What gas makes up the majority of an old star?

Answer 1

Even in an old star just before it explodes, the majority of the star in hydrogen gas. But as the hydrogen is fused, the helium residue begins to interfere with the hydrogen fusion, like ashes in the bottom of a fireplace.

Answer 2

Stars are made mostly of hydrogen though there are many other elements that help to build one. And toward the end of its life cycle a star will actually be made of a large portion of helium as well which it will begin to fuse, along with hydrogen or instead of hydrogen, in its core.

Answer 3

Depends how you define old.

Stars that are off the "main sequence" have used up all the available hydrogen and are now fusing helium.

Answer 4

Hydrogen is the fuel for all new stars.

Answer 5

Hydrogen followed by Helium.

Answer 6

hydrogen

Answer 7

Helium