Scientists looking to learn about supernovae typically look at the skies for answers, but this does not mean they cannot glean valuable information somewhere else. In a new research, for instance, astronomers looked at tiny particles lying at the bottom of the ocean to learn about ancient supernovae.
Supernovae are powerful explosions that occur as a result of massive stars reaching the end of their lives. When these powerful events happen, many elements, including those that are essential for supporting life such as iron, iodine and potassium are forged.
Our concept of supernovae, however, could be changed as scientists analyzed extraterrestrial dust that settled deep on the ocean floor believed to be from supernovae in order to know how much heavy elements were produced by these galactic explosions.
Study researcher Anton Wallner from the Research School of Physics and Engineering explained that there were some debris from these explosions that fell on our planet as the Earth travels.
For their new study published in the journal Nature Communications, Wallner and colleagues conducted an analysis of a sample of the Earth's crust that represented the past 25 million years as well as deep-sea sediments from the bottom of the Pacific Ocean. They found that heavy elements such as plutonium and uranium exist in lesser quantities compared to what have been expected.
When the researchers measured the quantities of plutonium-244, a radioisotope known to be of supernovae origins, they discovered that its amount was 100 times less than what they had predicted. The radioisotope has a half life of 81 million years and this makes it a good indicator of the number of supernovae explosions that occurred nearby in recent history.
The researchers said that plutonium-244 that may have existed when our planet formed more than 4 billion years ago had already decayed a long time ago.
"So any plutonium-244 that we find on earth must have been created in explosive events that have occurred more recently, in the last few hundred million years," Wallner said.
The researchers added that the heaviest elements did not appear to have formed in a manner that collaborates with current theories on supernovae and that more explosive and rarer galactic events may have created them, such as when two neutron stars merge.
Wallner said that since heavy elements like plutonium, uranium and thorium can still be found on Earth, it indicates the possibility that such an explosive event may have occurred close to our planet around the time of its formation.
