Answer to Question 1
Hydrogen.
Answer to Question 2
Once the usable hydrogen fuel is all burned up, there remains a helium-rich core. Once fusion is finished in the star's core, there is insufficient pressure to prevent collapse due to gravity, and the contraction generates a huge increase in internal temperature, triggering a higher level of hydrogen fusion in the star's shell. The outer shell expands from the heat of accelerated fusion, but this expansion simultaneously cools the star's surface, yielding a large, cool star.
The Spectra of Stars with Different Surface Temperatures.
A flex-fuel vehicle often has a yellow gas cap, which is labeled “E85/gasoline”.
If the vacuum hose is removed from the fuel-pressure regulator when the engine is running, the ...
BLAST results showing a 280-base sequence of a chromosome 12 contig from rats
An insertion sequence (IS), shown in purple
Cis-element regulatory structures in eukaryotes