When I went to school, we were taught that main sequence stars didn't fuse past iron, since doing so absorbs energy rather than produces it. Only the profligately counterfactual absurdity of a supernova can run the fusion equations backwards to fill out the top of the periodic table.
Like everything you learn in school, that's a useful lie. Chemical reactions are a bidirectional equilibrium process, and similarly not all the baryons involved in stellar-core reactions have read the astrophysics textbooks. "Peculiar Stars" like Przybylski's star---a 1.4 M☉ F5 main sequence beastie about a hundred parsecs out in Centaurus---spilled the nuclear tea with their abundance of rare earths, actinides and even transuranics in their atmospheres. What's just fucking outstandingly cool about this whole impossible pie with outrageous sprinkles is that these appear to be **fission products**, that is some /really/ heavy elements in the 125+ range are getting burped up from the core, and sticking around for quite a while writing us a spectral postcard full of all manner of unusual adjectives.
This has made the particle physics grrrls suuuper mad, because you just can't make these elements by thwacking protons or neutrons into smaller nuclei; "you can't get there from here" as the old joke goes. Because the "island of stability"on the periodic table where the big honkers exist is above a region in the teens that has no even slightly stable isotopes, you simply can't climb the ladder a rung at a time---even alpha particles won't get you there. You've got to, well....we don't know.
Following in the footsteps of Antoni Przybylski (or "Bill" as his Australian colleagues called him), we decided it was simpler to just Go And See how this works rather than waiting for the theoreticians.
A hundred parsecs is a bit of a road trip, even at Skip Factor Epsilon, so we had time to argue whether there was a neutron star in tight orbit around Bill's Bastard, or just a particularly saucy primordial dust cloud in its ancestry. Fermi (no relation to Enrico save by temperament) reckons that we'll find these elements to be artificial after all, dumped there by ET as a way to send a message.
Well, it sort of was and it wasn't. The transuranics are natural, and the folk who got there first (not us, by a long margin) are disinclined to share details about the formation process. But they sell their mined ultrametals for a fair price, and we're headed home full to the gunwhales with Billium and a bunch of other shiny plus-sized elements. Fermi is already designing a hoverboard that uses Ladygaganium-378 in its field-coils.
