Researchers recently came across traces of highly radioactive iron while studying the fallen snow in Antarctica. According to the researchers, these traces are most likely remnants of a supernova.

Scientists have long believed that dust from space regularly rains down on Earth. These usually come from the debris produced by the violent formations of planets and new stars.

On Earth, Antarctica is considered as one of the few regions where cosmic dust can be easily found due to its remote and unspoiled status.

Recently, a team of researchers combing through the fresh snow in Antarctica came across traces of iron-60, which is a variant of iron that’s highly radioactive. According to previous studies on fossilized remains of bacteria as well as deep-sea sediment, iron-60 came to Earth following a supernova explosion. Studies on these traces revealed that they may have arrived at Earth around 1.7 to 3.2 million years ago.

Unlike in the previous studies, the recent discovery marks the first time that iron-60 has been detected in Antarctic snow. For the researchers, this strongly indicates that the supernova debris may have entered Earth within the last two decades.

“I was personally surprised, because it was only a hypothesis that there might be iron-60 and it was even more uncertain that the signal is strong enough to be detected,” Dominik Koll, a nuclear physicist from the Australian National University told Science Alert.

“It was a very joyful moment when I saw the first iron-60 count appear in the data, because that means that our overall astrophysical picture might not be too wrong,” he added.

The researchers hypothesized that the Solar System travels through a dense interstellar cloud filled with dust. The bulk of this interstellar dust is composed of the debris that came from a supernova.

Since the traces of iron-60 that they discovered came to Earth within the last 20 years, the researchers concluded that the Solar System is currently near or within the interstellar cloud.

According to the researchers, their findings could provide a brief background regarding the life and death of stars in the galaxy.

The findings of the researchers were presented in a new study published in Physical Review Letters.

Supernova remnant
Supernova remnants are the debris from exploded stars. G292.0+1.8 is a rare type of supernova remnant observed to contain large amounts of oxygen. Because they are one of the primary sources of the heavy elements (that is, everything other than hydrogen and helium) necessary to form planets and people, these oxygen-rich supernova remnants are important to study. The X-ray image of G292+1.8 from Chandra shows a rapidly expanding, intricately structured field left behind by the shattered star. The image is colored red, green, teal and purple in X-rays ranging from the lowest to highest energy levels.Recently the first detection was made of iron debris from the exploded star. Authors constructed a map of this debris, along with that of silicon and sulphur, to understand more about the explosion. They found that these three elements are mainly located in the upper right of the remnant. This is in the opposite direction from the neutron star that was formed in the explosion, and was then kicked towards the lower left of the remnant. This suggests that the origin of this kick is gravitational and fluid forces from an asymmetric explosion. If more than half of the star’s debris is ejected in one direction, then the neutron star is kicked in the other direction so that momentum is conserved. This finding argues against the idea that the copious amounts of neutrinos formed in the supernova explosion were emitted in a lop-sided direction, imparting a kick to the neutron star. NASA/CXC/SAO
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