Question 1

The presence of a very large amount of unseen matter ("dark matter")in the halo of the Milky Way Galaxy is deduced from:

Accepted Answer

A)  the rotation curve of the Galaxy, in which orbital speeds of stars appear to obey Kepler's law. 
B)  the rotation curve of the Galaxy, in which orbital speeds of stars in the outer regions of the Galaxy are significantly higher than is predicted by Kepler's law in which the value for the observed mass in the Galaxy is used. 
C)  the unexpected absence of luminous matter (stars, and so on) beyond a certain distance from the galactic center. 
D)  the high amount of interstellar absorption in certain directions. 
A)  the rotation curve of the Galaxy, in which orbital speeds of stars appear to obey Kepler's law. 
B)  the rotation curve of the Galaxy, in which orbital speeds of stars in the outer regions of the Galaxy are significantly higher than is predicted by Kepler's law in which the value for the observed mass in the Galaxy is used. 
C)  the unexpected absence of luminous matter (stars, and so on) beyond a certain distance from the galactic center. 
D)  the high amount of interstellar absorption in certain directions.

Question 2

In which constellation in Earth's sky is the center of the Milky Way Galaxy located?

Accepted Answer

A)  Sagittarius 
B)  Lyra 
C)  Hercules 
D)  Ursa Major 
A)  Sagittarius 
B)  Lyra 
C)  Hercules 
D)  Ursa Major

Question 3

The dimensions of the disk of the Milky Way Galaxy are diameter _____,thickness _____.

Accepted Answer

A)  100,000 ly; 2000 ly 
B)  10,000 ly; 28,000 ly 
C)  2000 ly; 100,000 ly 
D)  28,000 ly; 2000 ly 
A)  100,000 ly; 2000 ly 
B)  10,000 ly; 28,000 ly 
C)  2000 ly; 100,000 ly 
D)  28,000 ly; 2000 ly

Question 4

A rotation curve is a plot of the rotational velocity of a galaxy as a function of the distance away from the galactic center.Predictions for rotation curves for spiral galaxies suggest that the curve should decline beyond the galactic bulge.Actual measurements,however,show that the rotation curve is flat beyond the bulge.What does this deviation from prediction tell us about spiral galaxies,including the Milky Way?

Accepted Answer

A)  Spiral galaxies are not rotating as rapidly as we had believed. 
B)  The spiral arms move together as a rigid object. 
C)  There is a great deal of unseen mass surrounding the visible galaxy. 
D)  The centers of spiral galaxies contain supermassive black holes. 
A)  Spiral galaxies are not rotating as rapidly as we had believed. 
B)  The spiral arms move together as a rigid object. 
C)  There is a great deal of unseen mass surrounding the visible galaxy. 
D)  The centers of spiral galaxies contain supermassive black holes.

Question 5

In observations of a double-quasar image produced by gravitational lensing,fluctuations on the intensity of one image appear to be delayed compared with equivalent variations on the other image.Explain.

Accepted Answer

A)  Rotation of the lensing galaxy has delayed the beam of light on one side compared with the other because of the Doppler effect. 
B)  One beam has had to pass through material with a greater refractive index than for the other beam within the lensing galaxy. 
C)  The gravitational field of the lensing object slows down the light on one beam compared with the other. 
D)  The optical path through the gravitational lens producing one image is longer than that for the other image. 
A)  Rotation of the lensing galaxy has delayed the beam of light on one side compared with the other because of the Doppler effect. 
B)  One beam has had to pass through material with a greater refractive index than for the other beam within the lensing galaxy. 
C)  The gravitational field of the lensing object slows down the light on one beam compared with the other. 
D)  The optical path through the gravitational lens producing one image is longer than that for the other image.

Question 6

The Local Group is:

Accepted Answer

A)  the name of the spiral arm of the Milky Way Galaxy in which the Sun is located. 
B)  a cluster of galaxies in which the Milky Way is located. 
C)  the family of planets around the Sun. 
D)  a star cluster to which the Sun belongs. 
A)  the name of the spiral arm of the Milky Way Galaxy in which the Sun is located. 
B)  a cluster of galaxies in which the Milky Way is located. 
C)  the family of planets around the Sun. 
D)  a star cluster to which the Sun belongs.

Question 7

Which property is NOT typical of elliptical galaxies?

Accepted Answer

A)  old Population II stars 
B)  supernova remnants 
C)  neutron stars 
D)  dark nebulae 
A)  old Population II stars 
B)  supernova remnants 
C)  neutron stars 
D)  dark nebulae

Question 8

If we aim a radio telescope at a distant spiral arm of the Milky Way Galaxy,we will probably observe a 21-cm line.If we point a large optical telescope at this same region,we will probably not be able to detect the neutral hydrogen that gives rise to the 21-cm radio signal.Why not?

Accepted Answer

A)  Neutral hydrogen is incapable of emitting visible radiation. 
B)  The Hα line-the primary emission of neutral hydrogen-has a much smaller energy than the 21-cm radio wave and thus is harder to detect. 
C)  There is little energy in the depths of space to excite visible radiation from neutral hydrogen. 
D)  The visible light emitted by neutral hydrogen is all absorbed by H II gas regions before reaching the solar system. 
A)  Neutral hydrogen is incapable of emitting visible radiation. 
B)  The Hα line-the primary emission of neutral hydrogen-has a much smaller energy than the 21-cm radio wave and thus is harder to detect. 
C)  There is little energy in the depths of space to excite visible radiation from neutral hydrogen. 
D)  The visible light emitted by neutral hydrogen is all absorbed by H II gas regions before reaching the solar system.

Question 9

The Milky Way Galaxy:

Accepted Answer

A)  is one of many billions of galaxies in the universe. 
B)  is unique in the universe in showing definite spiral structure. 
C)  contains the whole universe; everything observable is within its volume. 
D)  is one of only a few spiral galaxies; most other galaxies in the universe are amorphous collections of stars shaped like ellipsoids. 
A)  is one of many billions of galaxies in the universe. 
B)  is unique in the universe in showing definite spiral structure. 
C)  contains the whole universe; everything observable is within its volume. 
D)  is one of only a few spiral galaxies; most other galaxies in the universe are amorphous collections of stars shaped like ellipsoids.

Question 10

Compared with the Milky Way Galaxy,a giant elliptical like M86 has:

Accepted Answer

A)  more gas and dust. 
B)  a higher rate of star formation. 
C)  more stars. 
D)  spiral arms that are more loosely wound. 
A)  more gas and dust. 
B)  a higher rate of star formation. 
C)  more stars. 
D)  spiral arms that are more loosely wound.

Question 11

If you are trying to locate starburst galaxies,which spectral region would be a good one in which to observe?

Accepted Answer

A)  infrared 
B)  ultraviolet 
C)  X-ray 
D)  gamma-ray 
A)  infrared 
B)  ultraviolet 
C)  X-ray 
D)  gamma-ray

Question 12

What is the brightest "standard candle," and therefore the one that is visible to the greatest distance,found so far?

Accepted Answer

A)  Type Ia supernovae 
B)  brightest H II regions in each galaxy 
C)  brightest globular cluster of each galaxy 
D)  Cepheid variables 
A)  Type Ia supernovae 
B)  brightest H II regions in each galaxy 
C)  brightest globular cluster of each galaxy 
D)  Cepheid variables

Question 13

What was the implication of the observation by Edwin Hubble that the Cepheid variable stars he measured in the Andromeda "nebula" appeared to be very faint compared with what was expected?

Accepted Answer

A)  The observed period was affected by the intense gravitational field of the "nebula" as predicted by general relativity, leading to incorrect luminosity determination. 
B)  The Andromeda "nebula" was very far away and was in fact a galaxy. 
C)  Hubble had discovered a new class of intrinsically faint Cepheid variable stars. 
D)  Dust and gas in the "nebula" had severely reduced the light from these stars. 
A)  The observed period was affected by the intense gravitational field of the "nebula" as predicted by general relativity, leading to incorrect luminosity determination. 
B)  The Andromeda "nebula" was very far away and was in fact a galaxy. 
C)  Hubble had discovered a new class of intrinsically faint Cepheid variable stars. 
D)  Dust and gas in the "nebula" had severely reduced the light from these stars.

Question 14

Each of the following is a possible consequence of the interaction of two or more galaxies EXCEPT ONE.Which is the exception?

Accepted Answer

A)  Change of galaxy type-for example, two disk galaxies might merge to form an elliptical. 
B)  Globular clusters can form. 
C)  The black holes in one or more galaxies dissipate and enhance the intergalactic medium. 
D)  The intergalactic medium can be enhanced. 
A)  Change of galaxy type-for example, two disk galaxies might merge to form an elliptical. 
B)  Globular clusters can form. 
C)  The black holes in one or more galaxies dissipate and enhance the intergalactic medium. 
D)  The intergalactic medium can be enhanced.

Question 15

What is the Hubble classification for a spiral galaxy with a moderately sized nuclear region and moderately wound arms?

Accepted Answer

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

Question 16

The luminosity of the Milky Way Galaxy is about ten billion times the luminosity of the Sun.During peak periods of brightness,the quasar 3C 279 has a luminosity about ten thousand times the luminosity of our Galaxy.Suppose the flux (energy per second per emitting area)from our Sun remains the same,but it grows in radius.How big would it have to be to produce the same luminosity as 3C 273 at its peak?

Accepted Answer

A)  about the size of Pluto's orbit 
B)  about a hundred times the diameter of Pluto's orbit 
C)  about a light year across 
D)  about one-tenth the diameter of the Galaxy 
A)  about the size of Pluto's orbit 
B)  about a hundred times the diameter of Pluto's orbit 
C)  about a light year across 
D)  about one-tenth the diameter of the Galaxy

Question 17

The broadening of spectral lines due to the collective Doppler shifts of objects orbiting the center of the Milky Way Galaxy suggests that the mass at the center of the Galaxy is about 4 million solar masses.What is believed to be the diameter of this supermassive object?

Accepted Answer

A)  about half a parsec 
B)  about 8 ly 
C)  about the diameter of the solar system 
D)  smaller than the diameter of the Sun 
A)  about half a parsec 
B)  about 8 ly 
C)  about the diameter of the solar system 
D)  smaller than the diameter of the Sun

Question 18

How do MOST spiral galaxies rotate?

Accepted Answer

A)  The arms lead as the galaxy rotates (the arms point forward). 
B)  Spiral galaxies do not rotate; if they did, the spiral pattern would soon disappear. 
C)  We do not know; spiral galaxies rotate far too slowly for us to have seen any motion in the time since galaxies were discovered. 
D)  The arms trail as the galaxy rotates (the arms point backward). 
A)  The arms lead as the galaxy rotates (the arms point forward). 
B)  Spiral galaxies do not rotate; if they did, the spiral pattern would soon disappear. 
C)  We do not know; spiral galaxies rotate far too slowly for us to have seen any motion in the time since galaxies were discovered. 
D)  The arms trail as the galaxy rotates (the arms point backward).

Question 19

Which arrangement is CORRECLTY listed in order of increasing size?

Accepted Answer

A)  ultra compact dwarfs, globular clusters, spiral galaxies 
B)  globular clusters, ultra compact dwarfs, spiral galaxies 
C)  globular clusters, spiral galaxies, ultra compact dwarfs 
D)  ultra compact dwarfs, spiral galaxies, globular clusters 
A)  ultra compact dwarfs, globular clusters, spiral galaxies 
B)  globular clusters, ultra compact dwarfs, spiral galaxies 
C)  globular clusters, spiral galaxies, ultra compact dwarfs 
D)  ultra compact dwarfs, spiral galaxies, globular clusters

Question 20

Harlow Shapley first located the center of the Milky Way Galaxy in 1917 by:

Accepted Answer

A)  measuring the positions of supernova explosions throughout the Galaxy. 
B)  observing the distribution of globular clusters in the galactic halo. 
C)  measuring redshifts of stars in the galactic plane and disk. 
D)  observing the distribution of hydrogen gas, measured by 21-cm radio emission. 
A)  measuring the positions of supernova explosions throughout the Galaxy. 
B)  observing the distribution of globular clusters in the galactic halo. 
C)  measuring redshifts of stars in the galactic plane and disk. 
D)  observing the distribution of hydrogen gas, measured by 21-cm radio emission.

The presence of a very large amount of unseen matter ("dark matter")in the halo of the Milky Way Galaxy is deduced from:

In which constellation in Earth's sky is the center of the Milky Way Galaxy located?

The dimensions of the disk of the Milky Way Galaxy are diameter _,thickness _.

In observations of a double-quasar image produced by gravitational lensing,fluctuations on the intensity of one image appear to be delayed compared with equivalent variations on the other image.Explain.

The Local Group is:

Which property is NOT typical of elliptical galaxies?

If we aim a radio telescope at a distant spiral arm of the Milky Way Galaxy,we will probably observe a 21-cm line.If we point a large optical telescope at this same region,we will probably not be able to detect the neutral hydrogen that gives rise to the 21-cm radio signal.Why not?

The Milky Way Galaxy:

Compared with the Milky Way Galaxy,a giant elliptical like M86 has:

If you are trying to locate starburst galaxies,which spectral region would be a good one in which to observe?

What is the brightest "standard candle," and therefore the one that is visible to the greatest distance,found so far?

What was the implication of the observation by Edwin Hubble that the Cepheid variable stars he measured in the Andromeda "nebula" appeared to be very faint compared with what was expected?

Each of the following is a possible consequence of the interaction of two or more galaxies EXCEPT ONE.Which is the exception?

What is the Hubble classification for a spiral galaxy with a moderately sized nuclear region and moderately wound arms?

The broadening of spectral lines due to the collective Doppler shifts of objects orbiting the center of the Milky Way Galaxy suggests that the mass at the center of the Galaxy is about 4 million solar masses.What is believed to be the diameter of this supermassive object?

How do MOST spiral galaxies rotate?

Which arrangement is CORRECLTY listed in order of increasing size?

Harlow Shapley first located the center of the Milky Way Galaxy in 1917 by:

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

Exam 13: The Galaxies

The presence of a very large amount of unseen matter ("dark matter")in the halo of the Milky Way Galaxy is deduced from:

In which constellation in Earth's sky is the center of the Milky Way Galaxy located?

The dimensions of the disk of the Milky Way Galaxy are diameter _____,thickness _____.

In observations of a double-quasar image produced by gravitational lensing,fluctuations on the intensity of one image appear to be delayed compared with equivalent variations on the other image.Explain.

The Local Group is:

Which property is NOT typical of elliptical galaxies?

If we aim a radio telescope at a distant spiral arm of the Milky Way Galaxy,we will probably observe a 21-cm line.If we point a large optical telescope at this same region,we will probably not be able to detect the neutral hydrogen that gives rise to the 21-cm radio signal.Why not?

The Milky Way Galaxy:

Compared with the Milky Way Galaxy,a giant elliptical like M86 has:

If you are trying to locate starburst galaxies,which spectral region would be a good one in which to observe?

What is the brightest "standard candle," and therefore the one that is visible to the greatest distance,found so far?

What was the implication of the observation by Edwin Hubble that the Cepheid variable stars he measured in the Andromeda "nebula" appeared to be very faint compared with what was expected?

Each of the following is a possible consequence of the interaction of two or more galaxies EXCEPT ONE.Which is the exception?

What is the Hubble classification for a spiral galaxy with a moderately sized nuclear region and moderately wound arms?

The broadening of spectral lines due to the collective Doppler shifts of objects orbiting the center of the Milky Way Galaxy suggests that the mass at the center of the Galaxy is about 4 million solar masses.What is believed to be the diameter of this supermassive object?

How do MOST spiral galaxies rotate?

Which arrangement is CORRECLTY listed in order of increasing size?

Harlow Shapley first located the center of the Milky Way Galaxy in 1917 by:

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

The dimensions of the disk of the Milky Way Galaxy are diameter _,thickness _.