If the proton does not decay, will black dwarfs become iron stars in 10^1500 years>
First off, what's a black dwarf?
Second, most stars don't even fuse all the elements up to iron.
Third, for the stars that do fuse elements up to iron, the heavy elements are almost always blown off in the ensuing supernova explosion, leaving a neutron star. Again, I don't see any way this neutron star could become an "iron star".
From the http://en.wikipedia.org/wiki/Black_dwarf" [Broken]
So I don't understand what you mean by iron stars. Black dwarfs are just white dwarfs but dimmer (aka lower in temperature). They are made from and I quote the quote above (might be a first), "electron-degenerate matter".
There is no iron at this step. You've just barely touched the CNO cycle (carbon,nitrogen,oxygen) when a star like our sun becomes a white dwarf.
i think iron stars would be cool as hell, to be honest. and given enough time, i could maybe imagine them possibly forming, although what protonchain and his quote say makes me think that there might not be enough energy within a black dwarf to even fuse protons together, since the electron-degenerate matter has already "fused all the elements which it has sufficient temperature to fuse."
p.s. is proton decay hypothetically like 10^31 years?
<<In 10^1500 years, cold fusion occurring via quantum tunnelling should make the light nuclei in ordinary matter fuse into iron-56 nuclei (see isotopes of iron.) Fission and alpha-particle emission should make heavy nuclei also decay to iron, leaving stellar-mass objects as cold spheres of iron.>>
From Wikipedia. That is if proton decay doesn't occur. So presumably that would make black dwarfs become iron stars. Those iron stars would then become neutron stars in 10^10^76 years.
Forgive me if this is a stupid question, but if quantum tunneling can fuse light nuclei into heavier ones, why can it not cause heavier nuclei to break apart into lighter ones?
Quantum tunneling lets you push through a barrier if there is a lower energy on the other side, in simple terms it lets you borrow energy for a short time. Splitting larger nuclei is not energetically favourable, fusing lighter nuclei does give you energy if you can overcome the barrier.
Fusing nuclei is energetically favorable for elements below iron, which is why the process stops at iron. Got it!
Cold spheres of iron! How would these orbs appear? I understand they could not be seen by human eyes because deep into the Dark Era, there would be no light source to illuminate them. They would not rust because there would be no oxygen to oxidize them. Would they rotate? How big would they be? What color would they be? Imagine piloting an out-of-control time travel device, stranded in this silent, black universe, haunted by these unseen cold speheres of iron. What an image! Anyone have any thoughts on this?
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