Shared Flashcard Set

Details

Astronomy
Galaxies
50
Other
Undergraduate 1
05/06/2008

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Cards

Term

1. What part of the Milky Way Galaxy is composed of globular clusters?

Definition
The Halo
Term

2. What part of the Milky Way Galaxy is composed of spiral arms?

Definition
The Disk
Term

3. How far is the sun from the center of the galaxy in the disk?

Definition
30,000 ly
Term

4. How old is the Galaxy?

Definition

14 billion years

Term

5. What types of stars are found in the disk?

Definition
Population I stars- young and metal-rich
Term

6. What types of stars are found in the halo?

Definition
Population II stars- old, metal-poor
Term

6. What types of stars are found in the halo?

Definition
Population II stars- old, metal-poor
Term

7. What types are found in the bulge?

Definition
Intermediate age and metal-rich stars
Term

8. What is the name of the arm that the sun lies on?

Definition
Orion’s Arm
Term

9. What do the spiral arms contain?

Definition
Young stars and interstellar gas and dust
Term

10. What is a galactic rotation and how long is suns galactic year?

Definition
Stars orbit of center of galaxy; 200 million years
Term

11. What is in the core or center of entire galaxy?

Definition
Super massive black hole
Term

12. What are the most visible parts of the halo?

Definition
Globular star clusters- each with about 2 million pop. II stars
Term

13. How is the orbit of the clusters?

Definition

Elliptical- used to determine mass of galaxy!!

Term

14. What did the Curtis-Shapely Debate argue?

Definition
The state of universe
Term

15. What was believed after debate of the state?

Definition
Milky Way was everything
Term

16. How did Hubble settle the debate?

Definition
Found Cepheid variables in Andromeda galaxy
Term

17. What is the period of the star RR Lyrae (bright and dims)?

Definition
12 hours
Term

18. What is a Cepheid Variable?

Definition
Blinking type of behavior over a week
Term

19. What does type I contain?

Definition
Metals
Term

20. What does type II contain?

Definition
Hydrogen and helium
Term

21. Why do they appear to blink?

Definition
Shrinking and growing from hot to cold, w/o established hydrostatic equilibrium
Term

22. Where are these stars located on the HR Diagram?

Definition
Instability strip
Term

23. Up to how many galaxies have been found to be in a cluster?

Definition
1000
Term

24. How does a galaxy become elliptical?

Definition
Random motion is large
Term

25. What is the most common type of elliptical galaxy?

Definition
Dwarf Elliptical- 1000s ly across
Term

26. How do spiral galaxies form?

Definition
If random motions in pregalactic cloud are small
Term

27. What kind of galaxy has no arms?

Definition
Lenticular galaxies
Term

28.  What law states that the further a galaxy is from us the faster its observed recession speed is

Definition
Hubble’s Law
Term

29. How is recession speed measured?

Definition
By Red-shift- Doppler shift of absorption lines
Term

30. What tells us the rate at which the universe is expanding? (slope)

Definition
Hubble’s constant
Term

31. How many galaxies does our own cluster contain?

Definition
40-45 galaxies
Term

32. What is the nearest cluster named- which we are being drawn towards b/c of large mass?

Definition
Virgo
Term

33. What percent of Universe is dark matter?

Definition
90%
Term

34. What are large regions of of empty spaces b/w filaments containing few or no galaxies?

Definition
Voids
Term

35. What type of peculiar galaxy is spiral with really bright nucleus?

Definition
Seyfert Galaxies
Term

36. What are the most distant objects with very broad emission lines and very active nucleus with jets or material shooting out?

Definition
Quasars
Term

37. What is the age characteristic of Quasars? How do we know?

Definition
Very young and very bright, red shifts
Term

38. What is the central source of a quasar that emits strong radio emission?

Definition
Synchrotron
Term

39. What may produce the power of quasars by converting gravitational energy to radiation?

Definition
Super-massive black holes
Term

40.  How do we know a quasar is present since we can’t see the host?

Definition
Light passing is bent
Term

41. What gravitational lens was actually one object but appeared to have 5 identical dots ?

Definition
Einstein’s Cross
Term

42. What is the study of the universe’s nature and evolution?

Definition
Cosmology
Term

43. What type of geometry says that parallel lines stay parallel?

Definition
Flat or Euclidean geometry (real)
Term

44.  What is the density needed to close or halt expansion of the universe?

Definition
Critical Density- seems to never be reached
Term

45. How much radiation does the Big Bang theory predict to be left over throughout the universe?

Definition
3 Kelvin- started expansion through red shifts
Term

46. What event started the universe that cannot be explained by physics?

Definition
Primeval Fireball
Term

47. What forces bind atoms together?

Definition
Gravity and electromagnetism
Term

48. Who was able to combine both of the above together making them consistent?

Definition
Maxwell
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