3 ms·
An iron core is actually the precursor for either a black hole or a neutron star. There is an exothermic fusion chain of elements that are burned in stars, the
by chasil 2y ago
An iron core is actually the precursor for either a black hole or a neutron star.
There is an exothermic fusion chain of elements that are burned in stars, the last stage of which is silicon, that ends with iron.
https://en.m.wikipedia.org/wiki/Silicon-burning_process https://en.m.wikipedia.org/wiki/Silicon-burning_process
At iron, no further exothermic fusion is possible, so the core is no longer able to resist the pressure of collapse.
The iron atomic nuclei themselves break down, the protons combine with electrons to form neutrons where they are able, and if the total mass is below the Tolman–Oppenheimer–Volkoff, then neutron degeneracy pressure is able to stop the collapse, otherwise a black hole forms.
https://en.m.wikipedia.org/wiki/Tolman%E2%80%93Oppenheimer%E2%80%93Volkoff_limit https://en.m.wikipedia.org/wiki/Tolman%E2%80%93Oppenheimer%E...
A star needs to be 8 solar masses for this to happen. Our sun ends at carbon.
- myrmidon 2y ago> A star needs to be 8 solar masses for this to happen. Our sun ends at carbon. Wikipedia says the TOV limit is ~3 solar masses?
- cydodon 2y agoI know, that this doesn't help really, but in plasma physics as well as when dealing with degenerate matter and such 8 and 3 are the same number. Most of the time a scientist in these fields is happy to get the order of magnitude right! ;P
- lloeki 2y ago"Assume Pi is 1" is such a great conversation starter! https://www.xkcd.com/2205/ https://www.xkcd.com/2205/
- gus_massa 2y agoBut it the star is't a gas core made of Iron mixed with Hydrogen, Helium and other intermediate stuff, or it's a solid metallic almost pure Iron like on Earth? (IANAG neither)
- chasil 2y agoFor a sufficiently massive star, all of the hydrogen, helium, carbon, neon, oxygen, and silicon in the core are gone after silicon burning is complete. They were consumed as fuel to maintain the outward pressure of the core.