Physics 110: Astronomy and Cosmology
Final Exam
Please bubble in the following test code on your answer sheet: 156
1. 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.
2. 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.
3. 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. Matter is being created by supernova explosions.
c. Photons lose
energy as the Universe expands.
d. There is more matter now – nuclear fusion in stars is increasing the matter content of the Universe.
e. Photon energy is constantly converted into matter as the Universe evolves.
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. 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 produce a bright flash of light.
d. they immediately
pass through the core and escape to space.
e. . they form the neutron star.
6. 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.
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 II supernova.
b. The star would eventually become a brown dwarf.
c. The star would
erupt as a type I supernova.
d. The star would eventually become a neutron star.
e. The star would eventually become a black hole.
8. Collisions between galaxies
a. cause large numbers of stars to collide and explode.
b. never occur.
c. trigger supernova explosions.
d. may cause bursts
of star formation.
e. turn ellipticals into spirals.
9. 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.
10. About how many stars are in the Milky Way?
a. several hundred thousand
b. One or two million
c. 200 million
d. 100 billion
e. 10 trillion
11. 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.
12. 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.
13. Hubble’s law tells us
a. the location of the Big Bang.
b. how fast galaxies move through space.
c. how quickly space
is expanding.
d. how quickly the Universe is accelerating.
e. the rate at which gravity slows the Universe
14. The author of The Extravagant Universe
a. joined the high-z
supernova team in the mid-90s, after nearby supernovae were well-characterized.
b. joined a Danish group in seeking supernovae for cosmology in the 80s.
c. joined the Supernova Cosmology Project group in seeking supernovae in the early 90s.
d. single-handedly pioneered supernova cosmology.
e. is a science writer for The New York Times who reported many of the supernova results as they were announced.
15. 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.
16. The presently accepted values for the Hubble constant gives which range of ages for the Universe?
a. 6000 to 8000 years.
b. 1 to 5 billion years.
c. 10 to 20 billion
years.
d. At least 50 billion years.
e. The universe is eternal; it has always existed.
17. Present observational data seem to indicate that the Universe will
a. expand forever.
b. reach static equilibrium.
c. eventually collapse.
18. A galaxy located 3.0 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. 210 km/s.
19. About how hot was the Big Bang when photons were finally able to travel freely through space?
a. 2.73 K
b. 4000 K
c. 10,000 K
d. 15 million K
e. 100 million K
20. What is the meaning of a “marginally bound” 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.
21. 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. any object which
is smaller than its event horizon.
e. the most important type of dark matter.
22. 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.
23. 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. blue stars
e. low mass stars
24. 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.
25. 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 very far and the light gets stretched by the expansion of the Universe while it travels through space..
b. The star or
galaxy is located behind a dust cloud which reddens the light.
c. The star or galaxy is moving away from the Sun.
d. The star or galaxy is very massive and the light loses energy trying to escape.
26. When we observe stars near the center of the Milky Way Galaxy, we detect light that was emitted from those stars about
a. 8 minutes ago.
b. 8 years ago.
c. 25,000 years ago.
d. 25 million years ago.
e. when the galaxy was formed.
27. 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. radar ranging
d. trigonometric parallax using Earth’s orbit
e. the Hubble Law of recession of galaxies
28. The greatest variation in size and mass occurs in which type of galaxy?
a. Quasars
b. Barred spirals
c. Irregulars
d. Ellipticals
e.
29. 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.
30. 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.
31. Suppose the Hubble Constant were measured and found to be half 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.
32. 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 within the Universe.
a. 100%
b. 70%
c. 30%
d. 10%
e. 3%
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. 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.
35. You could best map out the overall spiral structure of our Galaxy by finding
a. smooth, round globular clusters
b. evolved stars like planetary nebulae and RR Lyrae stars
c. high-velocity stars
d. young open
clusters and emission nebulae