
B)  X-ray measurements of substantial amounts of very hot intergalactic gas in clusters. 
C)  a tremendous flux of neutrinos, which have recently been shown to have mass, coming from these clusters. 
D)  large numbers of small but massive black holes within every galaxy. 
A)  large numbers of cool, dark, brown dwarf stars, previously unknown, in the galaxies. 
B)  X-ray measurements of substantial amounts of very hot intergalactic gas in clusters. 
C)  a tremendous flux of neutrinos, which have recently been shown to have mass, coming from these clusters. 
D)  large numbers of small but massive black holes within every galaxy.

Question 14

In which direction(s)is/are the jets of matter ejected from a supermassive black hole to produce the many effects surrounding quasars and active galaxies?

Accepted Answer

A)  two opposite directions perpendicular to the accretion disk of the black hole 
B)  a single direction above the accretion disk, the precession of which sweeps the jet along the surface of a cone 
C)  two opposite directions across the accretion disk and rotating with it 
D)  tangential to the accretion disk in two opposite directions, 180° apart, with matter being spun off by the rapid disk rotation 
A)  two opposite directions perpendicular to the accretion disk of the black hole 
B)  a single direction above the accretion disk, the precession of which sweeps the jet along the surface of a cone 
C)  two opposite directions across the accretion disk and rotating with it 
D)  tangential to the accretion disk in two opposite directions, 180° apart, with matter being spun off by the rapid disk rotation

Question 15

A moving electron in a magnetic field in space follows a spiral pattern,emitting what type of radiation as it does so?

Accepted Answer

A)  synchrotron radiation 
B)  no radiation at all since it is moving smoothly without acceleration 
C)  Cerenkov radiation 
D)  Lyman radiation 
A)  synchrotron radiation 
B)  no radiation at all since it is moving smoothly without acceleration 
C)  Cerenkov radiation 
D)  Lyman radiation

Question 16

Which parameter is plotted as a function of distance from the galactic center in a rotation curve of a galaxy?

Accepted Answer

A)  the mass of matter inside the distance from the galactic center 
B)  the thickness of the galactic disk 
C)  the mass of cool hydrogen gas 
D)  the speed of stars orbiting the galactic center 
A)  the mass of matter inside the distance from the galactic center 
B)  the thickness of the galactic disk 
C)  the mass of cool hydrogen gas 
D)  the speed of stars orbiting the galactic center

Question 17

In order to measure the speed of the Sun with respect to the center of the galaxy,it was necessary to establish a rest frame.What was used to establish this frame?

Accepted Answer

A)  the average of several nearby galaxies 
B)  the globular clusters in the halo because they remain at rest while the galaxy rotates beneath 
C)  the globular clusters in the halo because their velocities must average to zero 
D)  the Great Attractor because its enormous mass acts like a stationary point 
A)  the average of several nearby galaxies 
B)  the globular clusters in the halo because they remain at rest while the galaxy rotates beneath 
C)  the globular clusters in the halo because their velocities must average to zero 
D)  the Great Attractor because its enormous mass acts like a stationary point

Question 18

As much as 90% of the matter in the universe may be unseen "dark matter." Where is this dark matter?

Accepted Answer

A)  Dark matter seems to be rather uniformly distributed throughout the universe. 
B)  Dark matter is concentrated in the centers of galaxies and may, in fact, be related to black holes at galactic centers. 
C)  Dark matter is concentrated in the planes of galaxies but extends far beyond the visible galactic plane. 
D)  Dark matter appears to be concentrated in spherical haloes around galaxies but extends several times the radius of visible matter. 
A)  Dark matter seems to be rather uniformly distributed throughout the universe. 
B)  Dark matter is concentrated in the centers of galaxies and may, in fact, be related to black holes at galactic centers. 
C)  Dark matter is concentrated in the planes of galaxies but extends far beyond the visible galactic plane. 
D)  Dark matter appears to be concentrated in spherical haloes around galaxies but extends several times the radius of visible matter.

Question 19

Dark matter in clusters of galaxies:

Accepted Answer

A)  does not appear to exist. 
B)  is distributed uniformly throughout the volume of a cluster. 
C)  is distributed mostly in and around the galaxies in a cluster, not in the voids between galaxies. 
D)  is distributed mostly in the voids between galaxies, not within the galaxies themselves. 
A)  does not appear to exist. 
B)  is distributed uniformly throughout the volume of a cluster. 
C)  is distributed mostly in and around the galaxies in a cluster, not in the voids between galaxies. 
D)  is distributed mostly in the voids between galaxies, not within the galaxies themselves.

Question 20

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. 
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.

Cygnus A,a strong radio source,is also designated 3C 405.What does the "3C" stand for?

The MOST important reason globular clusters are useful for finding the speed of the Sun in its orbit around the Milky Way is that:

What mechanism is believed to produce flocculent spiral galaxies?

In a spiral galaxy,the:

The high redshifts seen for quasars could also be interpreted as nearby objects with high Doppler shifts caused by rapid motion.Why has this interpretation generally been rejected?

The present estimate for the total mass of the Milky Way Galaxy in units of solar mass is about:

Which parameter representing the motion of the material in the spiral arm of a galaxy is approximately constant and should lead to spiral structure in a galaxy?

An astronomer studying a distant cluster of galaxies finds that several of the galaxies are spiral-shaped,with a nuclear region of moderate size and moderately wound arms.How should the astronomer classify these galaxies?

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

What is a rich cluster of galaxies?

Among any number of questions about our Galaxy,which is one for which we have an answer at the present time?

Who first showed that the recessional speeds of galaxies increase with increasing distance from Earth?

One of the recently discovered components of clusters of galaxies that may have some bearing on the dark matter problem is:

In which direction(s)is/are the jets of matter ejected from a supermassive black hole to produce the many effects surrounding quasars and active galaxies?

A moving electron in a magnetic field in space follows a spiral pattern,emitting what type of radiation as it does so?

Which parameter is plotted as a function of distance from the galactic center in a rotation curve of a galaxy?

In order to measure the speed of the Sun with respect to the center of the galaxy,it was necessary to establish a rest frame.What was used to establish this frame?

As much as 90% of the matter in the universe may be unseen "dark matter." Where is this dark matter?

Dark matter in clusters of galaxies:

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:

Discovering the Night Sky

Gravitation and the Waltz of the Planets

Light and Telescopes

Formation of the Solar System and Other Planetary Systems

Exoplanets

The Terrestrial Planets and Their Moons

The Outer Planets and Their Moons

Vagabonds of the Solar System

The Sun: Our Extraordinary Ordinary Star

Characterizing Stars

The Lives of the Stars From Birth Through Middle Age

The Deaths and Remnants of Stars

Cosmology

Astrobiology

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Exam 13: The Galaxies

Cygnus A,a strong radio source,is also designated 3C 405.What does the "3C" stand for?

The MOST important reason globular clusters are useful for finding the speed of the Sun in its orbit around the Milky Way is that:

What mechanism is believed to produce flocculent spiral galaxies?

In a spiral galaxy,the:

The high redshifts seen for quasars could also be interpreted as nearby objects with high Doppler shifts caused by rapid motion.Why has this interpretation generally been rejected?

The present estimate for the total mass of the Milky Way Galaxy in units of solar mass is about:

Which parameter representing the motion of the material in the spiral arm of a galaxy is approximately constant and should lead to spiral structure in a galaxy?

An astronomer studying a distant cluster of galaxies finds that several of the galaxies are spiral-shaped,with a nuclear region of moderate size and moderately wound arms.How should the astronomer classify these galaxies?

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

What is a rich cluster of galaxies?

Among any number of questions about our Galaxy,which is one for which we have an answer at the present time?

Who first showed that the recessional speeds of galaxies increase with increasing distance from Earth?

One of the recently discovered components of clusters of galaxies that may have some bearing on the dark matter problem is:

In which direction(s)is/are the jets of matter ejected from a supermassive black hole to produce the many effects surrounding quasars and active galaxies?

A moving electron in a magnetic field in space follows a spiral pattern,emitting what type of radiation as it does so?

Which parameter is plotted as a function of distance from the galactic center in a rotation curve of a galaxy?

In order to measure the speed of the Sun with respect to the center of the galaxy,it was necessary to establish a rest frame.What was used to establish this frame?

As much as 90% of the matter in the universe may be unseen "dark matter." Where is this dark matter?

Dark matter in clusters of galaxies:

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:

Discovering the Night Sky

Gravitation and the Waltz of the Planets

Light and Telescopes

Formation of the Solar System and Other Planetary Systems

Exoplanets

The Terrestrial Planets and Their Moons

The Outer Planets and Their Moons

Vagabonds of the Solar System

The Sun: Our Extraordinary Ordinary Star

Characterizing Stars

The Lives of the Stars From Birth Through Middle Age

The Deaths and Remnants of Stars

Cosmology

Astrobiology

Filters