Approximately, what basic composition are all stars born with?

1 Answer
Sep 27, 2017

As a first order approximation all stars are 90% hydrogen.

Explanation:

95% maybe a better value, apparently it varies surprisingly little ... mystery is all. Forgot to say, most of the rest is helium, with only sparse amounts of heavier elements (they must be present, otherwise we wouldn't be) produced through fusion reactions.

Elements beyond iron can only be formed in supernovas.