1. Star A has an absolute magnitude MA=4.
Star B has an absolute magnitude MB=6. Which one of the following
statements must be true?
2. The parallax angle of star A is
smaller than the parallax angle of star B. Which one of the following
statements must be true?
3. The “OBAFGKM” sequence for stars is
based on:
a.
The
chemical composition of stars.
b.
The
distance to stars.
c.
The
luminosity of stars.
d.
The
density of stars
e.
None of the above
4. Five main sequence stars have the
following spectral types: G4, K8, M6, B4, and A7. Which of these five stars has
the greatest mass?
5. Five main sequence stars have the
following spectral types: M3, K4, G1, A3, and F7. Which of these five stars has
the bluest color?
6. The unit “parsec” is used when
specifying:
a.
Distance to a star
b.
Mass
of a star
c.
Angular
size of a star
d.
Spectral
type of a star
e.
Proper
motion of a star
7. What phenomenon do astronomers rely
on when measuring a line-of-sight (radial) velocity of a star?
a.
Intensification
of spectral features in the star’s spectrum
b.
Shift in wavelength of
spectral features in the star’s spectrum
c.
Narrowing
of spectral features in the star’s spectrum
d.
Broadening
of spectral features in the star’s spectrum
e.
Weakening
of spectral features in the star’s spectrum
8. Which of the following is not a
possible H-R diagram?
9. An atom of hydrogen is in the ground state. This means that:
a.
An
electron in this atom is located in the nucleus.
b.
An
electron in this atom moves on an orbit with the largest allowed radius.
c.
An electron in this
atom moves on an orbit with the smallest allowed radius.
d.
An
electron in this atom is motionless – it does not revolve around the nucleus.
e.
The
atom lost its electron.
10. A hot and low-density gas produces:
a.
Absorption
spectrum
b.
Continuous
spectrum
c.
Emission spectrum
d.
A
superposition of continuous and emission spectra
e.
No
spectrum. Hot gases cannot emit
radiation.
11. Our Sun is the brightest star in our
sky because:
12. What kind of star is our Sun?
13. In the past few decades, astronomers
have invested a great deal of effort and resources on detecting and measuring
the flux of solar neutrinos. What is the
main scientific reason behind this effort?
a.
Neutrinos, produced in
the proton-proton chain, leave the Sun’s interior practically unimpeded and in
only a few seconds - measuring their flux would reveal the current physical
conditions of the Sun’s interior, especially the core.
b.
Neutrinos,
produced in the proton-proton chain, leave the Sun’s interior after hundred of
thousands of years because of scattering with electrons and protons – measuring
their flux would reveal physical conditions of the Sun’s interior, especially
the radiation zone.
c.
Neutrinos,
produced in the proton-proton chain, interact strongly with the magnetic field
of the Sun – measuring the flux of neutrinos reveals information about the
Sun’s magnetic field, which can vary with time.
d.
Measuring
whether the Sun emits neutrinos or not would determine if the thermonuclear
reactions in the Sun’s interior convert hydrogen to helium or helium to carbon.
e.
Measuring
the undulations in the flux of solar neutrinos would be a firm test as to
whether or not the Sun’s interior exhibits mechanical vibrations.
14. Although the Sun can be thought of
as a hot ball of gas, it does not expand significantly over time as would, for
example, a balloon whose gas temperature were increased. Why doesn’t the Sun expand?
a.
The Sun does not
expand because at every point in its interior, the outward force due to gas
pressure is balanced by the inward force of gravity.
b.
The
Sun does not expand because ether in the surrounding space confines it.
c.
The
Sun does not expand because its strong magnetic field confines it.
d.
The
Sun does not expand because at every point in its interior, the outward force
due to gas pressure is bound by a strong nuclear force.
e.
The
Sun does not expand because it is held together by electromagnetic forces
acting between its constituent particles.
15. Thermonuclear reactions in the core
of the Sun produce high energy photons in the form of gamma rays. However, by the time these photons emerge
from the Sun, they are mostly in the form of low-energy, visible light. Why?
a.
As
photons travel from the core to the surface, the gravitational field of the
Sun reduces their energy.
b.
As
photons travel from the core to the surface, the magnetic field of the Sun
reduces their energy.
c.
As photons travel from
the core to the surface, the scattering off of electrons and nuclei reduces
their energy.
d.
As
photons travel from the core to the surface, the scattering amongst themselves
reduces their energy.
e.
As
photons travel from the core to the surface, the high-energy gamma rays
radioactively decay into low-energy photons.
16. How does a sunspot in the
photosphere form?
a.
Convection
in the layer below dredges up cool and dark carbon to the photosphere.
b.
A locally strong
magnetic field below the photosphere impedes convection, thus causing the
surface above it to cool.
c.
A
locally strong gravitational field below the photosphere impedes convection,
and thus causes the surface above it to cool.
d.
A
locally intense flux of neutrinos in the photosphere scatters with photons,
reducing their energy, and thus causing the surface there to cool.
e.
Convection
in the layer below locally dredges up antimatter which annihilates luminous
matter above.
17. Nuclear fusion reactions require
high temperature because:
a.
The
nuclei then move slowly enough that they stick when they collide.
b.
The
nuclei then move slowly enough that they collide frequently.
c.
The
heat energy is converted to mass by E=mc2.
d.
The nuclei then move
quickly enough to overcome their mutual electric repulsion.
e.
The
heated nuclei must melt and merge together.
18. Which statement about star formation
is true?
a.
The
principal force causing a cloud of gas to contract is the electromagnetic force
between the atoms in the cloud.
b.
Star
formation does not occur in our Galaxy because all of the available gas was
used up about 12 billion years ago.
c.
In
a newly formed group of stars, the O- and B-type stars outnumber the K- and
M-type stars.
d.
Emission
nebula is the type of interstellar medium that is most likely to begin forming
stars soon.
e.
A more-massive star
forms faster than a less-massive star.
19. What aspect of star formation from
interstellar medium causes stars to form in clusters?
a.
Formation
of a disk
b.
Conversion
of gravitational potential energy to kinetic energy
c.
Onset
of hydrogen fusion
d.
Rapid
rotation
e.
Fragmentation
20. How does a star's lifetime depend
upon its mass?
a.
The
lifetime of a star is independent of its mass
b.
The
more massive a star, the longer its lifetime
c.
The more massive a
star, the shorter its lifetime
d.
Moderate
mass stars (like the Sun) have longer lifetimes than either high or low mass
stars
e.
Moderate
mass stars (like the Sun) have shorter lifetimes than either high or low mass
star.
21. A star like our Sun leaves the main
sequence when it:
a.
Collapses
to become a white dwarf
b.
Contracts
to become a brown dwarf
c.
Explodes
d.
Exhausts
the hydrogen fuel in its core and starts burning helium in its core
e.
Exhausts the hydrogen
fuel in its core and starts burning hydrogen in a shell around the core
22. The helium flash occurs when:
a.
Helium fusion begins
in a degenerate core.
b.
A
helium white dwarf suddenly collapses.
c.
Helium
fusion begins in a shell around a carbon core.
d.
A
planetary nebula is formed.
e.
A
protostar reaches the main sequence.
23. The location of the turn off point
in an H-R diagram of a globular cluster is affected by:
a.
The
distance to the globular cluster.
b.
The
mass of the globular cluster.
c.
The age of the
globular cluster.
d.
The
size of the globular cluster.
e.
The
number of stars in the globular cluster.
24. If the pressure of a gas does not
change with temperature, then the gas is:
a.
Ideal
b.
Degenerate
c.
Above
1000 degrees Kelvin
d.
Hydrogen
e.
Ionized
25. What type of star does obey the
period-luminosity relationship?
a.
Neutron
star
b.
M5V
c.
Red
dwarf
d.
White
dwarf
e.
None of the above
26. What is Schwarzschild radius?
a.
It
is a radius of a singularity – the innermost part of a black hole.
b.
It is a radius of an
event horizon of a non-rotating black hole.
c.
It
is a radius of a mathematical surface around a black hole where the escape
velocity is half the speed of light.
d.
It
is a radius of a mathematical surface around a black hole where the
gravitational force becomes repulsive.
e.
It
is a radius of a proton.
27. What process could directly lead to
the formation of a neutron star?
a.
Merger
of two black holes
b.
Helium
flash in a red giant
c.
Core-collapse
supernova
d.
Triple
alpha process
e.
Beta
decay of a neutron
28. What is the next phase (after the
main sequence) in the Sun’s evolution?
a.
Planetary
nebula
b.
White
dwarf
c.
Horizontal
branch
d.
Red
supergiant
e.
Red giant
29. What is the last phase in the Sun’s
evolution?
a.
Blue
straggler
b.
Planetary
nebula
c.
Black
hole
d.
White dwarf
e.
Neutron
star
30. When the core of a high mass star is
composed of this element, the star becomes unstable and explodes as a
supernova. What element is it?
a.
Uranium
b.
Iron
c.
Xenon
d.
Silicon
e.
Helium
31. You discover a binary star system in
which one member is a 15 solar-mass main sequence star and the other star is a
10 solar-mass red giant. Why should you
be surprised, at least at first?
32. Suppose a white dwarf is gaining
mass because of accretion in a binary system.
What happens if the mass of the white dwarf reaches the 1.4 solar-mass
limit?
33. Binary star systems allowed
astronomers to determine stellar:
34. Which one of the following
statements about a nova is false?
35. Which of the following terms is
given to a pair of stars that we can determine are orbiting each other only by
measuring their periodic Doppler shifts?
36. What makes up the interstellar medium?
37. What would you find in an HII
region?
38. Which effect does interstellar dust
have on starlight?
39. Imagine you are an astronomer
studying the spatial distribution of globular clusters in our Galaxy. You
discover that most of the globular clusters reside in the:
a.
Halo
b. Nucleus
c. Bulge
d. Disk
e. Spiral arms
40. You are studying the current star
formation in our Galaxy. You plotted the distribution of O-type and B-type
stars in the Galaxy. You discover that these stars are mostly in the:
a. Halo
b. Bulge
c.
Spiral arms
d. Globular clusters of the Galaxy
e. Nucleus
41. Which one of the following
statements about the Sun is false?
a. The Sun is located in the disk of
the Galaxy.
b.
The orbit of the Sun
passes through the Galactic bulge.
c. The Sun is a second (or even third)
generation star characterized by high metallicity.
d. During its lifetime, the Sun has
revolved several times around the Galactic center.
e. The speed of the Sun in its orbit
around the center of the Galaxy is about 220 km/s.
42. After many years of hard work, you
finally constructed the rotation curve of the Milky Way. You discovered that:
a. The rotation curve is the same as
that for a rotating rigid body.
b. The rotation curve has a profile
similar to the one for the planets in the Solar system.
c. The rotation curve implies that the
stellar speeds increase exponentially with the radius.
d. The rotation curve implies that the
stellar speeds decrease exponentially with the radius.
e.
None of the above.
43. What kind of matter seems to
dominate the mass of the Milky Way?
a. Gas and dust
b. Luminous matter in the form of O and
B type stars
c. Luminous matter in the form of K and
M type stars
d. Planets, asteroids, and comets
e.
Dark matter
44. What object is likely to exist at
center of the Milky Way?
45. This type of galaxy contains large
clouds of gas and dust, and both young and old stars, but has no obvious spiral
arms or nucleus. What type of galaxy is
it?
a. Elliptical
b.
Irregular
c. Barred spiral
d. Dwarf elliptical
e. Giant elliptical
46. Which statement about galaxies is
correct?
47. If galaxy A is six (6) times more
distant than galaxy B, then according to Hubble’s Law, galaxy A recedes
__________ galaxy B.
a. 1/6 times faster than
b. 1/36 times faster than
c.
6 times faster than
d. 36 times faster than
e. as fast as
48. What units are commonly used for the
Hubble’s constant?
49. In the above units, the numerical value
of the Hubble’s constant is closest to:
50. One can use the Tully-Fisher
relation to measure:
51. The 21-centimeter line of atomic
hydrogen:
a.
Is our best tool for
mapping the structure and rotation of the Milky Way
b. Is strongly absorbed by dust.
c. Provides the only evidence that the
Sun orbits the center of the Milky Way
d. Is emitted primarily by the hot gas
in the dark halo of the Milky Way
e. Has only been rarely observed by
radio astronomers
52. The most active galactic nuclei are
usually found at large distances from us; relatively few nearby galaxies have
active galactic nuclei. What does this
imply?
a. Massive black holes existed only
when the universe was young and no longer exist today.
b.
Active galactic nuclei
tend to become less active as they age.
c. Active galactic nuclei can form only
at large distances from the Milky Way.
d. The jets seen in many active
galactic nuclei must cause them to move far away from us.
e. Nothing…such distribution of active
nuclei is only by chance.
53. How is the energy that powers radio
galaxies, QSOs, and other active galactic nuclei produced?
a. By nuclear fusion near a central
black hole
b. By magnetic fields that trap and
accelerate charged particles, which then radiate high amounts of energy
c. By chemical reactions between
hydrogen and oxygen near a central black hole
d.
By conversion of
gravitational potential energy of matter falling toward a central black hole
into kinetic energy, which is then converted to thermal energy by collisions
among the particles of matter
e. By matter-antimatter annihilation
near a central black hole
54. What is a quasar?
a. A star-like object that actually
represents a bright patch of gas in the Milky Way.
b. A large galaxy thought to have
formed by mergers of several smaller galaxies, typically found in the center of
a galaxy cluster.
c. Another name for an O-type star
d. A specialized astronomical
instrument for observing distant stars.
e.
An extremely bright
center or nucleus of a distant galaxy.
55. 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
56. Why should galaxy collisions have
been more common in the past than they are today?
a. Galaxies were more active in the
past and therefore would have collided with each other more frequently.
b. Galaxies were much bigger in the
past since they had not contracted completely.
c.
Galaxies were closer
together in the past.
d. Galaxies attracted each other more strongly
in the past because they were more massive; they had not yet turned most of
their mass into stars and light.
e. Galaxy collisions should not have
been more common in the past than they are now.
57. If an object doubles its luminosity
in 10 hours, how large can the emitting source of light be?
a. about 10 light-years across
b. About 10 parsecs across
c. About 10 AU across
d.
About 10 light-hours
across
e. One cannot tell because the answer
depends on how far away the object is
58. How does the unified model of active
galaxies account for the differences between the various kinds of active
galaxies?
a.
The sort of object
that we see depends on the angle at which we view its central engine.
b. The sort of object that we see
depends on the mass of the central black hole.
c. The sort of object that we see
depends on the size of the central accretion disk
d. The sort of object that we see
depends on the strength of its central magnetic fields
e. The sort of object that we see
depends on the age of the object
59. 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 gravitationally bound to each other.
60. Astronomers have discovered multiple
images of the same quasar close together in the sky. Such multiple images form when:
61. The Drake equation attempts to
determine:
62. Current searches for extraterrestrial
life employ:
63. The Miller-Urey experiment
demonstrated that:
64. Which systems should astronomers
searching for intelligent life study to maximize their chances of success?
65. Pair production can only occur if:
66. What happened when the Universe was
about 10-15 minutes old?
a. The strong nuclear force and the
weak nuclear force decoupled from each other.
b.
It was the end of the
“nuclear” epoch when most of the helium in 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.
67. What is the effective temperature of
the cosmic microwave background radiation?
a. 3 billion degrees Kelvin
b. 3 million degrees Kelvin
c. 3 thousand degrees Kelvin
d. 3 hundred degrees Kelvin
e.
3 degrees Kelvin
68. Annihilation of electron and
positron produces:
69. What is the current epoch of the
Universe?
a. Planck
b. Particle
c. Nuclear
d. Atomic
e.
None of the above
70. The flatness problem arises because
Ω0 is very close to:
a. 70 km/s/Mpc
b. 3 K
c. p
d.
1
e. G – the gravitational constant
71. What is the horizon problem?
a. The Universe seems to have a boundary
beyond which no matter exists. This
violates the cosmological principle.
b.
Regions of the
Universe, which in standard cosmology are not in causal contact, have similar
properties such as temperature.
c. The size of the observable Universe
is much smaller than the size implied by the age of the Universe and the speed
of light.
d. The Universe seems to have no
curvature.
e. An almost complete absence of
anti-matter in the observable Universe.
72. Why are current theories unable to
describe the Universe during the Planck era?
a.
We do not yet have a
theory that combines quantum mechanics and the theory of general relativity.
b. We do not yet understand the
properties of antimatter.
c. We do not know how much energy
existed during that time.
d. We do not yet understand the properties
of quark matter.
e. The Planck era was the time before
the Big Bang, and we cannot describe what happened before that instant.
73. What is cosmic inflation?
74. As the Universe evolved – expanded –
after the Big Bang, it changed from a “Radiation-dominated era” to a “Matter-dominated
era.” Why?
75. Some recent measurements of the
expansion rate of the Universe suggest a problem with our standard idea that
the Universe should be expanding. What
is the problem?
76. What does Hubble’s Law imply about
the history of the Universe?
77. The redshift of galaxies in the
Universe is correctly interpreted as:
78. What is the meaning of isotropic
Universe?
79. The cosmic microwave background
radiation comes from a time in the evolution of the Universe:
80. Which of the following is important
for explaining why the sky is dark at night (the Olbers’ paradox)?
81. A cosmic triangle in an open Universe:
82. The spectrum of a quasar can contain
many absorption features due to hydrogen with different redshifts. Why?
a.
These
features form as some of the light from the quasar gets trapped in the
foreground black holes.
b.
These
features form because the gas in the accretion disk around the central black
hole moves with different speed, which depends on the distance from the black
hole.
c.
These
features are “contamination” of quasar’s light caused by the foreground stars.
d.
These features form as
the light from the quasar passes through multiple foreground clouds of
gas.
e.
These
features form as the light from the quasar makes multiple loops around the
Universe.
83. What is Einstein’s ring?
a.
Aggregate
of dark matter around the Milky Way
b.
Another
name for the cosmological horizon
c.
A
galaxy with a ring-like appearance caused by a collision with another galaxy
d.
Very
bright and nearby planetary nebula
e.
An example of
gravitational lens
84. Why does the Cepheid “standard
candle” have limited usefulness beyond about 20 Mpc?
a. Distant galaxies are seen in the
past when Cepheid variables appeared differently than they do today.
b. Distant galaxies are so young that
they do not contain Cepheid variables.
c.
Cepheid variables are
too faint to be seen beyond that distance, even with the Hubble Space
Telescope.
d. The light variability of Cepheid
variables diminishes with distance so they do not appear to vary there.
e. Older distant Cepheid variables are
of Population II, where the period-luminosity relation no longer works.
85. The greatest variation in size,
mass, and luminosity occurs in which type of galaxy?
a.
Irregular
b.
Elliptical
c.
Spiral
d.
Barred
spiral
e.
All
types have a similar variability
86. White-dwarf supernova is a good
standard candle for distance measurement for all of the following reasons
except one. Which one is it?
a.
All
white-dwarf supernovae involve explosions of stars of nearly the same mass.
b.
White-dwarf
supernova is so bright that it can be detected even in very distant galaxies.
c.
The
spectrum of a white-dwarf supernova is distinct from that of a core-collapse
supernova allowing astronomers to distinguish between these two types.
d.
The
light curve of a white-dwarf supernova is distinct from that of a core-collapse
supernova allowing astronomers to distinguish between these two types.
e.
White-dwarf supernova
can only occur in a globular cluster.
87. Approximately how far is the Sun
from the center of the Galaxy?
a. 28 light-years
b. 280 light-years
c. 2,800 light-years
d.
28,000 light-years
e. 28 million light-years
88. Most of the stars that you see on
the night sky are in the:
a.
Galactic disk
b.
Galactic
halo
c.
Galactic
bulge
d.
Galactic
center
e.
Galactic
corona
89. What is meant by the singularity of
a black hole?
a.
There
are no binary black holes – each one is isolated.
b.
An
object can become a black hole only once, and a black hole cannot evolve into
anything else.
c.
It is the center of a
black hole, a place of infinite density where the laws of physics cannot
describe the conditions.
d.
It
is the edge of a black hole, where one could leave the observable Universe.
e.
It
is the “point of no return” of a black hole; anything closer than this point
will not be able to escape the gravitational force of a black hole.
90. From an observational standpoint,
what is a pulsar?
a.
A
star that slowly changes its brightness, getting dimmer and then brighter with
a period of anywhere from a few hours to a few weeks.
b.
An object that emits
flashes of light several times per second or more, with near ideal regularity.
c.
An
object that emits random “pulses” of light that sometimes occur only a fraction
of a second apart and other times stop for several days at a time.
d.
A
star that changes color rapidly from blue to red and back again.
e.
An
object that emits pulses of neutrinos several times per day.
91. The heaviest of all nuclei formed:
a.
By neutron capture
during a core-collapse supernova
b.
During
a nova explosion
c.
During
a helium flash
d.
During
carbon burning in the giant stage
e.
During
a triple alpha process
92. Some regions of the Milky Way’s disk
appear dark because:
a. There are no stars there.
b.
Stars in that
direction are obscured by interstellar gas and dust.
c. Stars in that direction are obscured
by dark matter.
d. The magnetic field has directed the
polarized light away from these regions.
e. There are numerous black holes there
that capture all the starlight behind them.
93. Which two “ingredients” are needed
to make an emission nebula (also called an HII region)?
94. Suppose you see two main-sequence
stars of the same spectral type. Star 1
is dimmer in apparent brightness than star 2.
What can you conclude?
95. If the distance between us and a
star is doubled, with everything remaining the same:
96. By measuring stellar parallax angle,
an astronomer can determine:
97. What feature on an H-R diagram
allows an astronomer to measure the age of a stellar cluster?
98. A change in a star’s __________
causes its location on an H-R diagram to change.
99. How would sunspots appear if you could
magically remove them from the Sun?
100.
Which
statement about the Sun is false?