A Question for the Physics Gurus

[Werewolf]

Where do elements heavier than IRON come from?

I ask because it's my understanding (possibly a wrong understanding) that all the elements come from the stars.

Stars work on fusion. Start out with Hydrogen and when that's gone start fusing Helium, then Lithium right on up the periodic table until they hit Iron at which point the fusion process can go no further, the star novaes or super-novaes and spews out the ash of it's dead self into the surrounding galaxy.

So if fusion stops at iron where do the elements heavier than iron come from?

[K Frame]

Supernovas.

The energy of a supernova is so massive that it is capable of creating elements heavier than iron.

[Brad Johnson]

So if fusion stops at iron

It doesn't.  It stops at helium.  It is, however, a catalyst for other reactions.

A quick synopsis.
http://www.uwgb.edu/dutchs/PLANETS/Geochem.htm

Brad

[charby]

So if fusion stops at iron where do the elements heavier than iron come from?

Stop the questioning, it came from God and all was created in less than seven days.

[Mabs2]

He created the Earth in seven days.
Who knows how long he had been working on everything else.

[K Frame]

So if fusion stops at iron

It doesn't.  It stops at helium.  It is, however, a catalyst for other reactions.

A quick synopsis.
http://www.uwgb.edu/dutchs/PLANETS/Geochem.htm

Brad

Brad, this statement seems to counter that:

"In extremely massive stars there are shells of nuclear fusion where progressively heavier nuclei form. The end result of fusion is iron, the most stable nucleus. Iron nuclei cannot yield energy either by fusion or fission. So where do even heavier nuclei come from?"

[Brad Johnson]

Not really.  Fusion, in strict terms, stops at the creation of helium.  However, the energy in the cores of stars takes the helium and keeps doing stranger and strager things with it.  Interesting stuff, this.

Brad

[K Frame]

OK, I'm not seeing anything in any of the physics sites I'm scouting that says that nuclear fusion is limited only to combination of hydrogen to form helium.

Most simply reference the combining of lighter elements into heavier ones.

[zahc]

Where do elements heavier than IRON come from?

God.

Seriously, I think I have about a 20 page paper in my laptop case I got this summer at my internship that details theories on how the heavier elements were formed. Very laborious, but interesting. And quite speculational.

[Gewehr98]

Fusion of other nuclei to the iron mass, making heavier elements?  Ala' neutron capture...

[Brad Johnson]

OK, I'm not seeing anything in any of the physics sites I'm scouting that says that nuclear fusion is limited only to combination of hydrogen to form helium.

Most simply reference the combining of lighter elements into heavier ones.

Oh, my bad.  I should have been more specific.  I talking about the sun where Fusion refers to hydrogen/helium.  In general terms I guess it could refer to any reaction where the nuclei of two or more substances are combined.  Given the proper conditions and enough energy, I suppose you could fuse just about anything.

Brad

[K Frame]

OK, I'm not seeing anything in any of the physics sites I'm scouting that says that nuclear fusion is limited only to combination of hydrogen to form helium.

Most simply reference the combining of lighter elements into heavier ones.

Oh, my bad.  I should have been more specific.  I talking about the sun where Fusion refers to hydrogen/helium.  In general terms I guess it could refer to any reaction where the nuclei of two or more substances are combined.  Given the proper conditions and enough energy, I suppose you could fuse just about anything.

Brad

And that's the entire point of stellar fusion, right?

I'm pretty sure that the sun is a common type of star. The sun might not be the proper class of star for heavy element fusion, but Werewolf was talking about stars in general, not the sun specifically.

So, I'd have to stick with my original answer, that fusion can, and is responsible at least in part, for creating elements up to iron.