Use these questions to test your understanding of the material for the second
exam. If you get them wrong, you will be linked back to the relevant part of the notes. Be
sure you study them thoroughly (don't just get a quick fix for your mistake) so your
overall understanding is improved.
1. The Sun has been able to produce energy for billions of years by
a. a chemical process similar to burning coal b. gravitational contraction c. absorbing light from distant stars
d. nuclear fusion e. none of the above
2. The Sun's output is so stable because
a. pressure of Sun's gas just balances gravitational contraction
c. the Sun doesn't produce much energy
e. the Sun has only small sunspots
3. Although deep inside the sun, energy is carried by photon streaming, energy is carried to the surface of the sun
c. by convection, like boiling
4. If we have a container of hydrogen gas sitting in a laboratory on Earth, why doesn't it turn into helium?
a. because trace elements are required
b. because the temperature and pressure are too low
c. because the hydrogen needs other isotopes
d. because an electric spark is needed
e. it will become helium if you wait long enough
5. Hydrogen fusion can produce energy because
b. the atoms join together into bigger molecules, and the molecular binding energy is released
d. the helium that is produced has been heated to very high temperature
e. the high pressure where the fusion takes place yields some of its energy
6. To measure the luminosity of the sun from the earth, we need to measure
a. Earth's distance from the sum
b. the flux Earth receives from the sun (the apparent brightness of the sun at the earth)
7. The basic properties that control the current status of a star are
a. age, mass, initial composition b. temperature, distance, color
c. spectral type, composition, temperature d. distance, magnitude, color
8. A star will become a red giant when
a. it begins to convert H to He b. when its composition changes
c. when it can no longer convert H to He in its core d. when it gains mass
9. A star may be a variable star because
a. it alternately expands and contracts b. planets fall into it and block the light
c. it makes more or less dust d. its mass changes
10. The oldest stars are most likely to be
a. the brightest stars b. the most massive stars c. the hottest stars
d. the least massive stars e. the stars with largest percentage of hydrogen
11. The lower limit on the size of a star is set by
a. the size of cloud fragment that can form b. the gravitational field of a cloud
c. the amount of H that can coalesce d. the mass require to get the core hot enough for conversion of H to He
12. The upper limit on the size of a star is set by
a. the size of cloud fragment that can form b. the gravitational field of a cloud
c. the stability against photon pressure d. the mass require to get the core hot enough for conversion of Si to Fe
Here are the properties of three main sequence stars:
1.) Barnard's Star T= 3370° K L=0.005 LSun
2.) Sun T= 5800° K L = 1 LSun
3.) Spica T=26,000° K L = 23,000 LSun
13. List these stars in order of increasing mass.
a. Spica, Sun, Barnard's Star b. Spica, Barnard's Star, Sun c. Barnard's Star, Sun, Spica
d. Barnard Star's, Spica, Sun e. Sun, Barnard's Star, Spica
14. Under what circumstances can a star convert oxygen to silicon?
a. when it makes dust in its outer layers
b. when it reaches the main sequence
c. when it becomes a white dwarf
d. when it becomes a black hole
e. when the core of a massive star gets hot enough
15. A white dwarf does not collapse further because
a. it is converting H to He b. it is converting He to C
c. its electrons can't be squeezed together any more d. it is made of dark matter
16. Pulsars vary their light output by
a. alternately expanding and contracting b. alternately heating up and cooling off
c. sweeping a light beam across our line of sight d. converting H to He
17. Planetary nebulae are
a. in the process of forming planets b. molecular clouds
c. the ejected outer layers of a dying star d. the precursors to black holes
e. the result of protostars having disks
18. A neutron star is mostly neutrons because
a. the protons it used to contain have collected into a proton star
b. it has a proton core, but neutrons cover the surface
c. the huge pressure has caused its electrons to merge with its protons to make neutrons
d. antiprotons have annihilated all the protons it used to contain
e. the protons have collapsed into a black hole in its core
19. If you add mass to a white dwarf to "bulk it up" above 1.4 solar masses,
a. it will get smaller and smaller and finally collapse into a neutron star
b. it will develop strong coronal lines because of its high surface temperature
c. it will increase in radius in proportion to the cube root of the additional mass
d. the new matter will cause it to cool on the surface and get fainter
e. the matter will disappear beyond its event horizon and we will not know what happens
20. The most important aspect (to us) of the material ejected by dying stars is
a. it makes beautiful nebulae that inspire our interest in astronomy
b. it shields us from dangerous radiation emitted by the dying star itself
c. it reduces the mass of the star so its end is less violent
d. we are made of material ejected by dying stars a long time ago
e. it causes interstellar extinction
The next five questions refer to the following graph.
21. Which letter indicates where giant stars would be found in the HR diagram?
22. Which indicates the location of white dwarfs?
23. Which indicates where spectral type would be found?
24. Which indicates the location of the main sequence?
25. Which indicates where luminosity would be found?
26. What is the closest location for finding material formed in a supernova explosion?
a. the Milky Way b. the Orion nebula c. the Crab Nebula d. the Sun e. your own body
27. Your best bet for finding a black hole is to search for
a. a region of space where nothing can be seen
28. A nova is powered by
29. A remarkable observation from the 1987A supernova was
a. the detection of gravity waves b. the detection of neutrinos
c. the detection of a pulsar d. the detection of a black hole
30. We know that the Crab nebula is a supernova remnant because
a. it contains a pulsar b. Chinese astronomers witnessed the explosion c. it emits lots of x-rays
d. its gas is moving very rapidly e. all of the above
31. The Crab Nebula pulsar is spinning
e. at a rate determined by its mass
32. The cooling rate in SN 1987A showed that
a. it was full of very hot gas that could not lose energy efficiently
b. it contained huge amounts of cobalt
c. a massive star was still powering things in its core
d. it was really a type 1 supernova
e. not all the neutrinos escaped quickly
33. If you took spectra of a supernova remnant, you would see
a. only H and He b. many elements such as O, C, Si c. only cool gas
d. only dust e. both c. and d.
34. The elements like oxygen and iron in the earth got there because
a. they were swept up as the early sun went through a region with lots of these elements
c. they were created in the early stages of the Big Bang
e. they were pulled from a passing star by the sun's gravitational field
35. The low luminosity stars on the main sequence
a. are the hottest b. have the shortest lifetimes
c. are the coolest d. have the most helium
36. The Sun will end its life as
c. a black hole d. a brown dwarf
37. Which of the following has the smallest diameter?
a. a hot star b. a cool star c. a white dwarf d. a neutron star e. Earth38. Which of the following can escape from inside the event horizon of a black hole?
a. particles of matter b. particles of antimatter c. quarks d. gamma rays e. none of the above
39. Supernovae occur when
a. the core of a star blows up
c. the outer layers of a star fall into a black hole, releasing a lot of energy
d. a catastrophe in the stellar nucleus sends a heat pulse out through the star
e. the neutrinos escape from the core of the star, causing it to collapse
40. Massive stars cannot burn iron because
a. they cannot form iron to burn
b. iron does not react with other elements
c. they cannot reach high enough temperatures to burn iron
d. when iron burns, it removes energy and causes the star to collapse
e. rather than buring in fusion, the iron nucleus splits into lighter elements
41. Observational proof that neutron stars exist is provided by
a. black holes b. hot stars c. pulsars d. cool stars e. planetary nebulae
42. The escape velocity at a black hole's event horizon is
a. the same as from the earth b. the speed of light
c. the same as from the Sun d. different for different elementary particles
e. highly dependent on the black hole's characteristics
43. Proof of Einstein's theory of how gravity can affect light is given by
a. the size of the Earth b. the rate at which stars produce energy
c. the bending of star light near the limb of the Sun d. the speed of light
e. the existence of white dwarfs
44. Heavy elements like silver and gold are formed
a. on planetary surfaces b. in planetary nebulae
c. in main sequence stars d. in supernova explosions
45. Stars on the main sequence all
a. are in hydrostatic equilibrium b. have the same mass
c. have the same temperature d. have the same diameter
e. there is no property in common among main sequence stars
46. The diagram at the right shows the evolutionary track of a star
like the Sun after it leaves the main sequence. At Point A, the star is
a. burning hydrogen in its core and helium in a shell
b. burning hydrogen in a shell around a collapsing core
d. burning hydrogen in its core
47. At Point C, the star is
a. burning hydrogen in its core and helium in a shell
b. burning hydrogen in a shell around a collapsing core
d. burning hydrogen in its core
48. At Point B the star is
a. burning hydrogen in its core and helium in a shell
b. burning hydrogen in a shell around a collapsing core
d. burning hydrogen in its core
49. The planets in our solar system are thought to have come from
a. clumps of rocky material that exist between the stars
b. the same cloud of gas and dust in which the Sun formed
c. a cloud of gas in the Orion nebula
d. the Sun (they were flung out of the fast-spinning young sun)
50. As the solar nebula collapsed, it became a disk because
b. the initial cloud was disk shaped
c. the Sun's gravity pulled the nebula material into the ecliptic plane
d. the self-gravity of the nebula pulled the material into the ecliptic plane
51. The outer planets are mostly large and gaseous because
a. beyond the frost line, hydrogen froze to form the jovian planets
d. the disk's spin flung lighter materials farther from the Sun
52. Because of the temperatures in the protoplanetary disk,
a. rocks, metals, and ices (hydrogen compounds) froze in the inner region only
c. rocks and metals froze in the inner region only, and ices froze in the outer region only
53. As the solar nebula collapsed under its own gravity,
54. You are sent to find dense and rocky planets. Where in the Solar System should you look
a. very far from the sun b. only in the middle
c. close to the sun d. in circular orbits
e. in regions with lots of moons
55. A key characteristic of the cloud from which the Solar System formed was its
e. ability to have chemical reactions
56. Planetary systems form
a. within the dense disks of material surrounding very young stars
b. when young stars capture smaller bodies that foumed near them
c. in near-collisions of young stars that pull matter our of them
d. in eruptions of material from stars settling onto the main sequence
e. from convection cells in jets from young stars
57. The current arrangement of continents and oceans on the earth’s surface
a. has been present since the earth formed b. is the result of meteor collisions
c. is the result of the formation of the moon d. is the result of motion of plates
58. The earth's atmosphere has
a. changed only due to the action of humans b. remained the same since the earth formed
c. changed due to meteors d. changed due to the moon
e. changed due to volcanoes, rainwater induced chemical reactions, and photosynthesis
59. A planet that is differentiated
a. was put together from different bodies with distinct compositions
b. formed from a dense, metallic object to which rocky debris got added later
c. developed a surface of low density rocks deposited through volcano eruptions
d. will have plate tectonics as a result
e. must have been sufficiently molten that the denser materials sank to the center
60. The magnetic field of the earth
a. has remained constant since the planet formed
b. fluctuates in strength and reverses direction about every 20,000 years
c. has been steadily decreasing as the core of the earth cools
d. is produced by convection in the hot mantle of the planet
e. proves that there is a solid core to our planet
61. The most useful means to explore the crust and mantle of the earth is
a. studying earthquakes and seismic waves
b. drilling deep holes down into the earth
c. going down in very deep mines and making measurements
d. studying the motions of the continents
e. comparing the properties of the earth with those of other planets
62. The convection of hot rocks in the mantle of the earth occurs because
a. water deep within the earth boils and forces rocks upward
b. the mantle is stirred by the magnetic field as the earth spins
d. the motions of the continents stir up the rock underneath
e. the effects of tidal forces from the moon
63. We know the interior of the earth is liquid because
a. on a quiet night, you can feel it slosh
b. the way the earth wobbles on its axis shows it is not all solid
c. deep gold mines reach the liquid layer
d. earthquake waves that can't go through liquids are blocked by the interior of the earth
e. it is larger through the equator than through the poles
64. If there were no plate motions and continent building,
a. the earth would look pretty much like it does now
b. everything would be under water
c. only the polar caps would stick out of the water
d. the continents would still be there, but the mountains would be much lower
65. Continents stay at the surface of the earth because
b. they just happen to be there now but will sink as part of the convection of the mantle
c. upward mantle convection over hot spots keep them at the surface
d. they are made of low density rock that floats on the mantle
e. water is heated and turned to steam at their bases
66. Continental motions were first measured directly by
a. ancient mariners, who noticed that the times to cross the oceans were changingc. astronauts taking pictures downward of the continents
d. measuring the motions of ocean plates where they were going under continents
e. surveying accurately across seismic faults
67. Craters are caused by
a. objects crashing into a planet's surface
c. bubbles rising from a planet's interior
68. What is the main reason Mercury is hotter than the Moon?
a. Mercury has a slower rotation rate b. Mercury is closer to the Sun
c. Mercury absorbs sunlight better than the Moon d. Mercury has more greenhouse gases than the Moon
69. The approximate age of the Solar System is
a. 4500 years b. 4.5 billion years c. 4.5 million years d. 10,000 years
70. A rock sample is analyzed and found to have only 25% as much of a radioactive element as it would have been predicted to contain originally. The half-life of the radioactive element is 8x108 years. How old is this rock?
a. 8x108 years b. 1.6x109 years c. 2x108 years d. 3.2x109 years
e. cannot be computed from the information given
71. The lack of an atmosphere on the moon implies that
a. it never had one b. it escaped because of the moon's weak gravity
c. it froze on the surface d. it got ejected during crater formation
e. the moon could never have been part of the earth
72. An object with no atmosphere or erosion processes is found in the Solar System with fewer craters on its surface than the lunar highlands. This object
a. has had a new layer deposited on its surface since it formed
73. Mercury's surface looks a lot like
a. the surface of Jupiter b. the surface of Mars c. the surface of the moon d. the surface of the earth
e. like no surface in the Solar System
74. Observations of the Moon show that the lunar maria have only 3% as many craters as the lunar highlands. It can be reasoned that
a. lunar lava flowed across the surface BEFORE most of the Moon's larger craters were created
b. the lunar maria must be about 4.6 billion years old
c. comets have collided with the Moon more often than with Earth
d. lunar lava flowed across the surface AFTER most of the Moon's larger craters were created.
75. The composition of the moon is
e. similar to the earth's crust
76. An important scientific result from the Apollo program to send astronauts to the moon is
a. pictures of the stars without interference from the atmosphere of the earth
b. discovery of the effects of coronal mass ejections on the energetic particle flux hitting Earth
d. determining the effects of a planet with low gravity on human health
e. scouting the moon for potential mineral deposits for future mining
77. Studying the craters on the moon shows that
a. the rate of bodies striking the earth fell rapidly after the first 500 million years
b. the rate of bodies striking the earth has been about the same throughout its life
d. the craters do not tell us anything useful about bodies striking the earth
e. the kind of body creating the craters has changed over time
78. Greenhouse gases ____________
a. absorb visible light and transmit infrared light b. absorb ultraviolet light and transmit visible light
c. absorb infrared light and transmit visible light d. absorb X-rays and transmit infrared light
79. What would the temperature of a planet be if it reflected nearly all the sunlight?
a. it would be very, very cold
b. it could be cold or warm, depending on its distance from the Sun
c. it could be cold or warm, depending on the amount of greenhouse gases
80. Mars' surface temperature would be higher if _______
a. it reflected more sunlight b. it were farther from the Sun
c. its atmosphere contained more greenhouse gases d. it rotated more quickly
81. The only body other than Earth to show signs of running water on its surface is
a. Venus b. Mars c. Mercury d. the Moon e. all inner planets have water on their surfaces
82. Volcanoes on Mars
a. don't exist b. are much larger than on Earth c. are much smaller than on Earth
83. The canals on Mars are
a. long and thin geological features
b. the product of ancient intelligent life, used for irrigation
c. an illusion caused by observers trying too hard to see features on the planet
e. places where the surface has cracked into long fault lines
84. Ultimately, the reason the Martian volcanoes grew to their current sizes is
a. just a chance of Martian geology
b. because ancient Martian oceans eroded the land around them
c. because gravity is weaker on Mars than on the earth
d. a result of the lower atmospheric pressure on Mars
e. because Mars is too small to retain significant interior heat
85. "Terraforming" refers to
a. modifying the atmosphere of a planet to make its climate more like that of the earth
b. making a specialized kind of pottery out of a rare kind of clay
c. sending a spacecraft to another planet to colonize it
d. depositing a sample of the earth on the moon as a momento for future astronauts
e. recovering areas in the arctic to make farming in them possible
86. The surface of Venus
a. is completely unknown to us
b. is dominated by impact craters, similar to Mercury and our moon
c. has features suggesting that the planet once had abundant water
87. Why did astronomers in the 19th century believe that the solar system was close to the center of the Milky Way?a. we are close to the center
b. they did not have photographic plates to detect very faint stars
c. their telescopes were too small to see the whole system
d. they needed infrared detectors
e. they did not realize how interstellar dust cut off their view
88. A "standard candle" for an astronomer is
a. a special candle of constant brightness maintained at the Bureau of Standards
b. an astronomical object whose luminosity can be determined independent of knowing its distance
c. a barred spiral galaxy
d. a votive candle of the usual size and wax content
e. a variable red supergiant star
89. Henrietta Leavitt's period luminosity relation for RR Lyrae stars proved important because:
b. it was the first significant astronomical discovery by a woman
c. it explained why some star fields looked different in pictures taken at different times
e. it showed that they moved on the HR diagram
90. The sun is located
a. in the outer part of the Milky Way's disk
b. in the halo of the Milky Way
c. near the center of the Milky Way
d. at an unknown location within the Milky Way
91. The period-luminosity relationships for RR Lyrae and Cephid stars were easier to establish for stars in the Magellanic Clouds (nearby external galaxies) because
a. there are more of these stars in the Magellanic Clouds than in the Milky Way
b. they were easier to see in the Magellanic Clouds than in the Milky Way
c. the ones in the Magellanic Clouds are all at about the same distance
e. their proper motions are smaller, making comparisons over time with other stars more accurate
92. The gas in an HI region is comprised of
a. hydrogen gas with electrons in the ground state b. ionized hydrogen gas
93. A molecular cloud is
a. a large, cold, dense collection of interstellar gas and dust
b. interstellar dust that is lit up by a nearby star and scatters some of the light toward us
c. an interstellar cloud made purely of complex molecules, mostly containing carbon
d. a region where a very hot star is ionizing the nearby gas
94. A newly formed massive, hot star changes the surrounding interstellar gas into
b. a glowing cloud of excited gas called an HII region
c. a dark globule seen as a shadow against the background light
95. Interstellar dust makes the things behind it look
d. it blots them out completely
96. A "reflection nebula" is
a. a cloud of interstellar grains aligned to reflect light similarly to a mirror
c. a cloud of interstellar material that lets us look into regions we cannot see directly
d. an interstellar cloud that absorbs energy from nearby stars and emits it in the infrared
e. an interstellar cloud that is lit up by scattering light toward us from a star near the cloud
97. An HII region can be identified from
c. from the reddening it imposes on objects behind it
98. What do we call the bright, roughly spherical, collection of old stars around the center of the Milky Way?
a. disk
b. halo
c. bulge
d. spiral arms
e. dark matter
99. Stars with high concentrations of elements heavier than hydrogen and helium
a. are likely to be very old
b. are found in globular clusters
c. are likely to have formed relatively recently
d. are members of population II
e. have very low mass
100. In the Milky Way, most of the young stars are found in the
a. halo b. bulge c. bar d. disk e. tidal tails
101. Molecular clouds are found mostly in the ________ of the Milky Way and other galaxies
a. bulge b. halo c. center d. globular clusters e. spiral arms
102. The best place to look for stars just beginning to form is
a. in empty space b. in a molecular cloud
103. Which physical force dominates the process of star formation?
a. strong nuclear b. weak nuclear c. electrical d. gravitational e. reactional
104. Disks form around young stars
a. if the cloud from which the star forms is too massive for all of it to fall into the star
b. when the new star passes through a dense cloud and it is attracted to the star
c. from material that was spinning around the protostellar core too fast to fall into the star
d. when a second star that formed in orbit breaks up
e. disks are something that only form around older stars
105. To form a real star, an object must be massive enough to
a. have enough gravity to hold planets in orbit
d. create enough pressure and heat in its core for hydrogen fusion
e. burn hydrogen and helium into heavier elements
106. Star formation is often aided by
a. planets passing through a molecular cloud and upsetting its equilibrium
b. a gravitational vibration caused by thermal instability in interstellar gas
c. a supernova explosion near a molecular cloud that compresses it and starts fragments collapsing
d. heating of an interstellar cloud by a nearby young star
e. centrifugal forces caused by spinning cloud fragments
107. A very large clump of interstellar matter
b. can make a star up to nearly any mass range
c. takes an extra-strong initial event to start it collapsing
d. collapses into a star particularly slowly because it is so big
e. can explode as a supernova rather than becoming a star
108. Clumps of matter with too little mass to form stars
a. seldom collapse - they just stay part of the interstellar medium
b. usually join together to form stars
109. When clumps first collapse into young stars,
a. they cannot burn hydrogen because it has not settled into their cores yet
b. they cannot burn hydrogen until a spark ignites it
c. their activity level needs to rise before they can burn hydrogen
d. their cores must shrink and heat up to burn hydrogen
e. the hydrogen must be converted from molecular to atoms form to burn
110. These days, astronomers depend on ____________ for obtaining new observations of photons from the stars
a. their eyes b. refracting telescopes c. electronic detectors d. discovering notebooks of previous astronomers
111. Astronomers like big telescopes because
a. big telescopes make them feel important
b. big telescopes can see smaller details (have higher resolution)
c. they actually prefer small ones because they are easier to move around
d. big telescopes can carry heavier instruments than small ones
112. Observatories are put in in space
a. to get them closer to the stars
b. so they can observe night and day
c. because they can be pointed more accurately there
d. to get above bad weather so observations are not interrupted by clouds
e. to get above the atmosphere and its absorption of photons