Bert posted:

The last days of our sun will be when all its fusion fuel is just about
used up and finds the iron nucleus is to tightly held together ,and
fusion can't take place. The star"s core has been transmuted into iron.

Bert, the sun isn't massive enough to fuse elements heavier than Helium
because the sun doesn't have enough mass to get the core temperature up
to that level. Fusion in the core will stop when it has exhausted its
supply of core helium and shell Hydrogen, leaving the sun to contract
into a white dwarf star made mostly of carbon with a thin upper layer
containing lighter elements (some of the original small amounts of Iron
which is in the sun today may be still be around in the core). To get
much iron produced by fusion in the core of a star requires it to have a
*much* higher mass than the sun does.
--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

**********************************************
* Attend the 10th Annual NEBRASKA STAR PARTY *
* July 27-Aug. 1st, 2003, Merritt Reservoir *
* http://www.NebraskaStarParty.org *
**********************************************