# Why does a star die once it has iron?

I found out that iron is the death element for stars, but I couldn't find why can anyone knowledgeable on stars explain why iron causes the star to die?

This is the binding energy of some elements as a function of their number of nucleons

Since fusion leads to a higher number of nucleons, what a star does is to progressively move from left to right on this plot.

So if you start on the left, say H, you merge two, and the result has a larger binding energy, so energy is released. But that behavior is broken when you reach Fe$$^{56}$$, at that point, you need extra energy. Since the star cannot produce it, it stops fusing material, and it dies off

• @Luna Glad it was of help – caverac Jan 25 at 20:06
• @Luna It can be frustrating, sorry you had a bad experience with your first post – caverac Jan 25 at 20:12
• my bet is they down-voted thinking this person is crazy – Little Bowsette Jan 25 at 20:13
• @Luna The site has a strong policy against homework-type questions which, in my humble opinion, ends up being a bit counterproductive. But ... it is what it is. Maybe that's the reason some users decided to downvote your post (just guessing), I just hope this doesn't discourage you from keep posting your questions as it really helps growing the community – caverac Jan 25 at 21:05
• @Luna I understand that, that's what I mean by counterproductive. Because some users prefer just to jump the guns and down-vote, or mark as off-topic, instead of taking the time to see the value in the question. – caverac Jan 25 at 21:11

A star "dies" when the fusion stops. 56Fe is the most stable nucleus that exists so it is the ultimate fusion product. Any nucleons contained in it no longer contribute to the energy production.