A mystery of our solar system’s space is getting closer to being solved thanks to supernovae discovered in deep-sea sediments.
Professor Anton Wallner, a nuclear physicist from the ANU, led the study suggesting that the Earth has been traveling for the past 33,000 years through a cloud of slightly radioactive dust.
Professor Wallner stated:
“These clouds could be remnants of previous supernova explosions, a powerful and super bright explosion of a star,”
He conducted the study at the ANU Heavy Ion Accelerator Facility (HIAF).
Also, he holds joint positions at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and Technical University Dresden (TUD) from Germany.
The scientists analyzed several deep-sea sediments from two locations that can be traced back to 33,000 years ago using the extreme sensitivity of HIAF’s mass spectrometer.
They discovered clear traces of the isotope iron-60, which forms when stars die in supernovae.
Iron-60 is a radioactive isotope that decays entirely in approximately 15 million years, which means that any iron-60 discovered on Earth probably has formed a lot later than the rest of the 4.6-billion-year-old Terra and arrived here from nearly located supernovae before settling on the bottom of the planet’s oceans.
Professor Wallner previously discovered traces of iron-60 at approximately 2.6 million ago, and maybe another sample from 6 million years ago, which means that the planet traveled through fallout clouds from nearby supernovae.
For the past few thousand years, our solar system has been traveling through a thicker cloud of gas and dust, called the Local Interstellar Cloud (LIC), which has unclear origins.
If the cloud had formed during the past few million years thanks to a supernova, it would be packed with iron-60, and that’s why the team searched more recent sediments.
“There are recent papers that suggest iron-60 trapped in dust particles might bounce around in the interstellar medium,” Professor Wallner said. “So the iron-60 could originate from even older supernovae explosions, and what we measure is some kind of echo. More data is required to resolve these details.”