The birthplaces of stars correspond to the ________ clouds in the ...

[meagbuch]

The birthplaces of stars correspond to the ________ clouds in the interstellar medium.
 
  Fill in the blank(s) with correct word

Question 2

Explain how gas in a protostellar disk spirals onto the central star.
 
  What will be an ideal response?

[meganmoser117]

Answer to Question 1

densest (and coldest)

Answer to Question 2

Gas in a protostellar disk will orbit like planets, with the innermost particles moving faster than outer ones. This causes friction and therefore heating of the gas which therefore produces light (thermal radiation). Energy must be conserved so the gas loses gravitational potential energy and moves closer to the star. Because the gas is still in orbit, its overall motion is that of a spiral.