During the T-Tauri phase of a protostar, it A) begins a period ...

[skymedlock]

During the T-Tauri phase of a protostar, it
 
  A) begins a period of reduced activity.
  B) expands dramatically.
  C) may develop very strong winds.
  D) lies on the main sequence.
  E) changes its spin direction.

Question 2

Why were Type I supernovae so critical in discovering dark energy?
 
  What will be an ideal response?

[ynlevi]

Answer to Question 1

C

Answer to Question 2

These brilliant explosions are consistent standard candles, visible out to billions of light-years. Instead of finding the most distant galaxies slowing down as expected in a closed universe, the supernovae were even more distant than expected, as dark energy kept the universe forever expanding.

[skymedlock]

Excellent

[zacnyjessica]

Gracias!