What determines the abundance of elements?

martix

I was just watching a very particular old documentary, when the question hit me.
I could probably manage an educated guess, but I don't really know what exactly determines how much of a certain element there is(except H and He, those are obvious).

Borek

What is the source of other elements?

dschlink

The source of all elements other than hydrogen, helium and some lithium is fusion in aging suns and supernovas. Fusion gets you to iron, but anything heavier is created during supernova explosions. We don't have a handle yet on the exact reactions involved or what controls the abundance, but models are getting better every year.

martix

So... basically no answer to that question yet. :)
That's surprising.

I know that supposedly Carbon also gets produced at some point at the end phases of a stars life.

There's also the question why elements like boron or beryllium(4/5) are rarer than say cobalt(first element after iron, which is as far as I know that heaviest exothermally fusing element).

Borek

Actually the answer is here, you just have to think for a moment. My question was not a random one.

It is mainly a matter of the sample history. Metals (in astrophysics sense) are synthesized in stars, when (and if) the star explodes as supernova, they are scattered around, then they are included in the next generation stars, or separated due to the stratification in the gas clouds, and so on. Whatever you observe depends on what happened before.