What happens to the amounts of hydrogen and helium as fusion continues in star?
1 Answer
The amount of Hydrogen and then Helium in a star's core get consumed by fusion reactions.
Explanation:
Stars are mainly Hydrogen and smaller quantities of Helium. Fusion reactions only take place in a star's core or the layers immediately about it. In the case of the Sun the core is about 20% of the Sun's radius.
The Hydrogen and Helium in the outer layers of a star are not involved in fusion reactions, so the amounts don't change much. That is why the debris left from the death of a star have sufficient Hydrogen to form another.
In the core of a star, Hydrogen is fusing into Helium while it is main sequence. When the core Hydrogen is consumed then Helium fusion starts. This fuses Helium into Carbon and Oxygen. In the case of larger stars Carbon fuses into heavier elements until the core is mainly Iron.
So most of a star's Hydrogen and Helium persist in similar quantities. In the core however, Hydrogen and Helium are fused into heavier elements.
