WSU ASTR 135 Exam 3
11-17-99
1. Which of the following is not a characteristic of the stars of the disk component of our galaxy?
a. circular orbits
b. randomly inclined orbits
c. higher metal abundance
d. young stars
e. star formation regions
2. Younger stars have more heavy elements because
a. old stars destroy heavy elements as they age.
b. young stars burn their nuclear fuels faster.
c. the heavy elements were made in previous generations of stars.
d. heavy elements haven't had time to settle to the core of these younger stars.
e. all of these
3. Our galaxy is suspected to be surrounded by a galactic corona because the disk of the galaxy
a. rotates faster than expected in its outer region.
b. rotates more slowly than expected in its outer region.
c. rotates faster than expected in its inner region.
d. rotates more slowly than expected in its inner region.
e. is much flatter than expected.
4. The age of the Milky Way galaxy has been estimated to be at least 15 billion years based on
a. 21-cm radiation from H I regions.
b. the rotation curve of the galaxy.
c. the energy produced by Sagittarius A*.
d. the ages of the oldest main-sequence stars in globular clusters.
e. the ages of the youngest main-sequence stars in the disk.
5. A Type II Cepheid has been located in a distant globular cluster with a period of 10 days, what is the star's absolute magnitude?
a. -1
b. 0
c. -4
d. -6
6. How do astronomers explain the existence of spiral structures in many galaxies?
a. The rotation flings out stars and gas from the galactic center.
b. A density wave of gas and star formation traveling around the disk.
c. The spiral arms orbit the galactic center a the same rate as stars.
d. By the Hubble Law.
7. The Sun is located
a. in the galactic center of the Milky Way.
b. in the halo of the Milky Way 8kpc from the galactic center.
c. in the disk of the Milky Way 8kpc from the galactic center.
d. in Sagittarius A*.
8. The mass of the Milky Way is found from
a. the rotation curve.
b. the light curve.
c. the density wave.
d. the Chandrasekhar limit.
9. Spiral arms are sites of
a. globular clusters.
b. star formation.
c. the dark matter halo.
d. radio quiet regions.
10. The chemical composition of the Milky Way is
a. static and never changes.
b. is slowly being converted into hydrogen.
c. is being converted from hydrogen and helium to heavier elements.
d. is impossible to find using spectroscopy.
11. The nuclear bulge of the Milky Way is most similar to
a. the disk.
b. the spiral arms.
c. the density wave.
d. the halo.
12. RR Lyrae and Cepheid stars have variable brightness because
a. they are stable but have binary companions.
b. they rotate and emit beams of synchrotron radiation.
c. they expand and contract.
d. they are exploding stars.
13. A megaparsec is equivalent to
a. 3.26 light-years.
b. 206,265 light years.
c. 206,265 AU.
d. 106 parsecs.
14. Which of the following is not used as a distance indicator?
a. Cepheid variable stars
b. Herbig-Haro objects
c. Supernovae
d. novae
15. A tuning fork diagram is shown below. Which of the labeled figures
represents an E0 galaxy?
a. 1
b. 2
c. 3
d. 4
e. 5
16. ___________ galaxies contain large clouds of gas and dust, both young and old stars, but have no obvious spiral arms or nucleus.
a. Irregular
b. S0
c. E7
d. Sa
e. E0
17. The Milky Way galaxy is part of
a. the Virgo cluster
b. the Large Magellanic Cloud.
c. the Small Magellanic Cloud.
d. the Local Group.
18. The most accurate method of measuring the distance to a nearby galaxy is
a. Cepheid variable stars
b. spectroscopic parallax.
c. stellar parallax.
d. radar
19. Of the following, the one that is the least likely consequence of the collision of two galaxies is
a. a merger of the galaxies
b. distortion of the appearances of the galaxies.
c. collisions of many stars within the galaxies.
d. bursts of star formation within the galaxies.
20. Ring galaxies are the result of
a. smoke and dust.
b. star collisions.
c. nucleosynthesis.
d. galactic collisions.
21. Elliptical galaxies
a. are shaped like pinwheels.
b. contain a lot of dust, gas, and star formation.
c. contain a lot of hot, young, massive stars.
d. contain little gas, dust, and star formation.
22. Which of the following is the Hubble Law?
a. The greater the distance to a galaxy the greater the redshift.
b. The greater the distance to a galaxy the fainter it appears.
c. The more distance the galaxy the younger it appears.
d. Most galaxies belong to a galactic cluster.
23. Why does the Cepheid distance technique have limited usefulness beyond 5 Mpc?
a. Distant galaxies are seen too far in the past.
b. Distant galaxies are too young.
c. Cepheids are too faint to be seen beyond about 5 Mpc.
d. Cepheids do not pulsate beyond 5 Mpc.
24. The presence of a disk and a halo in a spiral galaxy is the result of
a. binary stars.
b. the motions of the stars around the galactic center.
c. planets around stars.
d. the 21-cm line.
25. That the radio lobes radiate synchrotron radiation indicates that
a. high speed electrons are spiraling through a magnetic field.
b. the source of the radio jets must be a black hole.
c. the source of the radio energy is rotating rapidly.
d. the central galaxy must be a giant elliptical galaxy.
26. If the red shifts of quasars arise from the expansion of the universe,
a. a quasar must be very small.
b. a quasar must be within the Local Group.
c. a quasar must be single star with an extremely large mass.
d. a quasar must be very luminous.
27. What was the first evidence that quasars were different from any objects observed?
a. Quasars emitted radio energy like active galaxies, but appeared to be point sources at visible light.
b. Quasars showed significant gravitational lens effects.
c. The spectra of quasars looked like that of an M dwarf.
d. The large red shifts originally indicated that they were orbiting the center of the Milky Way.
28. __________________ is (are) observed when light from a distant quasar travels past a massive galaxy between us and the quasar, and this light is focused to form two or more images of the same quasar.
a. Gravitational waves
b. A blazar
c. The gravitational lens effect
d. A double-lobed radio galaxy
29. Why is the energy source of Seyfert galaxies thought to be extremely compact?
a. Their spectra are non-thermal.
b. Their spectra are just due to stars.
c. They vary in brightness on rapid time scales.
d. They can be seen clearly therefore they are compact.
30. Which of the following is NOT associated with Seyfert galaxies?
a. Small, brilliant central core.
b. Powerful source of infrared radiation.
c. Radio lobes.
d. Powerful source of gamma radiation.
31. The flatness problem and horizon problem
a. are solved if there was a sudden inflation of the universe at time before recombination occurred.
b. show that the universe cannot be described by the steady state theory.
c. show that dark matter must be a small fraction of the total mass of the universe.
d. imply that the universe was once much hotter than it is now.
32. Whether the universe is open, closed or flat depends on the ________ of the universe.
a. luminosity
b. density
c. temperature
d. radius
33. The flatness problems is that
a. the density of the universe is very close to the critical density.
b. the density of the universe is much larger than the critical density.
c. the flat universe would expand forever and we could never measure the density of the universe.
d. the laws of physics may not be different at different times in the history of the universe.
34. During the first moments of the big bang, nuclear fusion reactions made few heavy elements because
a. all heavy nuclei are unstable.
b. no stable nuclei exist with masses of 5 or 8 hydrogen masses.
c. the helium nucleus is unstable.
d. the temperature and density were too low.
35. The largest known structure in the universe:
a. a massive black hole.
b. the Great Wall.
c. the Milky Way galaxy.
d. the Great Attractor.
36. The filamentary distribution of galaxies
a. will be more easily explained when the dark matter mystery is solved.
b. can be modeled in computer simulations.
c. is well represented by the appearance of the Great Wall.
d. all of the above.
e. none of the above.
37. The future of an expanding universe is dependent upon our knowing the
a. rate of the expansion and the amount of matter in the universe.
b. present "size" of the universe (i.e., how "far away" is the Big Bang from us).
c. exact direction in the sky from which the universe first began expanding.
d. age of the universe
38. If the universe was infinitely old, infinitely large, and homogeneous, then
a. the sky should be dark.
b. the sky should be bright.
c. we should see planets.
d. we should see quarks.
39. The universe is
a. centered on the Earth.
b. centered on the Sun.
c. centered on the Milky Way.
d. without a center.
40. The age of the universe should be
a. younger than the oldest stars.
b. older than the oldest stars.
c. younger than the youngest stars.
d. infinitely old.
41. Pair production can occur if
a. The energy of two photons is greater than the combined mass-energy of a particle-anti-particle pair.
b. Only virtual particles are produced.
c. Photons are at the event horizon of a black hole.
d. pairs of particle collide.
42. How hot was the universe at time zero?
a. 6,000 K
b. 6 million K
c. 500 K
d. Probably infinitely hot.
43. The redshift of galaxies in the universe is correctly interpreted as
a. Doppler shift
b. Aging of starlight
c. Space itself expanding with time
d. Different temperatures in the universe
44. In which cosmological model will the universe keep expanding forever?
a. Open
b. Closed
c. Bumpy
d. Spiral
45. Homogeneity and isotropy are the assumptions in the
a. Hubble Law
b. Olber's paradox
c. The steady state model
d. The cosmological principle
46. The Hubble constant suggests an age of the universe of
a. about 500 million years
b. about 5 billion years
c. about 13 billion years
d. about 5 trillion years
47. Because all galaxies are redshifted implies:
a. We are at the center of the universe.
b. The universe is expanding.
c. The sky is dark at night.
d. The universe is shrinking.
48. The look-back time of an object is directly related to its
a. distance
b. variability
c. luminosity
d. size
49. According to the Big Bang, during the very earliest moments of the universe, the first radiation was
a. gamma rays
b. infrared and radio waves
c. neutrinos
d. hydrogen
50. Which of the following statements is FALSE?
a. Hubble's law suggests that galaxies are not moving away, but that space-time is expanding
b. The origin of the universe cannot be approached by modern science, since there is no way to explain where the universe was before it came into existence
c. The Big Bang occurred everywhere we look in the sky. There is no particular direction in which the Big Bang occurred
d. the ultimate fate of matter in a open, ever-expanding universe is to become black holes, neutron stars, and black dwarfs