Astr 2100 Descriptive Astronomy
Samples Questions for Test 3


  1. What is a binary star system? Are binary stars rare or common?
  2. What process is responsible for generating energy in the centre of stars?
  3. Which two properties of stars are measured by the Hertzsprung Russell diagram?
  4. What property of stars can be deduced by measuring their colour?
  5. How many hydrogen nuclei (protons) are destroyed in making one helium nucleus?
  6. What are sunspots?
  7. What is the name of the region of the Sun which we can see?
  8. Large sheets of gas are sometimes seen escaping from the surface of the Sun and penetrating into (and even beyond) the atmosphere. These are known as _______________
  9. What colour are the most massive main sequence stars?
  10. How do we measure the distance to nearest stars?
  11. Our own Sun is currently ____________
  12. Which two processes are responsible for transporting energy from the inside of our Sun to the outside?
  13. If star A has a relative magnitude of 3.2 and star B has a relative magnitude of 2.6, which one is the brighter?
  14. What two other quantities do you need to know in order to determine the luminosity of a star?
  15. How is the radial speed of a star measured?
  16. Where does the energy of the Sun come from?
  17. Because of nuclear fusion, what happens to the mass of the Sun?
  18. If a star is 50 parsecs away, what is its parallax angle?
  19. If the parallax angle for a star is 0.017 arc seconds, how far away is it (in parsecs)?
  20. How many light years are there in one parsec?
  21. If the absolute magnitude and relative magnitude of a star are equal, how far away is it?
  22. If a star is 100 pc away, how far is this in light years?
  23. How is it that a cool red star such as Aldebaran (the eye of the bull, in the constellation Taurus) is so bright?
  24. What is the source of energy for a main sequence star?
  25. What (approximately) is the surface temperature of the Sun?
  26. What (approximately) is the core temperature of the Sun?
  27. What (approximately) is the power output of the Sun, in watts?
  28. Approximately, what is the diameter of the Sun in miles?
  29. Why should you not look directly at the Sun?
  30. How far is the Sun from the Earth?
  31. Arcturus is 100 times as luminous as the Sun, but its surface temperature is only ½ that of the Sun. What is it radius?
  32. If a star is twice the size of the Sun, but has a surface temperature of only 3000 K, what will be its luminosity (relative to that of the Sun)?
  33. Stars A and B have the same relative magnitude. If star A has a luminosity equal to four times that of star B, and is 10 lyr away, how far away is star B?
  34. What is the distance (in light years) to a star whose parallax angle is 0.0033 arc seconds?
  35. A star has a surface temerature of 4500 K. If its relative magnitude is 7.7, how far away is it?
  36. A type I supernova has a relative magntiude of 12.0. How far away is it?
  37. Light from a star has a measured wavelength of 500.17 nm. If the same light is measured in the lab its wavelelngth is only 500 nm.
    1. Is it moving towards us or away from us?
    2. What is its speed relative to us?
  38. Light from a distant galaxy has a measured wavelength of 720 nm. If the same light is measured in the lab its wavelelngth is only 656 nm.What is its speed relative to us?
  39. A pair of binary stars orbit each other at a distance of 8 AU, taking 6 years to orbit around each other. If one star has three time the mass of the other, what are their individual masses?

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