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From: andrew@alberta.UUCP (Andrew Folkins)
Newsgroups: net.astro.expert
Subject: Re: Forming The Elements
Message-ID: <571@alberta.UUCP>
Date: Thu, 27-Jun-85 19:36:39 EDT
Article-I.D.: alberta.571
Posted: Thu Jun 27 19:36:39 1985
Date-Received: Wed, 3-Jul-85 09:02:13 EDT
References: <243@ihnet.UUCP>
Reply-To: andrew@pembina.UUCP (Andrew Folkins)
Distribution: net
Organization: U. of Alberta, Edmonton, AB
Lines: 34
Summary: 

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.