ASTR 3

  1. All G-type stars have approximately the same
    temperature
  2. **Most methods for determining the distances to stars which are too far away for the use of the trigonometric parallax method are based on
    comparison of a star's apparent magnitude with an estimate of its absolute magnitude
  3. **Which of the following definitely does not agree with present theories of stellar evolution?
    [the misconception that] the more massive stars have the longest main sequence lifetimes.
  4. What is Cygnus X-1?
    a leading candidate for being a black hole
  5. The Doppler effect enables us to measure the ____ of a star.
    radial velocity
  6. Which star has the longest main-sequence life expectancy?
    [smallest number]
  7. how to find relative magnitude of stars
    Logarithmic scale of 2.51, starting from sixth magnitude and going down
  8. **Which two ingredients are needed to make an emission nebula?
    Hot stars and interstellar gas
  9. What is the likely final fate of a star whose mass is 1.1 solar masses after it has finished its main sequence life?
    It will shrink and become a white dwarf
  10. What is the singularity that is often mentioned when talking about a black hole?
    A point of infinite density
  11. A mass of material is condensing into a star. If this "protostar" contains one half the mass of the Sun, when it finally contracts to the main sequence stage it will most likely be of which spectral type?
    K
  12. When the light of a star is dimmed by the effects of intervening dust, we are likely to __________ the distance to the star.
    overestimate
  13. **The absolute magnitude of a star is defined to be the apparent magnitude that the star would have if it were at a standard distance of __ parsec(s).
    10
  14. The “helium flash” occurs at what stage of stellar evolution?
    Low mass stars as they become red giants
  15. Because of precession on the Earth, the
    celestial poles gradually change position among the stars.
  16. 10,000 parsecs = ___ light years
    32,600 light years
  17. If considerable interstellar material was located between the observer and the star, how would the determined distance be affected?
    The distance determination would be overestimated.
  18. **Which kind of process, as a net result, supplies the energy for the stars?
    Hydrogen is converted to helium through fusion.
  19. The Crab nebula is material blown off a ____(1)____, which was observed by the Chinese in AD 1054. At its center we now observe a ____(2)____.
    • Supernova;
    • Pulsar
  20. Which spectral types are the hottest?
    O and B
  21. Which spectral types are the coolest?
    K and M
  22. Which spectral type has the strongest hydrogen lines?
    A
  23. Which spectral type has the strongest molecular bands?
    M
  24. Which spectral types are red?
    Cool stars - so K and M
  25. Which of these is not a possible final stage of stellar evolution?
    T Tauri stage
  26. **Name the second most abundant element in typical stars.
    Helium
  27. **Observation of the shift of a star’s spectrum toward the red or blue enables us to determine the star’s
    radial velocity
  28. What characteristic is the same for all stars in a star cluster?
    age
  29. Which kind of star has the greatest average density?
    Neutron star
  30. Which of these features is NOT characteristic of nuclear fusion?
    Very large, radioactive nuclei are produced as waste products.
  31. The early experiments designed to search for solar neutrinos showed
    probable difficulty in our theories of stellar interiors.
  32. **Suppose you are at the equator, which has a latitude of 0°. The altitude of the north celestial pole as seen from your position is
    • The altitude of the north celestial pole is always the same as your latitude on the surface of the Earth.
  33. Which is NOT a characteristic of a red giant?
    Iron being formed into heavier elements
  34. Stars at the left-hand end of the main sequence have which one of these?
    Large masses
  35. A good way to determine the distance of a distant star cluster is to
    **compare its H-R diagram with a standard H-R diagram.
  36. **Which of these is the greatest distance?
    anything with parsecs
  37. **Most methods for determining the distances to stars which are too far away for the use of the trigonometric parallax method are based on ________.
    comparing a star's apparent magnitude and estimated absolute magnitude.
  38. What effect does dust have on visible light passing through it?
    It dims and reddens it.
  39. The center of our galaxy is located in the direction of the constellation of
    Orion.
  40. What is the 21-cm line?
    A radio wave produced by neutral hydrogen
  41. Which clusters are generally located near the plane of the Milky Way?
    Open clusters
  42. The chief cause of the differences observed among the various types of stellar spectra is the result of differences in ______ from star to star.
    surface temperature
  43. The fact that the Sun is far removed from the center of our galaxy was first conclusively demonstrated by a study of the distribution in space of
    globular clusters.
  44. Which of the following is almost never found in our galaxy's halo?
    Emission nebulae
  45. The Magellanic clouds seen in the southern hemisphere are classic examples of
    Irregular galaxies.
  46. The Hubble Law allows astronomers to estimate the age of the Universe. Currently, the best estimate for this age from the Hubble Law and the Hubble Constant is about
    14 years
  47. When describing galactic structure, 21-cm radiation refers to
    A radio wave produced by neutral hydrogen
  48. What does the Hubble Law measure?
    The rate of expansion of the Universe
  49. **The distances to the nearer galaxies like M31 in Andromeda are based primarily on observations of the periods of the in these nearer galaxies.
    Cepheid variable stars
  50. Provo, Utah, is at 40° north latitude. How often is the Sun directly overhead at noon in Provo?
    never
  51. Which clusters are generally located in the halo of the Milky Way?
    Globular
  52. Recent data from distant supernovae indicate that
    the expansion of the Universe is speeding up.
  53. **What does the Hubble Law measure?
    The rate of expansion of the Universe
  54. Which of the following distance measurement methods (which do not include the Hubble relation) extends furthest into the cosmos?
    Observations of type Ia supernovae
  55. What do we believe to be the central engine for an active galaxy?
    A supermassive black hole
  56. A quasar is thought to be
    a very luminous active galaxy at a very large distance from our galaxy.
  57. The most distant objects that we can observe appear to be
    quasars
  58. The distance to the bright quasar 3C 273 is estimated to be about
    2 billion light-years
  59. At the present time, the value of the Hubble constant is
    thought to have a value very close to 70 km/s/Mpc.
  60. **Recent data from distant supernovae indicate that
    the expansion of the Universe is speeding up.
  61. In cosmology, the phrase “critical density” refers to the
    density needed to produce precisely flat space.
  62. In high-energy physics, when two gamma-ray photons meet, they can
    disappear, creating a particle-antiparticle pair.
  63. In cosmology, what is the “inflationary epoch”?
    A short period of extremely rapid expansion when the Universe was very young
  64. One wavelength that would be appropriate to monitor in SETI research would be
    21 cm.
  65. The “water hole,” a region of the radio spectrum chosen for searches for signals from intelligent life because galactic and Earth-based noise and atmospheric absorption are at a minimum, is so named because
    two astronomically important wavelengths, the 21-cm line of H and a line from the hydroxyl radical OH, are in this region (the letters H and OH signifying water).
  66. Isotropy and homogeneity, taken as assumptions regarding the structure and evolution of the Universe, are known as
    the Cosmological Principle.
  67. The spectrum of the cosmic microwave background shows a constant and nearly isotropic blackbody temperature of
    2.7 K.
  68. The Drake equation attempts to predict the
    number of technologically advanced civilizations in our Galaxy.
  69. Which elements were created during the Big Bang?
    Hydrogen, helium, lithium, and beryllium
  70. Which object is most likely to host planets supporting life as we know it?
    Low-mass main sequence stars
Author
katiedr96
ID
340268
Card Set
ASTR 3
Description
for ASTR
Updated