NAME __________________________________ LAB # ______________________
Astronomy 1001 - Final Exam, May 14, 2005 Dr. Robert D. Gehrz - Spring 2005
Read Instructions Carefully:
1. MARK THE ANSWERS YOU CHOOSE ON THIS TEST AS IT IS YOUR ONLY OPPORTUNITY TO CHECK WHICH ANSWERS YOU GOT RIGHT OR WRONG. This will not be done for you at a later time in the departmental office. Exams will be available in room 451 Physics during Summer Term TA office hours. In order to get your test back, your LAB section number must be indicated in the space provided above (listing just the meeting time and day of the week for your lab is not sufficient).
2. Print your NAME, ID # and SECTION # on your answer sheet where appropriate. Your SECTION # should read 02. All three items are necessary for the proper scoring and
computer transfer of your scores.
3. Use a pencil, make your marks dark and neat, and erase thoroughly.
4. There is only one answer to each question. Choose the best answer.
5. You may use this test for scratch paper.
6. One page (two sides) of notes is allowed for the exam.
Multiple Choice (2.5 pts. each)
1. The explosion of Supernova 1987A seemed to confirm the following facts about the evolution of massive stars:
a. neutrinos are produced when the stellar core collapses
b. the very heavy elements (e.g., heavier than iron. are produced in the explosion)
c. dust grains with the composition of the surfaces of the terrestrial planets condense in the expanding ejecta
d. all of the above
2. A more luminous Cepheid variable
a. takes less time to pulsate
b. takes more time to pulsate
c. changes its time of pulsation
d. has no pulsation
3. The occasional symmetric brightening of the light from stars in the Large Magellanic Cloud, a companion galaxy to the Milky Way, is caused by:
a. stellar explosions
b. the gravitational lense effect of small, dense stars orbiting in the halo of the Milky Way
c. cepheid variables
d. the decay of interstellar protons
4. Consider two main-sequence stars that have different masses. You can correctly infer that the more massive star will have a:
a. lower luminosity and shorter lifetime
b. higher luminosity and shorter lifetime
c. higher luminosity and longer lifetime
d. lower luminosity and longer lifetime
5. What makes a high-mass star's core collapse?
a. energy from its outer layers compresses its core
b. the only thing that can make a star's core collapse is a collision with another star
c. massive stars develop iron cores that cannot fuse anymore, so the core collapses under gravity
d. massive stars' cores don't collapse. They expand and become planetary nebulas
6. What is the cosmic microwave background? It is
a. radio noise from Seyfert galaxies
b. radiation from hot gas in intergalactic space
c. radiation from the first stars formed when the Universe was young
d. background noise from radiation created in the young Universe
7. Which of the following elements is thought to be made ONLY in a supernova explosion?
a. Iron b. Oxygen c. Carbon d. Uranium
8. Why do astronomers believe the Universe is expanding?
a. they see a red shift in the spectral lines of distant galaxies
b. they can see the disks of galaxies getting smaller over time
c. they can see distant galaxies dissolve, pulled apart by the expansion of space
d. all of the above
9. An eclipsing binary star like Algol is a pair of stars that orbit around each other with the plane of the orbit oriented so that an observer on Earth can actually see the stars cross in front of one another. From this orbital motion, one can directly measure the stars':
a. radii b. luminosities c. masses d. distances e. both a and c
10. Comets and asteroids are likely
a. some of the oldest objects in our Solar System
b. some of the most newly formed objects in our Solar System
c. are a mixture of new and old objects
d. none of the above; we have no way to determine their age
11. What is a black hole?
a. a white dwarf that no longer radiates light
b. the collapsed core of a very massive star whose gravitational force is so great that not even light can escape it
c. a very deep lunar crater
d. the burned-out remnant of a low-mass star
12. Although it hasn’t been observed (yet), why do astronomers think that Milky Way may contain "dark" material?
a. theory predicts that there should be more black holes than we've so far detected
b. the galaxy's gravity seems too big for the mass astronomers can see
c. due to its large size, the light from stars on the other side of the Milky Way has not reached us yet
d. astronomers have detected neutrinos from unseen sources
13. Ninety percent of stars in the Hertzsprung-Russell Diagram are
a. white dwarfs b. on the main sequence c. red giants d. binary stars
14. What observation convinced Hubble that M 31, the Andromeda Galaxy, was indeed a separate galaxy?
a. its trigonometric parallax
b. its large angular diameter
c. its spiral structure
d. cepheid variables within its spiral arms
15. Two important characteristics of sunspots are:
a. low temperature and intense magnetic fields
b. high temperature and intense magnetic fields
c. high temperature and weak magnetic fields
d. low temperature and no magnetic fields
16. The discovery of the cosmic microwave background radiation supports the basic Big Bang model because it implies:
a. a hot state in the past
b. an isotropic universe
c. a homogeneous universe
d. all of these are correct
17. In the standard hot Big Bang model, matter in the form of elementary particles:
a. always existed in its present forms
b. is created from electromagnetic energy (photons)
c. is created from other unknown forms of matter
d. exists in large clumps, like stars
18. The value of the Hubble Constant tells us directly:
a. the expansion age of the universe
b. the overall geometry of space-time of the universe
c. that we lie at the center of the expanding universe
d. that the expansion of the universe is an illusion, and not real
19. A star leaves the main sequence when
a. nuclear fuel in its core can supply enough energy to stop its collapse
b. it collapses, and its envelope becomes degenerate
c. it stops fusing nuclear fuel in its core and starts to expand
d. it forms planets
20. Low-mass stars like the Sun probably do not form iron cores during their evolution because
a. all the iron is ejected when they become planetary nebulas
b. their cores never get hot enough for them to make iron by nucleosynthesis
c. the iron they make by nucleosynthesis is all fused into uranium
d. their strong magnetic fields keep their iron in their atmospheres
21. The distribution of dark matter in the Universe is assessed by looking at the
a. peculiar velocities of halo stars
b. peculiar velocities of galaxies
c. angular momentum of galaxies
d. angular momentum of stars
22. The unification of three fundamental forces into a single grand force would be readily observable
a. only during the very young Universe
b. only during the current Universe
c. at all stages of the Universe
d. at no time, except in the artificial conditions of particle accelerators
23. By the time the Universe was five minutes old,
a. the four fundamental forces had separated
b. there existed more matter than antimatter
c. materials such as helium could form through nucleosynthesis
d. All of the above
24. The Drake Equation gives an estimate for the possible number of
a. civilizations in the Galaxy
b. planets in the Galaxy
c. stars in the Galaxy
d. galaxies in the Universe
25. The Universe is
a. Shrinking b. Expanding c. staying the same size d. revolving
26. Our Galaxy is
a. a spiral galaxy b. an elliptical galaxy c. an S0 galaxy d. an irregular galaxy
27. Most globular clusters in our Galaxy are found
a. within the central bulge
b. within the disk
c. within the halo
d. evenly distributed among all parts
28. Main sequence stars with the largest mass would be found where on the H-R diagram?
a. upper left b. lower left c. upper right d. lower right
29. In order to find the earth-sun distance in units such as kilometers, we:
a. bounce radar signals off the sun
b. bounce radar signals off the moon
c. bounce radar signals off Venus
d. know the light travel time from the sun to the earth
30. The primary transport system for heat to get from the core of our Sun to its surface, as evidenced by its "granular appearance" is:
a. radiation b. conduction c. convection d. levitation
31. The most massive element formed by nuclear fusion in stellar interiors is
a. carbon b. oxygen c. iron d. uranium
32. A nova explosion (choose all answers that apply):
a. results from a runaway nuclear reaction on the surface of a white dwarf that has been accreting matter in a binary star system
b. is caused by the core collapse of a very massive star
c. expels gas clouds that can condense small grains made of material that is similar to that found in the terrestrial planets
d. is more luminous that an entire galaxy
e. can produce important amounts of some elements found in the solar system
33. What is the difference between emission and absorption in terms of what happens to an electron in an atom?
a. In emission, the atom's nucleus goes from a lower to a higher orbit; in absorption, the nucleus goes from a higher to a lower orbit.
b. In emission, the atom's nucleus goes from a higher to a lower orbit; in absorption, the nucleus goes from a lower to a higher orbit
c. In emission, the electron goes from a lower to a higher orbit; in absorption, the electron goes from a higher to a lower orbit.
d. In emission, the electron goes from a higher to a lower orbit; in absorption, the electron goes from a lower to a higher orbit.
34. Cooler, less luminous main sequence stars have
a. higher masses
b. lower masses
c. the same masses as hotter stars
d. masses that vary widely
35. What is the celestial equator?
a. A band of constellations through which the planets and Sun appear to move
b. The line that the sun traces across the celestial sphere
c. The extension of the Earth's equator on the celestial sphere
d. The cycle of lunar phases
36. What is inflation all about in cosmology? This is the idea that the
a. force of gravity suddenly grew stronger in the distant past
b. Universe increased dramatically in size in an extremely brief period of time
c. number of galaxies we see at large distances is greater than the number we can see near us
d. diameters of distant galaxies are much greater than those of galaxies near us
37. A neutron star can form when
a. the shell of a planetary nebula expands and dissipates, leaving behind the dead core of a red giant
b. a massive star is destroyed in a supernova explosion, leaving behind a collapsed core made of neutrons
c. an interstellar cloud collapses and starts burning hydrogen
d. the helium fusion reactions in the core of a red giant experience a thermal runaway
38. The gravitational force exerted by the Sun on the Earth is ____ the gravitational force exerted
by the Earth on the Sun.
a. greater than b. less than c. equal to d. unrelated to
39. Close to the center of our Galaxy,
a. the rotation rate is very fast
b. the rotation rate is very slow
c. dark matter can be seen
d. dark matter cannot be seen, but detected otherwise
40. The earth’s crust is broken into large plates that are in motion on its surface by the
a. moon’s gravitational pull
b. rotation of the Earth
c. rolling convective motions of the Earth’s mantle
d. precession of the earth’s axis of rotation
41. How are lunar craters formed?
a. Pieces of the Moon fall off, leaving holes in its surface
b. Solid bodies such as asteroids strike the Moon's surface
c. Craters are extinct volcanoes
d. Both a and c
42. One reason we infer that the earth's core is metallic is that:
a. the average density is greater than the surface density
b. the surface density is greater than the average density
c. most of the continents are made of metals
d. earthquakes can only occur if the core is metallic
43. Which concept below was NOT part of Kepler's laws?
a. The planet orbits are ellipses
b. The closer a planet is to the Sun, the faster it moves
c. Retrograde motion required use of epicycle
d. The sun lies at one focus of all elliptical planetary orbits
44. How are galaxies distributed in the Universe?
a. with uniform spacing between all individual galaxies
b. gathered together in groups, with uniform spacing between groups
c. gathered together in groups, with large-scale structure linking interweaving the groups
d. gathered together all in one group
45. Dark matter
a. does not produce light b. has no electric charge c. has gravity d. all of the above
46. An elliptical galaxy most likely forms from
a. the merger of two or more spiral galaxies
b. the natural evolution of a single spiral galaxy
c. the breaking apart of a single spiral galaxy
d. none of these -- ellipticals naturally formed on their own
47. How many positively identified fundamental forces exist in nature?
a. 1 b. 2 c. 4 d. an uncountable number
48. Proto stars (Gravitationally contracting “solar systems”} initially do not generate their internal energy by hydrogen fusion. How then do they heat up?
a. the light from nearby stars
b. gravitational energy from in falling material
c. fusion of hydrogen into helium
d. energy from their magnetic fields
49. What determines how long a star stays on the main sequence?
a. its temperature and mass
b. its luminosity and radius
c. its mass and luminosity
d. its radius and mass
50. What is a pulsar?
a. a rotating neutron star that emits radio waves in a narrow beam
b. a star whose luminosity changes as it swells and shrinks rhythmically
c. a star whose mass changes as it comes into contact with another star
d. a planetary nebula
51. What is the ecliptic?
a. A band of constellations through which the planets and Sun appear to move
b. The line that the sun traces across the celestial sphere
c. The extension of the Earth's equator on the celestial sphere
d. The cycle of lunar phases
52. Which of the following (A-D) are examples of an object accelerating?
A. an object at rest
B. an object in motion in a straight line at a constant speed
C. an object in motion in a straight line with increasing speed
D. an object moving in a circle at constant speed
a. A only b. All but A c. C only d. Both C and D
53. Why is the Moon's surface cratered but the Earth's not?
a. The Moon was bombarded with large rocks, but the Earth was not
b. Meteors bounce off the Earth's atmosphere
c. The Earth's surface once had craters like the Moon's, but they were obliterated by erosion and plate tectonics
d. Human activity on Earth has wiped out all traces of craters
54. Which of the following properties of the terrestrial planets distinguish them from the Jovian
or Giant planets?
a. High average density b. Distance from the sun c. Slow rotation d. all of the above
55. Galaxies come in three main flavors, which are
a. barred spiral, irregular, and Seyfert
b. Seyfert, radio, and quasar
c. spiral, elliptical, and irregular
d. old, young, and intermediate
56. What is the phase of the moon for a solar eclipse?
a. New b. First quarter. c. Full Moon. d. Third quarter
57. What is a gravitational lens?
a. a heavy contact lens
b. a massive object that bends the space around it, causing light to bend
c. an extremely massive refractor telescope
d. a lens that is affected by gravity
58. Why do we think that quasars are extremely distant?
a. their light varies rapidly
b. their spectra show immense red shifts
c. they are very bright
d. they are very faint
59. Which characteristic of a star determines all other its other characteristics and its evolution?
a. distance b. luminosity c. temperature d. mass
60. The Sun is supported against the crushing force of its own gravity by :
a. magnetic forces b. its rapid rotation c. gas pressure d. all of the above
61. Stars are continually forming in the Milky Way and other spiral galaxies by:
a. the collapse of supernova stars
b. implosions of star clusters
c. the gravitational contraction of small fragments in Giant Molecular Clouds of gas and dust
d. the interaction of colliding galaxies
62. The current thinking about the formation and evolution of galaxies is that:
a. elliptical galaxies are the youngest galaxies in the universe and that spiral galaxies and irregular galaxies are derived from them
b. all galaxies are the same age
c. most galaxies formed within the first three minutes of the expansion of the universe
d. the most massive galaxies have formed from the aggregation of smaller remnants
e. both b and d
63. What are the satellites of the outer planets thought to be composed of?
a. Hydrogen and helium
b. Hydrogen and methane
c. Water and carbon dioxide
d. Ice and rock
64. Relative to the horizon, as seen from the northern hemisphere, the stars daily:
a. rise in the east and set in the west
b. rise in the west and set in the east
c. move mostly in a northward direction
d. move mostly in a southward direction
65. The composition of stars is determined by analyzing
a. Doppler shifts b. brightness c. absorption spectra d. radius
66. What causes a solar eclipse?
a. The moon's shadow falls on a small portion of the earth
b. The earth covers the sun, as viewed from the moon
c. The sun's shadow covers the earth, as seen from moon
d. The earth's shadow falls on the full moon
67. The earth's core is more dense than the crust or mantle. This fact can be used to infer what about the earth's history?
a. The metals accreted first and then the silicates
b. Gravity has compacted the core and made it denser
c. The entire planet was molten at one time
d. The sun heated the earth more in the past then now
68. The earth's atmosphere has a large percentage of oxygen compared to that of the other
terrestrial planets. The main source of this atmospheric oxygen was:
a. the breathing of animals over billions of years
b. release of oxygen by plants over many years
c. volcanic out gassing from the earth's crust
d. A part of the atmosphere since the time of formation
69. Compared to the oldest stars in our Galaxy, the youngest stars will have
a. greater amounts of hydrogen.
b. greater amounts of massive elements.
c. higher luminosity.
d. lower luminosity.
70. The thinnest part of our Galaxy's disk is located along its plane and is characterized by
a. older stars b. younger stars c. dark matter d. globular clusters
71. On a galactic scale, stars form
a. very early in a galaxy's life
b. much later in a galaxy's life
c. before the galaxies themselves formed
d. all at once, at the same time the galaxies formed
72. The two most abundant elements in the sun are:
a. carbon and oxygen
b. helium and carbon
c. hydrogen and oxygen
d. hydrogen and helium
73. The halo of our Galaxy contains
a. globular clusters b. individual stars c. dark matter d. all of these
74. What is inferred to be the source of the sun's energy right now?
a. Fusion of hydrogen to helium in the core
b. Gravitational energy released by collapse
c. Fission reactions in the core
d. Chemical oxidation (burning) of materials such as carbon
75. Globular clusters are used to measure the
a. size of our Galaxy
b. mass of our Galaxy
c. temperature of our Galaxy
d. luminosity of our Galaxy
76. Most of our Galaxy is made up of
a. main sequence stars b. globular clusters c. interstellar dust d. dark matter
77. The motion of our Galaxy is measured by analyzing
a. 21-cm wavelengths due to hydrogen
b. Doppler shifts
c. both of the above
d. none of the above
78. Typically, the oldest objects of our Galaxy are
a. open clusters b. globular clusters c. main sequence stars d. comets
79. The outward force keeping a degenerate white dwarf star from collapsing is:
a. degenerate electron "gas" pressure
b. internal pressure from heat
c. its rapid spinning
d. pressure from the outward flow of neutrinos
80. NASA’s Spitzer Space Telescope is:
a. a major ground-based facility
b. a huge telescope to be placed on the moon
c. a small liquid helium cooled infrared observatory that is orbiting the sun
d. an earth-orbiting infrared telescope that has been operating for about a year