If you want to get even heavier elements like gold, uranium, and plutonium, you need a really violent event to happen — like two neutron stars merging. Or so we thought. Now, though, a new study published in Science examines the possibility that it merely takes a supernova to produce such elements. Maybe.

The story starts with the discovery of an extraterrestrial isotope here on Earth in the ocean crust: plutonium-244. This isotope was found alongside another radioactive one: iron-60. Both of these isotopes are evidence of something violent happening close-ish to our solar system millions of years ago, and then the interstellar gas and dust that contained all these radioactive elements lingered and found their way to Earth. We know they weren’t a part of the material that formed our solar system because these elements would have completely decayed in the past four billion years.

So why do these scientists think that a simple supernova, if a supernova could ever be thought of as simple, created the plutonium-244? Because it was found alongside that iron isotope. We know that iron-60 is formed in supernovae, and for the plutonium to be co-existing in the crust, they may have formed together. In a supernova. That happened near Earth. Yikes.

Lead author Anton Wallner notes, however: Our data could be the first evidence that supernovae do indeed produce plutonium-244. Or perhaps it was already in the interstellar medium before the supernova went off, and it was pushed across the solar system together with the supernova ejecta.

It’s an interesting line of research, and I’m curious to see where it goes. Either way, it continues to come back to the fact that, as Carl Sagan said: We are all made of star stuff.

More Information

ANU press release

“60Fe and 244Pu deposited on Earth constrain the r-process yields of recent nearby supernovae,” A. Wallner et al., 2021 May 14, Science