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Dark matter is matter that gives out no observable radiation and is detected by its gravitational interaction alone. Which of these does NOT provide direct evidence for dark matter?


A) separation of visible and dark matter in collisions of galaxy clusters
B) emission from hot intergalactic gas in galaxy clusters
C) gravitational lensing by unseen objects
D) insufficient visible mass to bind galaxy clusters gravitationally

E) B) and C)
F) None of the above

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What are the Magellanic Clouds?


A) Type I irregular galaxies near the Milky Way Galaxy
B) Type II irregular galaxies near the Milky Way Galaxy
C) globular clusters in the halo of the Milky Way Galaxy
D) very large clouds of gas and dust that are part of the outer halo of the Milky Way Galaxy

E) A) and B)
F) A) and C)

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A spiral galaxy is observed edge-on so that the spiral arms cannot be seen clearly. Is it possible to classify this into one of the Sa, Sb, and Sc categories?


A) Yes. The classification scheme is also an evolutionary scheme. It is possible to classify galaxies by age, for example, by counting the number of blue supergiants visible along the edge.
B) Yes. The tightness of spiral arms is correlated with the size of the nuclear bulge.
C) Yes. The tightness of spiral arms is correlated with the number of bright H II regions that can be counted along the edge.
D) No. The classification scheme is based on the tightness of spiral arms. If the arms cannot be seen, the galaxy cannot be classified.

E) B) and C)
F) All of the above

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Which of these are NOT typically gravitationally bound?


A) open star clusters and superclusters of galaxies
B) globular clusters and superclusters of galaxies
C) galaxy clusters and superclusters
D) globular clusters and galaxy clusters

E) A) and C)
F) C) and D)

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Spiral galaxies are classified in terms of increasing tightness of their spiral arms as types Sa, Sb, and Sc. However, many spiral galaxies are aligned edge-on to Earth and their spiral arms cannot be seen. Which other parameter that is directly related to spiral-arm tightness can be easily seen edge-on and can therefore be used to provide this classification?


A) overall spectral color
B) overall intrinsic brightness of the galaxy, or its absolute magnitude
C) size of the nuclear bulge
D) overall diameter of the galaxy

E) C) and D)
F) A) and D)

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What is an E3 galaxy?


A) galaxy with a smooth light distribution and a moderately elongated elliptical shape without a disk or central bulge
B) galaxy with a smooth light distribution and a very elongated elliptical shape without a disk or central bulge
C) galaxy with a smooth light distribution and a moderately elliptical shape, having a pronounced disk and central bulge
D) galaxy with an irregular light distribution and a very elongated shape

E) C) and D)
F) All of the above

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The method of stellar parallax


A) can be used to measure the distance to stars in distant galaxies just as it can be used for stars in the Milky Way Galaxy.
B) can be used for distant galaxies but only when used with giant molecular clouds (which can be seen at such distances) , not with stars.
C) cannot be used for distant galaxies because redshift spectra are inherently imprecise at such distances.
D) cannot be used for distant galaxies because of the difficulty of resolving the spectra of individual stars.

E) A) and B)
F) All of the above

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What is the designation given to a galaxy with a large nuclear bulge and tightly wound arms starting from a bar through the nuclear bulge?


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

E) A) and B)
F) A) and C)

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Which class of galaxies has the greatest range of sizes in the universe?


A) irregular galaxies
B) ellipticals
C) lenticular galaxies
D) spirals

E) All of the above
F) A) and D)

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Gravitational lensing of distant objects by closer galaxies indicates that the


A) amount of visible matter in the galaxies accounts for only 10% of the total mass producing the lensing.
B) amount of visible matter in the galaxy is about 10 times too great to account for the observed lensing, leading to the idea of negative gravitation within such large-scale structures.
C) amount of visible matter in the galaxies is sufficient to account for the gravitational lensing.
D) total mass within the galaxies that produces the lensing exceeds the amount of visible matter by a factor of 100.

E) A) and D)
F) None of the above

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What is the Tully-Fisher relation?


A) The more distant the galaxy, the greater is the recessional velocity.
B) The brighter the Cepheid, the longer is the pulsation period.
C) The more distant the galaxy, the fainter it appears.
D) The brighter the galaxy, the wider is the 21-cm radio emission line.

E) B) and C)
F) A) and D)

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By 2016 astronomers were able to observe galaxies about 13.4 billion light-years away. Thus, they were observing these galaxies


A) almost immediately after the Big Bang.
B) a few billion years after the beginning of the universe.
C) at about half their present age.
D) at about 90% of their present age.

E) B) and C)
F) C) and D)

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How do nearly all spiral galaxies rotate?


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) Astronomers do not know; spiral galaxies rotate far too slowly for them to have seen any motion in the time since galaxies were discovered.
D) The arms trail as the galaxy rotates (the arms point backward) .

E) B) and D)
F) All of the above

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Which of these objects are used as standard candles for distance measurement to distant galaxies?


A) globular clusters
B) hot white dwarf stars
C) supernova explosions
D) elliptical galaxies

E) C) and D)
F) None of the above

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What is believed to be the origin of starburst galaxies?


A) Starburst galaxies are slower rotators than other galaxies, so the slower-speed collisions between interstellar clouds produce more star formation.
B) Starburst galaxies are newly formed and are undergoing their initial, rapid star formation.
C) A recent collision with another galaxy has triggered a wave of star formation.
D) A recent series of supernovae has compressed the interstellar medium and started a wave of star formation.

E) A) and D)
F) None of the above

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Which one of these properties is NOT typical of elliptical galaxies?


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

E) A) and C)
F) A) and D)

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One of the big puzzles about the properties and behavior of large clusters of galaxies is that


A) each cluster appears to consist of the same type of galaxy, some made up totally of spiral galaxies while others contain only ellipticals.
B) they appear to be spread uniformly throughout space in all directions, which is difficult to explain with the Big Bang theory.
C) there appears to be insufficient mass in the luminous matter (stars, and so on) to hold the cluster together gravitationally.
D) they appear not to take part in the general expansion of the universe, in contrast to single separate galaxies, probably because they are gravitationally bound to one another.

E) A) and B)
F) All of the above

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The typical diameter of a spiral galaxy is about


A) 107 ly.
B) 105 ly.
C) 1 ly.
D) 100 ly.

E) None of the above
F) A) and B)

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Suppose a galaxy is 400 million pc from Earth. What is the recessional velocity of this galaxy? Assume Hubble's constant to be 73.5 km/s per Mpc.


A) 5 km/s
B) 200,000 km/s
C) 29,400 km/s
D) 5 million km/s

E) All of the above
F) A) and D)

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Barred galaxies


A) are increasing in number as the universe ages.
B) are mostly leading-arm spirals.
C) all have tightly wound spiral arms.
D) all have spiral arms wound with various degrees of tightness.

E) None of the above
F) A) and B)

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