The hottest star in the Orion Nebula ____________hydrogen gas and makes it _____________.

The hottest star in the Orion Nebula ____________hydrogen gas and makes it _____________.
 
  a. ionizes; glow
  b. neutralizse; glow
  c. ionizes; swallow the star

Question 2

Regions of compression that move at their own speed in the disk and are outlined by the spiral arms are _____________.
 
  Fill in the blank(s) with correct word

Question 3

The youngest stars in the Orion Nebula and other star-forming regions also show
 
  a. circumstellar disks.
  b. jets.
  c. circumstellar disks and jets.

Question 4

As viewed from above or face-on, a ____________ spiral galaxy has many branches and spurs, making the arms less discernible.
 
  Fill in the blank(s) with correct word

Question 5

What causes the outward pressure that balances the inward pull of gravity in a star?
 
  a. the outward flow of energy
  b. the opacity of the gas
  c. the temperature of the gas
  d. the density of the gas
  e. the temperature and the density of the gas

Question 6

The center of the Milky Way galaxy must be less than 1 AU in diameter and contain at least 4 million solar masses. Therefore, the center of the Milky Way galaxy must be a ____________________,
 
  Fill in the blank(s) with correct word