Video Transcript
Which element the main sequence
stars primarily use for nuclear fusion?
Okay, so, to answer this
question, let’s first recall that the main sequence is literally the main phase
of a star’s life. If this is our star, slightly
egg-shaped for some reason, then the main sequence is set to begin when in the
core of the star, the temperatures and pressures are high enough for nuclear
fusion to begin. But the fact is that this star
was formed due to the gravitational collapse of clouds made up of mainly
hydrogen gas.
Now, hydrogen is the most
abundant element in the universe. It is also the lightest
possible element in the universe because it literally just needs one proton in
its nucleus. And it may or may not have some
neutrons. But even if it was just one
proton that would classify as hydrogen. So, it seems highly likely,
then, that what’s fusing in the core of the star is hydrogen because the star is
mainly made of hydrogen.
But the other important thing
is that nuclear fusion is a process that releases energy. In other words, nuclear fusion
is the energy source of our star. And when nuclear fusion is
happening, as a general rule, the lighter the element being fused, the more
energy is released by this process. And since hydrogen is the
lightest possible element in our universe, as well as what these stars are made
up of, that points us very strongly in the direction of hydrogen being the
element that main sequence stars primarily use for nuclear fusion.
