Assignment 4

  1.    The visible surface of the sun is called what?
  2. Granulation is caused by what type of currents in the outer part of the sun?
  3. What is the outermost part of the sun’s atmosphere called?
  4. How did Galileo conclude that the sun was rotating?
  5. The sunspot cycle has a length of how many years?
  6. The length of time it takes the sun to rotate [increases, decreases] as you go north or south of its equator.
  7. The darkest part of a sunspot is called the [penumbra, umbra].
  8. What is meant by the Maunder minimum? [Be brief]
  9. The splitting of spectral lines into several parts because of a magnetic field is called what type of an effect?
  10.    What causes an aurora? [Also called the Northern and Southern lights.]
  11. What is the name of the model that explains the sunspot cycle as a consequence of the sun’s differential rotation?
  12. There are how many known forces in nature?
  13. Stars produce their energy by means of nuclear [fusion, fission].
  14. The sun produces its energy by converting hydrogen into what element?
  15. A positron is made in the [first, second, third] step of the proton-proton chain.
  16. Has the solar neutrino problem been solved?
  17. The larger its parallax the [closer, further away] is a star.
  18. The nearest star has a parallax of how many seconds of arc?
  19. Suppose a star has a parallax of 0.25 seconds of an arc. What is its distance in parsecs?
  20. What kind of measurements did the Hipparcos Satellite make?
  21. Suppose we move 8 times further from a star. How many times fainter will it appear?
  22. The absolute magnitude of a star is defined as its apparent visual magnitude as seen from a distance of how many parsecs?
  23. What is the absolute magnitude of the sun?
  24. Does the luminosity of a star depend upon how far away it is?
  25. Suppose stars A and B have the same temperature, but B is less luminous than A. Which one has the larger diameter?
  26.    As you go to the right in the H-R diagram the temperature [increases, decreases].
  27. The majority of stars are [white dwarfs, giants, main-sequence].
  28.    To which luminosity class does the sun belong?
  29. Polaris (the North Star) is an example of a [white dwarf, main sequence, supergiant] star. [Hint: see page 143].
  30. Why are the Balmer lines in the spectra of giant stars narrower than those for main-sequence stars?
  31. Binary stars are [common, very rare].
  32. Binary stars allow us to determine what very important property of stars?
  33. In a binary system the center of mass lies closer to the [more massive, less massive] star.
  34.  What type of star is Sirius B? [main sequence, white dwarf, giant]
  35. Why does a spectroscopic binary system only allow us to find a lower limit to the masses of the stars?
  36.   It takes about how many hours for the stars of Algol to revolve?
  37. [Giants, White dwarfs, Main sequence stars] best obey the mass-luminosity relation.
  38. Which has the higher average density, supergiants or main-sequence stars?
  39. The sun converts how many million tons of mass intro energy each second?
  40. Three types of binary systems are called visual, spectroscopic, and what?