3 ms·

Blue hypergiants only last about 10 million years. What really is necessary to know, I believe there is still debate, is whether main sequence supernovae can g

Blue hypergiants only last about 10 million years. What really is necessary to know, I believe there is still debate, is whether main sequence supernovae can generate all the necessary elements. I believe gold and heavier are might not be possible with normal supernovae and may require neutron star mergers to generate. I believe earth tectonics, not a small aspect of Earth's long term stability/cycle, need radioactives to maintain a liquid core (not to mention the magnetic shield provided by the core). Still, an earth like world in a mostly stable/quiet area of a galaxy may be possible only a few billion years after the big bang with some luck with blue hypergiants and a lucky neutron star merger, if that is in fact necessary for heavy elements and radioactives.

BlueTemplar 6y ago
How do you get any elements out of a neutron star ?
- AtlasBarfed 6y ago
  The collisions have so much energy that matter (neutronium) is ejected. I believe it might happen in neutron star - black hole mergers too due to the crazy gravitational energy involved. Anyway, you eject clumps of "pure neutronium" then they will undergo rapid evolution to elements as neutrons decay to protons in order as they try to become stable elements. I'm not a nuclear physicist... I'm not a physicist.... Personally, if neutron star mergers are responsible for most heavy elements, then the "island of stability" above the current transuranics probably doesn't exist, because neutronium would almost certainly traverse those islands as it followed all the different decay chains.
  - jacquesm 6y ago
    That stability is the physics interpretation of the word stability, where stability could be measured in hours, minutes or even seconds rather than on a timescale where those elements would be present in measurable quantities billions of years later.
  - BlueTemplar 6y ago
    Huh, I missed that development ! Yeah, I guess that there's some (literally !) "golden middle", where the energies involved are high enough to eject some large fraction of the neutronium, while the masses involved aren't high enough to immediately result in a black hole ?

BlueTemplar 6y ago

How do you get any elements out of a neutron star ?

AtlasBarfed 6y ago
The collisions have so much energy that matter (neutronium) is ejected. I believe it might happen in neutron star - black hole mergers too due to the crazy gravitational energy involved. Anyway, you eject clumps of "pure neutronium" then they will undergo rapid evolution to elements as neutrons decay to protons in order as they try to become stable elements. I'm not a nuclear physicist... I'm not a physicist.... Personally, if neutron star mergers are responsible for most heavy elements, then the "island of stability" above the current transuranics probably doesn't exist, because neutronium would almost certainly traverse those islands as it followed all the different decay chains.
- jacquesm 6y ago
  That stability is the physics interpretation of the word stability, where stability could be measured in hours, minutes or even seconds rather than on a timescale where those elements would be present in measurable quantities billions of years later.
- BlueTemplar 6y ago
  Huh, I missed that development ! Yeah, I guess that there's some (literally !) "golden middle", where the energies involved are high enough to eject some large fraction of the neutronium, while the masses involved aren't high enough to immediately result in a black hole ?