Download 15-1/15-2 Reading Questions

Chapter 15 Reading Questions
Astronomy
Name:
Use pages 307 to 330 to answer the following questions:
Date:
15-1: The Nature of the Milky Way Galaxy
1. Astronomers commonly give the diameter of the galaxy as ________________ light years
with the sun located about ___________ of the way from the center to the edge.
2. Describe the disk of the Milky Way, including what types of stars live there and overall
properties
3. Describe the nuclear bulge of the Milky Way, including the types of stars that live there and
overall properties.
4. How did Sir William Herschel and his sister Caroline contribute to our understanding of the
Milky Way?
5. How did Harlow Shapley’s observations of star clusters contribute to our understanding of the
Milky Way (this isn’t a one-sentence answer! Check out how much space I’m leaving you!)
6. What are the two components of our galaxy and what are they made of?
7. We don’t live long enough to see our galaxy rotate significantly, but astronomers can observe
the radial _________________, proper __________________, and ___________________ of
stars then calculate their ______________. The results can tell us about the _____________ of
the galaxy and give us hints about its origin.
8. Draw a quick sketch of the difference between how disk stars and halo stars move.
15-2: The Origin of the Milky Way
9. Compare and contrast Population I stars and Population II stars, including what they’re made
of, where they are located, age, how they move, etc..
10. Describe galactic fountains (side note: I LOVE these!...you know, for what that’s worth)
11. The oldest open clusters are _____________ billion years old, while studies of the oldest
globular clusters suggest that the halo of our galaxy is at least _________ billion years old.
12. Detail the five steps in the formation of the milky way galaxy from the images on 319.
15-3: Spiral Arms
13. List three things present in the spiral arms of the milky way.
14. What are “spiral tracers”, what types of stars make good spiral tracers and why?
15. All spiral tracers are ____________objects. Because they don’t live long enough to
________________________ from the spiral arms, they must have ________________ there.
16. We live in a ________________ galaxy, but the spiral pattern appears slightly
______________________ with branches and __________________ and ________________.
17. List the two types of spiral patterns that our galaxy is though to be.
18. The materials needed to make stars is abundant in the ________________________.
19. Explain thoroughly the density wave theory of our galaxy.
20. The sun probably formed as part of a __________________ in a ______________ arm
roughly _____ billion years ago, left that cluster, and has circled the galaxy about _________
times.
21. Even if there were no star formation at all, rotating disk galaxies could form _____________
____________. But without star formation to make young, hot, luminous stars, the spiral arms
would be ___________________________. It is the star formation that _________________
the spiral arms and makes them so ______________________.
22. Explain self-sustaining star formation.
23. How is a spur on a spiral arm formed?
15-4: The Nucleus
24. If a ________________ photons of light left the center of the galaxy on a journey to Earth,
only ___________ would make it through the gas and dust of the nucleus.
25. List the possibilities of what might be at the center of our galaxy and why that is supported.