The Milky Way and Other Galaxies

• If we could view the Milky Way from above the disk, we would see its spiral arms.
• Dusty gas clouds obscure our view because they absorb visible light.
• The primary features are:

  Disk, bulge, stellar halo, globular clusters

  A) Stellar halo

  B) disk

  C) thin disk

  D) galactic

  E) sun

  F) budge

  
• What are the three major types of galaxies?

  1. Spiral
  2. Elliptical
  3. irregular
• Much of the star formation happens in the spiral arms of the disk.
• Blue - white color indicates ongoing star formation
• Red - Yellow color indicates older star population
• Shells of stars observed around some elliptical galaxies are probably the remains of past collisions.
• Spin: The initial angular momentum of the protogalactic cloud could determine the size of the resulting disk.
• Density: Elliptical galaxies could come from dense protogalactic clouds that were able to cool and form stars before gas settled into a disk.
• It is the interstellar medium that makes new star systems.