Post by: Werewolf on July 24, 2007, 07:07:45 AM
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?
Post by: K Frame on July 24, 2007, 07:13:02 AM
The energy of a supernova is so massive that it is capable of creating elements heavier than iron.
Post by: Brad Johnson on July 24, 2007, 07:17:16 AM
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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
Post by: charby on July 24, 2007, 07:42:07 AM
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.
Post by: Mabs2 on July 24, 2007, 07:55:54 AM
Who knows how long he had been working on everything else.
Post by: K Frame on July 24, 2007, 08:10:29 AM
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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?"
Post by: Brad Johnson on July 24, 2007, 08:15:14 AM
Brad
Post by: K Frame on July 24, 2007, 08:21:26 AM
Most simply reference the combining of lighter elements into heavier ones.
Post by: zahc on July 24, 2007, 09:11:12 AM
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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.
Post by: Gewehr98 on July 24, 2007, 09:15:07 AM
Post by: Brad Johnson on July 24, 2007, 09:22:37 AM
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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.
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
Post by: K Frame on July 24, 2007, 09:29:18 AM
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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.
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.