PHY 110: Astronomy and Cosmology:
Stars and Galaxies
Fall
2008
Prof. Matilsky's Website • Astronomy at Rutgers • Department of Physics & Astronomy • Rutgers University
Last updated October 5, 2006
Practice
Final
Note that this exam was based on a different
textbook that the one being used this semester, so the emphasis on material may
have been slightly different than in our course. Furthermore, unlike your
final, this exam is NOT cumulative. See the practice mid-term for material from
the first part of the course.
Click here for the solutions.
1. The globular clusters in our Galaxy
are roughly spherically distributed around:
a. the Sun
b. a point that is about 8.5 kpc from us in the direction of Sagittarius
c. a point that is about 8.5 kpc from us in the direction of Orion
d. a black hole, 2 kpc away from the Sun
e. a nearby spiral arm
2. O-type and B-type stars in our Galaxy are
usually located in:
a. the halo of the Galaxy
b. the bulge of the Galaxy
c. the spiral arms of the Galaxy
d. the globular clusters of the Galaxy
e. uniformly distributed throughout the Galaxy
3. Which term does not belong with the others?
a. bulge
b. disk
c. halo
d. spiral arm
e. supernova
4. What is the classification of our Galaxy (the
Milky Way)?
a. Spiral
b. Elliptical
c. Lenticular (S0)
d. Irregular Type I
e. Irregular Type II
5. The rotation curve of our Galaxy at large
distances from the center is constant (flat), indicating that:
a. Our Galaxy is a spiral galaxy.
b. Our Galaxy has a great deal of dark matter.
c. The material in our Galaxy is mostly concentrated in its center.
d. Our Galaxy has a massive black hole in the center that accounts for 99%
of its mass.
e. The material in our Galaxy is uniformly distributed between its center
and its edge.
6. A galaxy that has very little gas and dust,
stars of low mass and temperature, no rotation, and circular shape is a(n):
a. E0 galaxy
b. E7 galaxy
c. S0 galaxy
d. SBa galaxy
e. Sa galaxy
7. When two galaxies collide:
a. They destroy each other's stars.
b. They pass through each other without any effects to either galaxy.
c. They distort each other's shapes by gravitational tidal interactions.
d. They merge into a giant black hole.
e. Actually, galaxy collisions never happen, since galaxies are so far apart
and moving so slowly.
8. How do astronomers measure the total mass of
an elliptical galaxy?
a. By measuring the rotation curve of the galaxy, from which
its mass can be determined.
b. By measuring the velocity dispersion as a function of radius for the
galaxy, from which its total mass can be determined.
c. By measuring the orbital velocities of molecular clouds outside of the
galaxy.
d. By measuring the neutrino flux from the galaxy.
e. By measuring the size of the galaxy and applying the size-mass
relationship for elliptical galaxies.
9. Which of the following techniques is used by
astronomers to discover dark matter in the form of cool white dwarfs, brown
dwarfs, or neutron stars in the halo of the Milky Way?
a. looking for dark spots against the stellar background
b. looking for pulsating radio sources
c. looking for pulsating sources of gravitational waves
d. looking for regions where the stars have much higher heavy element
abundance than average
e. looking for stellar brightening by gravitational lensing
10. Which observation suggests that the Milky
Way is a disk galaxy?
a. The stars of the Milky Way have about 2% heavy element
abundance.
b. Astronomers have detected a million solar mass black hole in the center
of the Milky Way.
c. The light of Milky Way appears as a luminous band stretching across the
sky.
d. There are hundreds of globular clusters containing old, metal-poor stars
in the Milky Way.
e. Every known alien civilization in the Milky Way has invented the Frisbee.
11. What is the best method to measure the
distance to the Fornax galaxy, a small dwarf spheroidal (i.e. a very small
elliptical) galaxy in the Local Group that is sufficiently close to us so that
its individual stars can be resolved?
a. laser ranging
b. geometrical parallax
c. Cepheid variable stars
d. the Tully-Fisher relation
e. the Hubble Law
12. Why has the determination of H0 been an
important goal of 20th century observational astronomy?
a. Because the value of H0 provides an estimate on the
number of quasars in the universe.
b. Because the value of H0 provides an estimate of the density of elements
heavier than helium in the universe.
c. Because the value of H0 provides an estimate of the total number of
galaxies in the universe.
d. Because the value of H0 provides an estimate of both the age of the
universe and the distance of very distant galaxies.
e. Because the determination of the value of H0 provides employment for a
large number of observational astronomers.
13. According to Hubble's Law,
a. the more distant a galaxy is, the greater its peculiar
velocity is.
b. the more distant a galaxy is, the greater its luminosity is.
c. the more distant a galaxy is, the greater its diameter is.
d. the more distant a galaxy is, the greater its recessional (expansion)
velocity is.
e. the more distant a galaxy is, the dimmer it is.
14. If we observe some other galaxy receding
from us at half the speed of light, what would astronomers in that galaxy
observe?
a. Our galaxy (only) approaching them at half the speed of
light.
b. All other galaxies approaching them at half the speed of light.
c. All galaxies on our side of the universe approaching them, and all
galaxies on the other side of the universe receding from them.
d. Our galaxy receding from them at half the speed of light.
e. All galaxies in the universe at rest, except for their own galaxy.
15. The Milky Way is:
a. a member of a group of galaxies containing about 30
galaxies.
b. a member of a cluster of galaxies containing about 3,000 galaxies.
c. located in a large void with the nearest galaxy about 10 Mpc away.
d. not a member of any larger structure of galaxies.
e. Bart Simpson's favorite candy bar.
16. Why is a carbon detonation supernova (type
Ia supernova or white dwarf supernova) a good standard candle?
a. Because, after correction for the luminosity-light curve
shape effect, type Ia supernovae have well-determined luminosities and can be
seen to very large distances.
b. Because the color of the light emitted by a type Ia supernova depends on
its distance from us.
c. Because the spectral features due to carbon are very prominent compared
to those due to hydrogen in a type Ia supernova.
d. Because the rotational velocity of the type Ia supernova remnant is
proportional to the mass of the remnant which, in turn, is proportional to its
intrinsic luminosity.
e. Because Type Ia supernova are the premium product of the candle-makers
union, and each one comes with a certificate of authenticity.
17. Which of the following statements about
clusters of galaxies is false?
a. Elliptical galaxies tend to outnumber spiral galaxies in
the central region of a typical rich galaxy cluster.
b. The cD (central dominant) galaxies found in many rich clusters are
several times larger and brighter than normal galaxies.
c. Clusters of galaxies themselves cluster into larger systems known as
superclusters.
d. Hot gas occupies the intergalactic space in a typical rich galaxy cluster
and the properties of the gas imply that the cluster contains dark matter.
e. A cluster of galaxies forms when two large galaxies collide and shatter
into many smaller galaxies that remain gravitational bound to each other.
18. The unified model for active galaxies
(quasars, radio galaxies, Seyfert galaxies, and BL Lac objects) is based on:
a. Annihilation between matter and anti-matter in the
central regions of these galaxies. The type of active galaxy observed depends
on the kinds of particles that annihilate.
b. Mini Big Bangs occurring in the central regions of these galaxies. The
type of active galaxy observed depends on the average mass density of these
explosions.
c. A chain-reaction of supernova explosions in the central regions of these
galaxies. The type of active galaxy observed depends on the number of supernova
explosions.
d. Gravitational collapse of a massive molecular cloud in the central
regions of these galaxies. The type of active galaxy observed depends on the
chemical composition of the cloud.
e. Accretion of matter by a massive black hole in the central regions of
these galaxies. The type of active galaxy observed depends on the viewing
position of the observer.
19. The quicker the variations of a quasar's
brightness are, the ______ the quasar must be.
a. brighter
b. smaller
c. closer
d. fainter
e. more distant
20. Which statement about quasars is false?
a. The brightness of a typical quasar is much greater than
the brightness of an average galaxy.
b. Some quasars are bright radio sources.
c. The spectrum of some quasars contains absorption features produced by
intergalactic material.
d. Quasars are just as common now as they were billions of years ago.
e. Astronomers have not discovered a quasar with a blueshift.
21. The radio emission from radio galaxies most
often comes from:
a. the spiral arms of the galaxy
b. Population I stars within the galaxy
c. regions of active star formation
d. central jets and/or outer low-density lobes
e. alien top-40 stations
22. Astronomers have discovered multiple images
of the same quasar close together in the sky. Such multiple images form when:
a. The light from the quasar reflects off dark halos of
massive galaxies.
b. The recessional (expansion) velocity of the quasar exceeds the speed of
light.
c. One large quasar disintegrates into several smaller quasars.
d. The light from the quasar is bent by gravity of a galaxy or cluster of
galaxies.
e. The light from the quasar has enough time to circle the universe multiple
times.
23. The Cosmological Principle states that:
a. On sufficiently long time scales, the universe does not
change its characteristics.
b. On sufficiently large spatial scales, the universe is homogeneous and
isotropic.
c. The universe will expand forever.
d. The universe began in an explosive event of extreme temperature and
density.
e. The universe consists of a four-dimensional space-time continuum.
24. Hubble's Law implies that:
a. There must be a serious flaw in our measurements of
distances, since we seem to be at the center of the expansion of the universe,
and there is no reason that we should occupy such a special position.
b. In the past the universe was much hotter and denser, and has been
expanding and cooling ever since.
c. The universe is static and unchanging. Thus Einstein's original
formulation of general relativity was incorrect, and required the introduction
of the cosmological constant, which Einstein viewed as his greatest
achievement.
d. Our understanding of the nature of gravity must be incomplete, since a
repulsive gravitational force is required to make the universe expand against
the gravitational attraction of normal matter.
e. The most distant galaxies must be moving through space at speeds
exceeding the speed of light, which is in serious contradiction to the
predictions of relativity.
25. What is meant by the term critical density
in a cosmological context?
a. the minimum density needed to allow galaxies to form
b. the minimum density needed to allow stars to form
c. the minimum density needed to stop the expansion of the universe
d. the minimum density needed to create hydrogen in the early universe
e. the maximum density at which all four forces of nature appear separate
and distinct
26. In the early universe, what happens when a
particle annihilates with its anti-particle?
a. Radiation is produced.
b. Dark matter is produced.
c. A helium nucleus is produced.
d. A black hole is produced.
e. The rate of expansion of the universe increases.
27. Which observation provided the conclusive
support for the Big Bang theory of cosmology?
a. the discovery of Cepheid variables
b. the discovery of clusters of galaxies
c. the discovery of the cosmic microwave background radiation
d. the discovery of quasars
e. the discovery of gravitational lenses
28. How would you characterize the universe
300,000 years after the Big Bang?
a. The universe was cool enough for gravity to begin to form
large-scale structures.
b. The universe was hot and dense enough for nuclear reactions to occur
everywhere.
c. The universe had only two fundamental forces: gravity and the grand
unified force.
d. The universe was so hot that not even protons, neutrons, or electrons
could exist.
e. The universe is accurately characterized at this stage by Mel Brooks'
300,000 year old man.
29. What happened when the universe was about 3
minutes old?
a. The strong nuclear force and the weak nuclear force
decoupled from each other.
b. The helium content of the universe was produced.
c. The Universe became transparent.
d. Galaxies and clusters began to form.
e. We don't know - this is one of the unsolved mysteries in modern
cosmology.
30. The shape of the spectrum of the microwave
background radiation is most like that of:
a. synchrotron radiation
b. an HII region
c. a quasar
d. a fluorescent lamp containing a hot, low-density gas
e. an incandescent lamp with a hot wire filament
31. Which of the following is a way to determine
observationally whether the universe is open or closed?
a. measuring the distance from the Sun to the center of the
Milky Way
b. measuring the abundance of anti-matter in the Milky Way galaxy
c. measuring the expansion rate of the universe today and at an earlier
epoch
d. measuring the frequency of occurrence of intelligent civilizations in the
universe
e. measuring precisely the temperature of the microwave background radiation
32. Imagine that astronomers discover that the
universe is contracting. Within the standard cosmological model, such a
universe is
a. open
b. flat
c. closed
d. empty
e. infinite in space and time
33. In inflationary cosmology, when does
inflation occur?
a. periodically, starting from the time of the Big Bang to
the present time
b. continuously, starting from the time of the Big Bang to the present time
c. at the time of recombination
d. within the first second after the Big Bang
e. whenever the Republicans control the House, the Senate, and the White
House
34. What do astronomers mean by the flatness
problem?
a. The cosmological density parameter Omega is very close to
1, i.e. the density of the universe is very close to the critical density.
b. The cosmological density parameter Omega is very close to 0, i.e. the
universe is very nearly empty.
c. The flatness of an elliptical galaxy increases with increasing distance.
d. The plot of recessional (expansion) velocity versus distance approaches
an almost horizontal line at large distances.
e. An open bottle of Club Soda in the refrigerator quickly goes flat.
35. What is Olber's Paradox?
a. Why is the sky black at night?
b. Why is the sky blue during the day?
c. Why is the sky red at sunset or sunrise?
d. Why is there oxygen even though none was produced during the Big Bang?
e. Why is there matter but no anti-matter on Earth?
36. What is the resolution to Olber's Paradox?
a. The dust in the universe causes reddening and extinction.
b. Inflation.
c. The universe is infinite in extent.
d. The universe has a finite age.
e. We don't know - this is one of the unsolved mysteries in modern
cosmology.
37. What recent observation prompted astronomers
to resurrect the idea of the cosmological constant?
a. The universe was static until about 10 billion years ago.
b. The rate of the expansion of the universe seems to be constant, i.e. independent
of time.
c. The rate of expansion of the universe seems to decrease as time goes on.
d. The rate of expansion of the universe seems to increase as time goes on.
e. The size of the universe oscillates around some average value.
38. Which of the following is not a likely
condition for life to form in the universe?
a. a liquid environment
b. a steady source of energy
c. a planetary surface
d. moderate temperatures
e. location near the center of a galaxy
39. Which systems should astronomers searching for
intelligent life choose to study in order to maximize their chances of success?
a. giant molecular clouds
b. planets orbiting about pulsars
c. planets orbiting about O-type stars
d. planets orbiting about Sun-like stars
e. the other planets of our solar system
40. What is the best way to detect an
intelligent alien civilization?
a. Build spaceships and travel to nearby stars.
b. Send robot probes to all planets in the solar system.
c. Perform optical wavelength searches for pulsed signals.
d. Listen at radio wavelengths for deliberate messages.
e. Investigate all UFO reports fully.
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