Physics 110: Astronomy and Cosmology
Final Exam
May 10, 2005
Please bubble in the following test code on your answer sheet: 151
1. The author of The Extravagant Universe
a. joined a Danish group in seeking supernovae for cosmology in the 80s.
b. joined the Supernova Cosmology Project group in seeking supernovae in the early 90s.
c. joined the high-z supernova team in the mid-90s, after nearby supernovae were well-characterized.
d. is a science writer for The New York Times who reported many of the supernova results as they were announced.
e. single-handedly pioneered supernova cosmology.
2. The surprising result discovered by the two supernova cosmology teams is
a. The Universe has already begun to re-collapse.
b. The Universe consists primarily of dark matter.
c. The Universe is expanding faster now than it was in the past.
d. The Universe is filled with weird dust.
e. Wo = 1.
3. Hubble’s law tells us
a. how fast galaxies move through space.
b. the location of the Big Bang.
c. how quickly space is expanding.
d. how quickly the Universe is accelerating.
e. the rate at which gravity slows the Universe
4. Nearly all of the elements found in our environment were formed inside stars, except for
a. Iron and nickel.
b. Oxygen and carbon.
c. Silver and technetium.
d. Hydrogen and helium.
e. Neon and argon.
5. The heaviest elements found in nature are created by
a. Neutron capture.
b. The triple alpha process.
c. The alpha process.
d. The CNO cycle.
e. The decay of radioactive iron.
6. When a stellar iron core collapses, large numbers of neutrinos are formed, then
a. they are captured to form light elements.
b. they are captured to form heavy elements.
c. they form the neutron star.
d. they immediately pass through the core and escape to space.
e. they produce a bright flash of light.
7. What would happen if mass is continually added to a 1.4 solar mass white dwarf?
a. The star would erupt as a type I supernova.
b. The star would eventually become a black hole.
c. The star would erupt as a type II supernova.
d. The star would eventually become a neutron star.
e. The star would eventually become a brown dwarf.
8. About how many stars are in the Milky Way?
a. 200 million
b. several hundred thousand
c. One or two million
d. 100 billion
e. 10 trillion
9. Collisions between galaxies
a. never occur.
b. may cause bursts of star formation.
c. turn ellipticals into spirals.
d. cause large numbers of stars to collide and explode.
e. trigger supernova explosions.
10. A galaxy located 2 million parsecs away from the Milky Way would appear to be moving away from us at
a. 35 km/s.
b. 50 km/s.
c. 70 km/s.
d. 140 km/s.
e. 528 km/s.
11. Star formation is most vigorous in
a. giant elliptical galaxies.
b. halos of spiral galaxies.
c. disks of spiral galaxies.
d. globular clusters.
e. dwarf elliptical galaxies.
12. Based on galactic rotation curves and cluster dynamics, we think dark matter
a. is best detected by X-rays in intra-cluster gas clouds.
b. comprises about 90% of the entire mass of the Universe.
c. has no effect on the visible Universe.
d. is a very minor component of the total mass of the Universe.
e. exists in sufficient quantities that Wm = 1.
13. What is the most likely source of energy for active galaxies and quasars?
a. Large clusters of very massive, luminous stars.
b. Accretion onto a supermassive black hole.
c. Numerous supernovae from rapid star formation in young galaxies.
d. A single supermassive, superluminous star.
e. Energy released by primordial nucleosynthesis.
14. The fact that quasars are located at cosmological distances yet appear like ordinary faint stars means
a. they must be very small.
b. they are the brightest stars ever observed.
c. they must be very large.
d. they are intrinsically quite faint.
e. they must be producing very large quantities of energy.
15. The redshift of galaxies in the Universe is correctly interpreted as:
a. an “aging” of the light
b. space itself is expanding with time; the photons get stretched as they travel.
c. a Doppler shift due to the motions of the galaxies through space.
d. The difference in temperatures of distant a nearby galaxies
e. gravitational redshift due to the stronger gravity of more distant galaxies.
16. The presently accepted values for the Hubble constant gives which range of ages for the Universe?
a. At least 50 billion years.
b. The universe is eternal; it has always existed.
c. 1 to 5 billion years.
d. 6000 to 8000 years.
e. 10 to 20 billion years.
17. What is the meaning of a “closed” Universe?
a. The Universe will someday stop expanding and start to collapse.
b. The Universe will stop expanding in an infinite amount of time.
c. The Universe will expand forever.
d. The Universe is in a steady-state.
e. The expansion of the Universe is accelerating.
18. Present observational data seem to indicate that the Universe will
a. eventually collapse.
b. reach static equilibrium.
c. expand forever.
19. Currently, most of the mass of the Universe is believed to consist of
a. stars.
b. ordinary matter.
c. black holes.
d. non-ordinary dark matter.
e. neutrinos.
20. Why didn’t an abundance of elements heavier than helium form in the early universe?
a. The expansion caused the temperature and density to drop too low for fusion past helium.
b. Heavier elements did form, but they didn’t survive the making of the first stars and galaxies.
c. The laws of physics prohibit the formation of elements heavier than helium, except in the confined environments of stellar interiors.
d. Heavier elements did form and quick condensed into dust.
e. Heavier elements did form, and there is ample evidence for them in the Universe today.
21. About how hot was the Big Bang when photons were finally able to travel freely through space?
a. 15 million K
b. 100 million K
c. 4000 K
d. 10,000 K
e. 2.73 K
22. Chemical elements heavier than iron are created primarily by the buildup of
a. colliding massive subatomic particles in the Big Bang.
b. neutrons in atomic nuclei during supernova explosions.
c. proton decay reactions in empty space.
d. stable nuclear fusion in the cores of massive stars.
e. neutrinos in the center of the Sun.
23. Frequently, astronomers find that the absorption lines in a spectrum are “redshifted,” meaning that they appear at longer wavelengths than they do in the laboratory. Which of these is NOT a reason why the radiation from a star or galaxy might appear redshifted?
a. The star or galaxy is moving away from the Sun.
b. The star or galaxy is very massive and the light loses energy trying to escape.
c. The star or galaxy is very far and the light gets stretched by the expansion of the Universe while it travels through space.
d. The star or galaxy is located behind a dust cloud which reddens the light.
24. A black hole is best defined as
a. a star which sucks all matter into itself.
b. a window into another Universe.
c. the final result of all stellar evolution.
d. the most important type of dark matter.
e. any object which is smaller than its event horizon.
25. When we observe stars near the center of the Milky Way Galaxy, we detect light that was emitted from those stars about
a. 25 million years ago.
b. 25,000 years ago.
c. 8 years ago.
d. 8 minutes ago.
e. when the galaxy was formed.
26. You are asked to determine an accurate distance to the Andromeda Galaxy. Choose the best technique below.
a. Doppler shift of spectral lines
b. period-luminosity law for Cepheid variables within Andromeda
c. the Hubble Law of recession of galaxies
d. trigonometric parallax using Earth’s orbit
e. radar ranging
27. When we look at the CMB, we are seeing
a. the instant of the Big Bang.
b. 3 minutes after the Big Bang, when helium formed.
c. a few thousand years after the Big Bang when matter began to dominate over radiation.
d. a few hundreds of thousands of years after the Big Bang when atoms formed.
e. the epoch of quasars.
28. Suppose the Hubble Constant were measured and found to be twice as large as it is now believed to be. The implied maximum age of the Universe in a Big Bang model would be
a. halved.
b. the same.
c. doubled.
d. squared.
29. Current cosmological results suggest that “normal” matter that is made up of protons, neutrons, and electrons (like us!) makes up __________ of the total amount of matter and dark energy within the Universe.
a. 3%
b. 10%
c. 30%
d. 70%
e. 100%
30. What are X-ray bursters?
a. They are rapidly rotating black holes.
b. They are neutron stars on which accreted matter builds up, then explodes in a violent nuclear reaction.
c. They are stars that explode as supernovae, emitting bursts of gamma-rays in the process.
d. They are violet energy sources known to lie at the heart of the Milky Way.
e. They are white dwarfs on which accreted matter builds up, then explodes in a violent nuclear reaction.
31. Which of the following is not found in the Galaxy’s halo?
a. stars with random, three-dimensional orbits
b. globular clusters
c. old stars
d. emission nebulae
e. low mass stars
32. In the early Universe, radiation played a much bigger role than it does today. Why does the density of radiation energy (e.g. photons) decrease faster than the density of matter over the evolution of the Universe?
a. There were more photons in the past – every time we “see” a photon, we destroy it.
b. There is more matter now – nuclear fusion in stars is increasing the matter content of the Universe.
c. Photons lose energy as the Universe expands.
d. Photon energy is constantly converted into matter as the Universe evolves.
e. Matter is being created by supernova explosions.
33. What is one of the differences between Cepheid variables and RR Lyrae variables?
a. Cepheids are higher luminosity stars than RR Lyrae variables, and have longer periods.
b. RR Lyrae variables pulsate irregularly as compared to Cepheids which are very regular.
c. Cepheids vary because they pulsate; RR Lyrae variables vary because they are binaries
d. All Cepheids have the same luminosity, while RR Lyrae stars vary greatly in brightness.
34. You could best map out the overall spiral structure of our Galaxy by finding
a. young open clusters and neutral atomic hydrogen gas.
b. evolved stars like planetary nebulae and RR Lyrae stars
c. smooth, round globular clusters
d. high-velocity stars
35. The greatest variation in size and mass occurs in which type of galaxy?
a. Barred spirals
b. Ellipticals
c. Irregulars
d. Normal spirals
e. Quasars