Which of the following spectral types of stars could possibly be ten billion years old?
K
B
O
M
What does "zero age main sequence" mean?
The star will never enter the main sequence
The spectral type at which a star enters the main sequence
A star is fusing helium into carbon, oxygen and nitrogen
A star is swelling to a giant
Stars cannot fuse any element heavier than _____.
Nitrogen
Gold
Magnesium
Iron