Where did Earth’s Uranium come from? It’s created in Supernovas and presumably Neutron star collisions. If it came from a Supernova, shouldn’t we be able to see the nebula from the explosion?
When the Uranium as created, what was the ratio of U235:U238? Does anyone know? That would give a pretty good idea of when it was created, right?
Uranium on earth came from ancient supernovae older than the solar system, that contributed to the interstellar dust and debris that collapsed to form the solar system.
Everything above Helium I believe was created in stars and most of the periodic table requires supernovae.
This answers my question pretty well:
Trace amounts of lithium were created in the big bang, a contaminant, really.
https://msutoday.msu.edu/news/2014/in-the-beginning-there-were-three-elements
Yes, not only was the supernova (or neutron star collision) more than 4.5 billion years ago (so very thinly dispersed by now) but that’s close to 20 rotations of the galaxy ago, so any remnant could be practically anywhere.
We can calculate the abundances of U-235 and U-238 at the time the Earth was formed. Knowing further that the production ratio of U-235 to U-238 in a supernova is about 1.65, we can calculate that if all of the uranium now in the solar system were made in a single supernova, this event must have occurred some 6.5 billion years ago.
This ‘single stage’ is, however, an oversimplification. In fact, multiple supernovae from over 6 billion to about 200 million years ago were involved. Additionally, studies of the isotopic abundances of elements, such as silicon and carbon in meteorites, have shown that more than ten separate stellar sources were involved in the genesis of solar system material. Thus the relative abundance of U-235 and U-238 at the time of formation of the solar system:
Cannot be inverted to a 'single stage' model age. Is essentially an accidental and unique value. Reflects the input of the explosive debris of many progenitor stars.
Or said another way, is practically everywhere; just at very very low concentrations.
Yes. Look all around you: Everything you see was part of that nebula. At least partly.
That article was adapted from a paper written in 1996 and partially updated in 2021. I don’t think even the updates do justice to the most recent findings. I believe the latest thinking is that almost all naturally occurring uranium (and every other naturally occurring element heavier than lead) is created from merging neutron stars, not supernova explosions.
Look in the mirror.
Your atoms are also largely from that primordial nebula.
