Ast 111 FINAL

  1. Bulge
    The central portion of a spiral galaxy that is roughly spherical (or football shaped) and bulges above and below the plane of the galactic disk
  2. Disk
    The portion of a spiral galaxy that looks like a disk and contains an interstellar medium with cool gas and dust; stars of many ages are found in the disk
  3. Halo
    Spherical region surrounding that disk of a spiral galaxy
  4. interstellar medium
    • clouds of interstellar gas and dust
    • fill the galactic disk, obscuring view when we try to peer directly through it
  5. Orbits of disk stars
    • huge bob up and down through disk as they orbit
    • up and down motions of the disk stars give the disk its thickness
  6. orbits of halo and bulges stars
    much less organized than the orbits of stars in the disk
  7. star-gas-star cycle
    • galaxy recycling process
    • stars are born millions or billions of years with energy produces by nuclear fusion  dying only when they've exhausted their fuel for fusion. Starts return their material back to the interstellar medium through supernovae and stellar winds
  8. cosmic rays
    can cause genetic mutations in living organisms
  9. What do halos stars tell us about our galaxy history
    • disk population-contains both young stars and old stars, all of which have heavy element portions of about 2% like our sun
    • spheroidal population-consist of stars in the halo and he bulge both of which are roughly spherical in shape. Stars are older and have low mass
  10. How did Harlow Shapley realize we were not the center of our galaxy
    found that globular clusters to be centered on a point ten of thousands of light years from the sun
  11. What constellation is our galaxy  in
  12. How did Harlow Shapley estimate distance to globular star clusters?
    Using pulsating variable stars
  13. What is the location of the sun in the milky way
    in the galactic disk, roughly halfway between the center and the outer edge of the disk
  14. Why can we see all the way across the galaxy using radio waves but not visible light?
    • Milky waves clouds of gas and dust prevent us from seeing visible light
    • In the center we can find bright radio emission traces.  the source of the radio emission name Sagittarius A*
  15. Rotation curve
    a graph that plots rotational velocity against distance from the center of any object or set of ojects
  16. Spiral Galaxies
    • our milky way
    • look like flat white disks with yellowish bulges at their centers. The disks are filled with cool gas and dust. interspersed with hotter ionized gas, and usually display beautiful spiral arms
  17. Elliptical galaxy
    redder, rounder, and often longer in one direction that in the other. like a football. Compare with spiral galaxies, elliptical contains very little cool gas and dust though they often contain very hot  ionized gas
  18. Irregular galaxies
    • appear neither dislike nor rounded
    • contain young massive stars
  19. The two types of spiral galaxies
    • disk component- flat disk in which stars follower orderly circular orbits
    • spheroidal component-names for its roundeshape. stars  have many different orbits
  20. which galaxy is the most numerous galaxy in the universe?
    Elliptical galaxies
  21. Giant elliptical galaxies
    • Bigger than most dwarf  elliptical galaxies
    • only contain old stars 
    • very little cloud gas
Card Set
Ast 111 FINAL