🚀 go-pugleaf

In article <243@ihnet.UUCP> eklhad@ihnet.UUCP (K. A. Dahlke) writes:
>< H He C N O Si Fe >
>	A recent scientific American article (May i believe)
>described the explosion of a super nova.
  
>My question is, how did the other elements form;
>especially those above iron?

The elements up to iron are created by a process called nucleosynthesis, 
in which smaller atoms fuse together to produce larger ones.  The fusion
of elements up to iron produces energy, while the fusion of atoms heavier
than iron absorbs energy.  Thus, silicon fusion will produce enough  
energy to keep the star going (for a day or two, I think the figure was), 
while iridium fusion would suck up energy and cause the star to collapse 
under it's own weight (it's normally supported by radiation pressure from
the fusion processes in the core).
 
Elements heavier than iron require extra energy to produce, energy not 
normally present in the core of a star.  The energy is found, however,
in supernova explosions, where the temperatures and pressures of the
collapsing core are sufficient to produce the remaining natural elements.
When the core rebounds, producing the actual explosion, some of these
'impurities' are blasted out into space, where, after billions and
billions of years, they condense to form ingots in bank vaults :-).

I think I'll go re-read that article, it _was_ quite interesting.
 

-- 
Andrew Folkins
ihnp4!alberta!andrew
 
Underlying Principle of Socio-Genetics : 
       Superiority is recessive.

About forming the elements heavier than Fe:

It turns out that in its dying days (years, whatever), a star
will actually form the heavier elements by fusion.  The problem
is, this is an endothermic sort of thing; it requires more energy
than it produces.  As time goes on, the situation in the star is
going to head for its lowest energy state.  A supernova, on the
other hand, is a situation where a large amount of energy is
liberated in a short time, and the heavier elements will be
formed more than they would be inside the star.  Also, when the
supernova does its thing, it blows a lot of the material
(including the heavier elements it has formed) out into space, so
they won't be around it the star any more to be decayed by
fission.  A real astronomer could probably explain this better
than I did, but this is the gist of the situation as I understand
it.  Hope it helps.

-- 
Randwulf  (Randy Haskins);  Path= genrad!mit-eddie!rh

The energy released in a supernovae explosion provides the energy
necessary to drive the endothermic (energy absorbing) fusion reactions
that produce elements heavier than iron.  These elements are formed
and then thrown out into interstellar space.  Later stellar evolution
incorporates these elements into new stars and planets.

         Paul Pomes

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