AST 1002 Final

Card Set Information

Author:
Anonymous
ID:
122208
Filename:
AST 1002 Final
Updated:
2011-12-09 13:15:06
Tags:
astronomy final
Folders:

Description:
astronomy final
Show Answers:

Home > Flashcards > Print Preview

The flashcards below were created by user Anonymous on FreezingBlue Flashcards. What would you like to do?


  1. 1) Our Sun will end its life in
    a planetary nebula and become a white dwarf.
  2. 2) At approximately what temperature can helium fusion occur?
    100 million K
  3. 3) What prevents a white dwarf from having a mass greater than the white dwarf limit (or Chandrasekhar limit)?
    Electron degeneracy pressure depends on the speeds of electrons, and as a white dwarf's mass approaches the white dwarf limit, its electron speeds are already approaching the speed of light.
  4. 4) A teaspoonful of white dwarf material on Earth would weigh
    a few tons.
  5. 5) Compared to the star it evolved from, a white dwarf is
    hotter and dimmer.
  6. 6) Which element has the lowest mass per nuclear particle and therefore cannot release energy by either fusion or fission?
    iron
  7. 7) What do we mean by the singularity of a black hole?
    It is the center of the black hole, a place of infinite density where the known laws of physics cannot describe the conditions.
  8. 9) What happens after a helium flash?
    The core quickly heats up and expands.
  9. 10) In the end, the remaining core of this star will be left behind as
    a white dwarf made primarily of carbon and oxygen.
  10. 11) Neutron stars are
    the densest objects that we can observe in the universe.
  11. 12) What type of star is our Sun?
    low-mass star
  12. 13) After a supernova event, what is left behind?
    either a neutron star or a black hole
  13. 14) Based on current understanding, the minimum mass of a black hole that forms during a massive-star supernova is roughly
    3 solar masses.
  14. 15) Why is Supernova 1987A particularly important to astronomers?
    It was the nearest supernova detected in nearly 400 years.
  15. 16) What is a helium flash?
    the sudden onset of helium fusion in the core of a low-mass star
  16. 17) Why is iron significant to understanding how a supernova occurs?
    Iron cannot release energy by either fission or fusion, so a star with an iron core has no way to generate additional energy to counteract the crush of gravity.
  17. 18) Why does a star grow larger after it exhausts its core hydrogen?
    Hydrogen fusion in a shell outside the core generates enough thermal pressure to push the upper layers outward.
  18. 19) A white dwarf is
    what most stars become when they die.
  19. 20) What is the CNO cycle?
    The CNO cycle is a series of nuclear reactions that result overall in the fusion of four hydrogen nuclei into one helium nucleus.
  20. 21) What happens when a star exhausts its core hydrogen supply?
    Its core contracts, but its outer layers expand and the star becomes bigger and brighter.
  21. 22) When does a star become a main-sequence star?
    • when the rate of hydrogen fusion within the star's core is high enough to sustain
    • gravitational equilibrium
  22. 23) What is the basic definition of a black hole?
    any object from which the escape velocity equals the speed of light
  23. 24) Our Sun is considered a
    low-mass star.
  24. 25) In the context of understanding stellar lives, by "high-mass" stars we mean:
    stars with mass more than about 8 times the mass of our Sun.
  25. 26) What happens when the gravity of a massive star is able to overcome neutron
    • degeneracy pressure?
    • The core contracts and becomes a black hole.
  26. 28) Will our Sun ever undergo a white dwarf supernova explosion? Why or why not?
    No, because it is not orbited by another star.
  27. 32) What is happening inside a star while it expands into a subgiant?
    It is fusing hydrogen into helium in a shell outside the core.
  28. 33) What is the upper limit to the mass of a white dwarf?
    1.4 solar masses
  29. 34) What is the basic definition of a black hole? (2)
    A black hole is an object with gravity so strong that not even light can escape.
  30. 35) Which event marks the beginning of a supernova?
    the sudden collapse of an iron core into a compact ball of neutrons
  31. 36) What is the CNO cycle? (2)
    a type of hydrogen fusion that uses carbon, nitrogen, and oxygen atoms as catalysts
  32. 37) What is a carbon star?
    • a red giant star whose atmosphere becomes carbon-rich through convection from the
    • core
  33. 38) The helium fusion process results in the production of
    carbon.
  34. 39) What is a planetary nebula?
    gas ejected from a low-mass star in the final stage of its life
  35. 40) How does the gravity of an object affect light?
    Light coming from a compact massive object, such as a neutron star, will be redshifted.
  36. 41) What can we learn about a star from a life track on an H-R diagram?
    what surface temperature and luminosity it will have at each stage of its life
  37. 42) According to present understanding, a nova is caused by
    the fusion of hydrogen on the surface of a white dwarf.
  38. 1) A star's luminosity is the
    total amount of light that the star radiates each second.
  39. 2) On a HertzsprungminusRussell diagram, where would we find white dwarfs?
    lower left
  40. 5) On a Hertzsprungminus Russell diagram, where would we find stars that are cool and luminous?
    upper right
  41. 6) What are the standard units for luminosity?
    watts
  42. 9) What are the standard units for apparent brightness?
    watts per square meter
  43. 11) Suppose that you measure the parallax angle for a particular star to be 0.5 arcsecond. The distance to this star is
    2 parsecs.
  44. 13) The spectral sequence sorts stars according to
    surface temperature.
  45. 15) On a HertzsprungminusRussell diagram, where would we find stars that are cool and dim?
    lower right
  46. 17) On a HertzsprungminusRussell diagram, where would we find stars that have the
    • largest radii?
    • upper right
  47. 18) On a HertzsprungminusRussell diagram, where on the main sequence would we find
    • stars that have the greatest mass?
    • upper left
  48. 21) Which of the following is true about low-mass stars compared to high-mass stars?
    Low-mass stars are cooler and less luminous than high-mass stars.
  49. 22) Which of the following statements about spectral types of stars is true?
    All of the above are true.
  50. 24) If the distance between us and a star is doubled, with everything else remaining the same, the luminosity
    remains the same, but the apparent brightness is decreased by a factor of four.
  51. 25) If the distance between us and a star is doubled, the apparent brightness is decreased
    by a factor of four.
  52. 26) The more distant a star...
    the smaller its parallax.
  53. 27) Which of the following correctly states the luminosityminusdistance formula?
    apparent brightness = luminosity/4pi multiply (distance)2
  54. 28) Approximately, what basic composition are all stars born with?
    three-quarters hydrogen, one-quarter helium, no more than 2 percent heavier elements
  55. 29) On a HertzsprungminusRussell diagram, where would we find red giant stars?
    upper right
  56. 32) On the main sequence, stars obtain their energy
    by converting hydrogen to helium.
  57. 33) Suppose you measure the parallax angle for a particular star to be 0.1 arcsecond. The distance to this star is
    10 parsecs.
  58. 1) A star's luminosity is the
    total amount of light that the star radiates each second.
  59. 2) On a HertzsprungminusRussell diagram, where would we find white dwarfs?
    lower left
  60. 5) On a Hertzsprungminus Russell diagram, where would we find stars that are cool and luminous?
    upper right
  61. 6) What are the standard units for luminosity?
    watts
  62. 9) What are the standard units for apparent brightness?
    watts per square meter
  63. 11) Suppose that you measure the parallax angle for a particular star to be 0.5 arcsecond. The distance to this star is
    2 parsecs.
  64. 13) The spectral sequence sorts stars according to
    surface temperature.
  65. 15) On a HertzsprungminusRussell diagram, where would we find stars that are cool and dim?
    lower right
  66. 17) On a HertzsprungminusRussell diagram, where would we find stars that have the
    • largest radii?
    • upper right
  67. 18) On a HertzsprungminusRussell diagram, where on the main sequence would we find
    • stars that have the greatest mass?
    • upper left
  68. 21) Which of the following is true about low-mass stars compared to high-mass stars?
    Low-mass stars are cooler and less luminous than high-mass stars.
  69. 22) Which of the following statements about spectral types of stars is true? All of the above are true.
  70. 24) If the distance between us and a star is doubled, with everything else remaining the same, the luminosity
    remains the same, but the apparent brightness is decreased by a factor of four.
  71. 25) If the distance between us and a star is doubled, the apparent brightness is decreased
    by a factor of four.
  72. 27) Which of the following correctly states the luminosityminusdistance formula?
    apparent brightness = luminosity/4pi multiply (distance)2
  73. 28) Approximately, what basic composition are all stars born with?
    three-quarters hydrogen, one-quarter helium, no more than 2 percent heavier elements
  74. 29) On a HertzsprungminusRussell diagram, where would we find red giant stars?
    upper right
  75. 32) On the main sequence, stars obtain their energy
    by converting hydrogen to helium.
  76. 33) Suppose you measure the parallax angle for a particular star to be 0.1 arcsecond. The distance to this star is
    10 parsecs.

What would you like to do?

Home > Flashcards > Print Preview