The solar system, along with other star systems, is on its way around the core of the galaxy, and the universe that passes through it cannot be considered completely empty. On the contrary, from the point of view of scientists at the Australian National University who study isotopes at the ocean floor, we often find ourselves in the midst of material that the Earth captures and enriches.
Remnant of a supernova explosion captured by the Chandra telescope
These are specific isotopes, and above all, iron-60, which has a half-life of only 2.6 million years, which simply means that all of the iron-60 that may have been on Earth at the time of its formation no longer exists after only stable nickel. The isotope must come from another source, and supernova explosions have left the material through which the solar system passed. Iron-60 has been found on the ocean floor in places isolated from the potential impact of human activity, and it is clear that it comes from outside Earth and our system.
The layers of sediment on the ocean floor are a time record in which Australian scientists found two important increases in iron-60 concentrations, indicating relatively close explosions in a supernova whose remnants can now be found several hundreds of light-years away. In places with a higher concentration of this isotope they decided to investigate further and also discovered a smaller but distinct size of the isotope plutonium-244. It is a relatively stable isotope with a half-life of 80 million years.
Regarding plutonium-244, the scientific community does not agree on its origin, that is, whether a supernova explosion was sufficient to form it, or whether it required a more monstrous event, such as a collision of an object with a neutron star. . However, the discovery of plutonium-244 at iron-60 concentration sites is the first strong evidence to support that it was caused by a supernova explosion. However, this may also be an act of chance, since plutonium-244 may have been an interstellar material before, so that only the remnants of a supernova explosion could be mixed up, i.e., as usual, more evidence must come before we can. We talk about a convincing theory.