Astronomy Assignment #10: The Milky Way Galaxy

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Complete the assigned problems from the text listed below and address the Instructor Assigned Topic. Mathematical problems may be hand written. Write out the problem, show your work in solving the problem and state your answer in a complete sentence. Failure to complete all three of these tasks will result in less than full credit awarded. The Instructor assigned topic must be typed.

Review Questions From Chapter 14: The Interstellar Medium and the Milky Way from Nick Strobel’s Astronomy Notes

  1. What is the interstellar medium composed of?
  2. How does dust make stars appear redder than they actually are?
  3. How does dust cause the extinction of starlight?
  4. Where is the dust thought to come from?
  5. What are the characteristics of the gaseous part of the ISM? Is the gas all at the same temperature and density? How do you know?
  6. What are H II regions and how are they produced? What is going on at the atomic level?
  7. How is the 21-cm line radiation produced?
  8. Why is the 21-cm line radiation so important for determining galactic structure and mass?
  9. How is the 21-cm line radiation used to determine galactic structure and mass?
  10. What is the name for our galaxy and what kind of galaxy is it?
  11. How big is our galaxy? How many stars are in it and how do we know?
  12. How are Cepheids and RR-Lyrae stars considered to be standard candles? How can you find their luminosity?
  13. How can you use the period-luminosity relation to find distances?
  14. Why do variable stars like Cepheids, RR-Lyrae stars, and Mira variables vary in brightness?
  15. Where are we in the galaxy and how do you know? How can the distribution of globular clusters tell you about our place in the Galaxy?
  16. What are the four basic components of our galaxy? Where would old stars be found? Where would stars with very small amounts of ``metals'' (elements heavier than helium) be found? Where are new stars being formed? Where would stars enriched with ``metals'' be found?
  17. If you could analyze the spectra of 10 stars every second, how many years would it take you to check every star inside the Sun's orbit that is in our half of the Galaxy? [Hint: used the ``enclosed mass'' graph, divide by 2, and our Sun's distance from the center = 27,000 light years (8,400 parsecs).]
  18. How does the density wave theory explain why stars form in spiral arms?
  19. How do astronomers know the dark matter halo (corona) exists if it does not radiate anything our telescopes can detect?
  20. How do astronomers know that there is a very massive black hole at the center of the Galaxy?

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