joeyo1423 t1_j6mgpql wrote on January 31, 2023 at 11:09 AM

Reply to comment by BlueParrotfish in Eli5 Why can’t Stars use Iron in nuclear fusion? by Drippidy

Does it happen anyway? I understand that it would take energy rather than give, but do the extreme conditions in the core of such a star cause the fusion to happen anyway and steal some of the stars energy?

Chromotron t1_j6mhn7u wrote on January 31, 2023 at 11:21 AM

I have no idea why people down-voted you, this is a perfectly legitimate and pretty good question; some here are just jerks...

Yes, but rarely. And mostly at the end when the star is at its hottest in the center. I don't have numbers on how often it actually happens, but it definitely does.

At the most extreme end in particular, when a star goes supernova (not all do) it collapses so hard to its center that this creates extreme pressure and releases absurd amounts of energy. This fuses iron and all the other stuff beyond all limits; the energy is almost irrelevant, we are talking about hundreds of Earth masses(!!!) as pure energy. This is one of the two processes that creates the elements beyond iron in the amounts we find them (the other option are collisions of neutron stars).

ZackyZack t1_j6mh22c wrote on January 31, 2023 at 11:13 AM

Supernovas do it all the time

joeyo1423 t1_j6mhcd0 wrote on January 31, 2023 at 11:17 AM

That I do understand, but I wasn't sure if heavier elements fuse while the star is still active or if there is absolutely no fusion beyond iron until it blows up

rdrast t1_j6ouptd wrote on January 31, 2023 at 9:14 PM

No, for our Sun-like stars, iron is their eventual death.