My question is this: was there an amount of helium formed after the Big Bang, along with hydrogen? Or is all helium the product of nucleosynthesis at the cores of stars?

 

Can you please point me at sources about this?

Helium -3 and Helium-4 was produced moments after the big bang.

 

One of the tests of the big bang is the ration of Hydrogen and Helium.

 

Have a look at the Wiki article on Big Bang nucleosynthesis.

 

I recommend Liddle's book "An introduction to modern cosmology" for an accessible introduction to cosmology.

Thanks.

 

Book looks interesting, I already have Cosmology by Weinberg to study, but will check out Liddle's book as well.