What is the typical main sequence lifetime of a G-type star? ...

[stephzh]

What is the typical main sequence lifetime of a G-type star?
 
  A) 10 million years
  B) 100 million years
  C) 1 billion years
  D) 10 billion years
  E) 100 billion years

Question 2

Explain the significance of the Lyman Alpha Forest in studying the universe on the grandest of scales.
 
  What will be an ideal response?

[ApricotDream]

Answer to Question 1

D

Answer to Question 2

While the Lyman alpha line would normally be in the ultraviolet portion of the spectrum, for highly redshifted quasars, it is shifted into the visible, and then many more absorption lines, with lesser redshifts due to the gas clouds being closer to us, are observed against the background of the brilliant, distant quasar. We find that some heavy elements, like iron, show up quite early, suggesting that before the quasars existed, there was a first generation of massive stars making heavy elements.

[stephzh]

Thanks for the timely response, appreciate it

[dantucker]

Excellent