Exam 3 Spring 2000 Practice Test 2

  1. A major discovery made by Shapley using RR Lyrae stars and globular clusters established
    1. That the spiral nebulae are actually galaxies outside the milky way.
    2. That the spiral arms are regions of star formation.
    3. The size of the galaxy and the sun's position in it.
    4. That globular clusters lie outside the milky way at large distances.
  2. What type of matter is observed using radio telescopes in the mapping of the galactic structure?
    1. Hydrogen gas and the carbon monoxide molecule
    2. Ionized hydrogen and the water molecule
    3. Hydrogen and helium gas and the carbon dioxide molecule
    4. Hydrogen and helium gas and the water molecule
  3. Where is active star formation most often found in the galaxy?
    1. Halo
    2. Disk
    3. Galactic bulge
    4. Spiral arms
  4. What events may trigger new star formation in a spiral arm?
    1. Compression from a density wave
    2. Shock waves from emission nebulae
    3. Shock waves from supernovae
    4. All of these
  5. Which of the following properties of elliptical galaxies is also shared with spiral galaxies?
    1. No significant gas or dust
    2. Lack of a disk
    3. Contains old stars
    4. Large range in size and number of stars
  6. Hubble's law relates which two observed properties of a galaxy?
    1. Rotation and luminosity
    2. Distance and recessional velocity
    3. Peak luminosity and distance
    4. Mass and luminosity
  7. Once Hubble's law is established, what single observation is needed of a galaxy in order to determine its distance?
    1. Luminosity
    2. Line broadening
    3. Mass
    4. Recessional velocity
  8. What is observed that connects radio emissions in the galactic nucleus with the emissions in the halo or radio lobes?
    1. There is no connection other than that these emissions come from the same galaxy.
    2. There is a jet of matter coming out of the nucleus, which often points towards the lobes.
    3. Variations in brightness of the nucleus occur at the same time as variations in the lobes or halo.
    4. Both produce the same type of radiation.
  9. Specifically, what produces the intense radiation, jets, and other features of active galaxies?
    1. Supermassive black holes
    2. Very large star clusters
    3. Galactic collisions
    4. Accretion disks which surround supermassive black holes
  10. Which of the following properties of quasars is common to all quasars without exception?
    1. High redshift
    2. Completely stellar in appearance
    3. Emission of radio radiation
    4. Found in clusters of galaxies
  11. What is the strongest piece of evidence suggesting that quasars represent an early stage of galaxy formation?
    1. They are all surrounded by young galaxies.
    2. Nonthermal radiation is emitted only by very young galaxies.
    3. They are all distant.
    4. They are star-like in appearance.
  12. How does the age of the universe depend on the Hubble constant?
    1. It is proportional to it.
    2. It depends on the square of it.
    3. It is inversely proportional to it.
    4. It is proportional to the inverse square of it.
  13. Which of the following is the correct interpretation of the Hubble law?
    1. As galaxies move outward, they are replaced with new matter created to take its place.
    2. The farther away a galaxy is from us, the faster it is moving away, because of the big bang.
    3. Galaxies are not moving through space, it is space that is expanding over time.
    4. Galaxies are stationary but time continues to change, giving the appearance of motion.
  14. Where did the big bang occur?
    1. Here
    2. There
    3. Everywhere
    4. At what we now call the edge of the universe
    5. At the locations of the quasars
  15. What is the explanation for the high redshifts observed in distant objects?
    1. They are rapidly moving away from us.
    2. Their light has been gravitationally redshifted.
    3. Their light has lost energy over time while traveling this distance.
    4. In the time it took their light to reach us, the universe expanded and, thus, their wavelengths.
  16. What is the origin of the cosmic microwave background?
    1. Light remaining from the big bang
    2. The combined radiation of all objects too distant to see individually
    3. Billions and billions of stars in the universe
    4. The total of all the synchrotron sources
  17. By the end of the nuclear epoch, some 1000 seconds after the big bang, the matter of the universe was composed of 25 percent _____ .
    1. Hydrogen
    2. Helium
    3. Deuterium
    4. Carbon
  18. What purpose or role was played by dark matter in the early universe?
    1. Its density fluctuations determined the overall large-scale structure of the universe.
    2. It gave rise to the period of inflation.
    3. Microwave background radiation is the result of dark matter decoupling from baryonic matter.
    4. It limited the nucleosynthesis of heavy elements during the big bang.
  19. What type of spectrum is the cosmic microwave background?
    1. Thermal radiation
    2. Emission line
    3. Absorption line
    4. Synchrotron
  20. What perception of the Milky Way Galaxy did astronomers have in the early part of this century?
    1. They believed that the Earth rested inside concentric spheres, with the Milky Way stars fixed to the outermost sphere.
    2. They believed that the Milky Way was on one of billions of galaxies in the Universe.
    3. They believed that the Milky Way was the entire universe.
    4. They believed that, because the Sun was at the center of the Milky Way, it was impossible to see the rest of the Universe.
  21. The location of the center of the Galaxy is determined by observations of
    1. Cepheids
    2. Globular Clusters
    3. The spiral arms
    4. A visually bright massive object around which all objects in the Galaxy move.
  22. Which is the correct description of the Sun's location within the Milky Way?
    1. At the outer edge of the galactic bulge but in the plane of the disk.
    2. In the disk, but at its very outer edge.
    3. Above the disk and about 1/3 the of the galactic radius from the center.
    4. In the disk and about 2/3 of a galactic radius from the center.
  23. The object located at the center of the Galaxy is believed to be a
    1. large cluster of stars
    2. an enormous emission nebula
    3. supermassive black hole
    4. quasar
    5. massive star formation region
  24. What property is common to almost all spiral galaxies
    1. Ongoing star formation
    2. The disk, bulge, and halo
    3. Abundant interstellar gas
    4. All of the above.
    5. None of the above.
  25. Which of the following is the Hubble Law?
    1. The greater the distance to a galaxy, the greater its redshift.
    2. The greater the distance to a galaxy, the fainter it is.
    3. The more distant a galaxy is, the younger it appears.
    4. Most galaxies belong to a cluster; most clusters, to a super cluster
  26. What does the Hubble Law measure?
    1. The rate of expansion of the Universe.
    2. How galaxies are distributed in the Universe.
    3. How light gets fainter with increasing distance.
    4. Light travels at a finite speed; we experience "look-back" time.
  27. A galaxy is at a distance of one billion light years. Which of the following is true?
    1. We see the galaxy the way it will be in one billion years.
    2. We see the galaxy the way it was one billion years ago.
    3. We see the galaxy the way it was when the Universe was one billion years old.
    4. We see what our galaxy will be like in one billion years.
  28. Why are supermassive elliptical galaxies often found at the cores of rich galaxy clusters?
    1. Most of the matter forming the cluster fell into the center.
    2. Such a large galaxy attracted smaller galaxies around it to form a cluster.
    3. Large galaxies, passing a cluster, get captured into the center.
    4. The are the result of numerous galactic mergers--cannibalism on the largest scale.
  29. The look-back time of an object is directly related to its
    1. distance.
    2. variability.
    3. luminosity.
    4. size.
  30. Why do some quasars and galaxies have redshifts greater than 1?
    1. They are very distant.
    2. They are moving away from us faster than the speed of light.
    3. Our technology is not advanced enough to accurately measure these redshifts.
    4. They are actually moving towards us.
  31. Because we see the light from distant galaxies redshifted, we know that
    1. we are at the center of the Universe.
    2. the Universe is expanding.
    3. the sky must be filled with galaxies.
    4. all of the above.
  32. The cosmic microwave background is important mostly because
    1. its detection represented a major technological advance.
    2. it confirmed a major prediction made by the Big Bang theory.
    3. it showed that the Universe is open.
    4. it showed that the Universe is closed.
  33. The redshift of galaxies in the Universe is correctly interpreted as
    1. a Doppler shift due to the motions of the galaxies through space.
    2. an "aging" of the light.
    3. space itself expanding with time, stretching the wavelengths from the light
    4. the difference in temperatures of distant and nearby galaxies.
  34. Why didn't an abundance of elements heavier than helium form in the early universe?
    1. The expansion of the Universe cause the temperature and density to drop too low for fusion to occur.
    2. Heavier elements did form, but they didn't survive the process that made the earliest stars and galaxies.
    3. The laws of physics prohibit the formation of elements heavier than helium, except in stars
    4. All of the above.
    5. None of the above.
  35. Currently, most of the mass of the Universe is believed to consist of:
    1. protons and neutrons.
    2. dark matter.
    3. the stars
    4. black holes.
  36. An astronomer needs to measure the distance to a globular cluster of stars that is part of the Milky Way. What method should she try to use?
    1. measure the parallax of the cluster.
    2. count the number of O and B type stars in the cluster.
    3. look for flickering x-rays coming from black holes in binary systems
    4. measure the redshift of the cluster
    5. find an RR Lyrae variable star in the cluster.
  37. Our Milky Way galaxy is what type of galaxy?
    1. spiral (barred spiral)
    2. elliptical
    3. dwarf elliptical (most common type in local group)
    4. irregular
    5. none of the above
  38. Where should we look for the youngest stars in the Milky Way?
    1. in the halo.
    2. wherever there is dark matter
    3. in the spiral arms of the disk
    4. in the nucleus of the Galaxy
    5. in all parts of the Galaxy.
  39. Globular clusters orbit the center of the Milky Way in very elliptical orbits. At any given time, where would we expect to find most of these clusters?
    1. In the bulge where it is dense.
    2. In the halo, because that's where they spend the most time.
    3. In random locations in the disk and bulge.
    4. Being eaten by the supermassive black hole at the center of the Galaxy.
  40. One of the most important observations in the history of astronomy was the one made by Edwin Hubble (about 1920) that established that there are other galaxies, quite removed from the Milky Way. How did Hubble show this?
    1. By winning the debate with Drs. Shapley, Curtis, and Einstein.
    2. By observing a supernova explosion in a nearby galaxy, using it as a "standard candle."
    3. By observing a Cepheid variable in the Andromeda galaxy and using it to get the distance.
    4. By measuring the distances to many globular clusters using RR Lyrae variables.
  41. Which type of galaxy is observed to contain almost all old stars?
    1. Spiral
    2. Barred spiral
    3. Elliptical
    4. Irregular
    5. All of the above contain mostly older stars.
  42. What method would astronomers use to find the distance to a galaxy so far away that individual stars are impossible to make out (resolve)?
    1. parallax
    2. Cepheid variables
    3. using the x-ray emission from the entire galaxy
    4. finding the redshift and using Hubble's Law
    5. the turnoff point of the main sequence on an H-R diagram
  43. Edwin Hubble was able to show that (with the exception of our nearest neighbors) the farther a galaxy is from us, the
    1. brighter it looks.
    2. bluer its color.
    3. the later in its life we are seeing it.
    4. the larger its halo is.
    5. the faster it is moving away from us.
  44. The Andromeda Galaxy, our nearest spiral neighbor, has spectral lines that show a blue shift. From this we may conclude that,
    1. the Universe has stopped expanding.
    2. this particular galaxy is moving toward us.
    3. this galaxy has merged with the Milky Way.
    4. this particular galaxy is moving away from us.
    5. this galaxy has an unusual number of very bright, hot O- and B-type stars in it.
  45. According to Hubble's Law, if galaxy B is three times farther away from us as galaxy A, then galaxy B will
    1. move toward us three times faster than A
    2. move away from us nine times faster than A.
    3. move away from us three times faster than A
    4. move toward us nine times faster than A.
    5. move away from us at about the same speed as A.
  46. Which of the following statements about the implications of Hubble's Law is FALSE?
    1. the law implies that the whole universe must be expanding.
    2. the law can be used to measure distances to remote galaxies for which we can measure a redshift.
    3. the law does NOT require us to be at the center of the expanding universe.
    4. if you were observing the universe from a distant galaxy, you would NOT see all the galaxies (except those in your own group) moving away from YOU
    5. although galaxies move away from each other, they themselves are not expanding in size.
  47. A distant quasar shows a large redshift, one so large, in fact, that the features we now see in the visible-light region of the spectrum would be invisible to us, were it not for the redshift. What band of the electromagnetic spectrum were these features most likely in, before the spectrum was redshifted?
    1. radio
    2. infrared
    3. ultraviolet
    4. microwaves
    5. visible
  48. What do the surveys of the three-dimensional distribution of groups of galaxies reveal about how groups and clusters of galaxies are organized?
    1. The groups are distributed completely evenly, with no structure evident.
    2. The groups make a huge spiral structure that resembles the Milky Way, but is much, much larger.
    3. The groups are organized into huge spherical "lumps."
    4. The groups are organized into huge filaments with great voids between them.
    5. Our current day technology has failed us in this case.
  49. Astronomers can now report that active star formation was going on at a time when the Universe was only a few billion years old. When astronomers make such a statement, how can they know what was happening back then?
    1. They look at open clusters in our galaxy and extrapolate to the past.
    2. They look at radio emission from quasars.
    3. They look at the way galaxy redshifts change with time.
    4. They examine the spectra of extremely high-redshift galaxies.
  50. Einstein included a cosmological constant in his equations describing the Universe because
    1. his mathematics failed him in this case.
    2. he had corresponded with Hubble and knew about Hubble's Law.
    3. he could not bring himself to imagine a universe in motion
    4. he believed the Universe was contracting.
    5. None of the above.
  51. If the Hubble constant turns out to be LARGER than we have thought in the past, it means that
    1. the age of the Universe is older than we thought.
    2. the age of the Universe is younger than we thought.
    3. the galaxies are moving apart more slowly than we thought.
    4. the time that has passed since the Big Bang is greater than we thought.
    5. None of the above.
  52. Today, we believe that only a small number of elements were actually formed during the Big Bang. Which of the following was NOT one of these?
    1. hydrogen
    2. carbon
    3. lithium
    4. helium
    5. deuterium
  53. What is the strongest force in the Universe?
    1. gravity
    2. electromagnetic
    3. weak nuclear
    4. strong nuclear
    5. UW women's softball team (no matter what)
  54. If you wanted to find a type of atom in your little finger that has been in its present form (has been the same element) since the beginning of the Universe, which element should you look for?
    1. hydrogen
    2. carbon
    3. iron
    4. oxygen
    5. deuterium
  55. Galaxies are
    1. groups of billions of stars.
    2. generally invisible with today's telescopes.
    3. humongous dust clouds in space.
    4. typically 10 to 100 times larger than the solar system.
    5. basically indescribable.
  56. Open clusters of stars are found
    1. primarily within the galactic disk.
    2. primarily in the halo.
    3. primarily in the bulge.
    4. about equally in the disk and in the halo.
  57. Cepheid variables are important to us in calculating
    1. distances to galaxies
    2. the compositions of stars.
    3. the compositions of the interstellar medium.
    4. the ages of the galaxies.
    5. the temperatures of stars.
  58. Why is observation of distant parts of the Galaxy limited in the visible region?
    1. Interstellar dust blocks visible light.
    2. The redshift of distant stars makes them difficult to detect.
    3. The opacity of the atmosphere blocks most types of radiation.
    4. Relative motion of the spiral arms makes them difficult to detect.
  59. According to the density wave theory of the spiral arms,
    1. there is about the same number density of stars between the spiral arms as in them.
    2. the number density of stars is much greater between the spiral arms than in them.
    3. the number density of stars is much less between the spiral arms than in them.
    4. the density wave theory predicts nothing about the number density of stars.
  60. The look-back time of an object is
    1. how long light from the object takes to reach Earth
    2. numerically equal to the distance to the object in light years.
    3. larger for more distant objects
    4. All of the above.
    5. None of the above.
  61. If the most recent data are correct, the Universe will
    1. expand forever, never stopping
    2. stop its expansion, contract, and "bounce"
    3. stop its expansion but never contract
    4. remain in its steady state
  62. What EVIDENCE indicates that an explosion took place at the beginning of the Universe?
    1. the density of matter in the Universe
    2. the low intensity radiation from all directions.
    3. the Big Bang theory.
    4. the steady state theory.
    5. the existence of massive-star supernovae.
  63. Without irregularities in the early universe,
    1. the Big Bang theory would be wrong.
    2. the galaxies wouldn't exist
    3. you wouldn't be taking this class.
    4. B and C, but not A
    5. None of the above

1 C; 2 A; 3 B; 4 D; 5 C; 6 B; 7 D; 8 B; 9 D; 10 A; 11 C; 12 C; 13 C; 14 C; 15 D; 16 A; 17 B; 18 A; 19 A; 20 C; 21 B; 22 D; 23 C; 24 D; 25 A; 26 A; 27 B; 28 D; 29 A; 30 A; 31 B; 32 B; 33 C; 34 A; 35 B; 36 E; 37 A; 38 C; 39 B; 40 C; 41 C; 42 D; 43 E; 44 B; 45 C; 46 D; 47 C; 48 D; 49 D; 50 C; 51 B; 52 B; 53 D; 54 A; 55 A; 56 A; 57 A; 58 A; 59 A; 60 D; 61 A; 62 B; 63 D.