What was the early universe made of? We came closer to an answer this weekend

What was the early universe made of? We came closer to an answer this weekend

A 35-year old scientific debate was finally put to bed over the weekend when scientists discovered that an incredibly rare and volatile element, curium, was indeed present at the formation of our solar system.

At the heart of this discovery is the Allende meteorite, a carbonaceous meteorite discovered way back in 1969. It's famously referred to as the "best-studied meteorite", but clearly it's nowhere near done revealing its secrets, as proven by this latest discovery.

The curium conundrum

When we see meteor showers streaking across the sky, it reminds us just how majestic and spectacular our solar system is. But while the layman may find them purely pretty, studying meteorites is key to understanding the formation and evolution of our solar system.

Researchers at the University of Chicago, while studying ceramic-like pockets embedded in the meteorite, discovered evidence that the meteorite once contained curium. It doesn't seem particularly amazing until you realise how crazy that is and the implications of it.

Curium is an element that was only discovered in 1944 when it was synthesised in a UC Berkeley lab. It's so unstable that it was only identified by its radioactivity. The first viable quantity of curium was only produced a few years later and even that isotope, curium-242, decays rapidly with a half-life of only 162 days!

With that level of instability, curium is only found in labs and in traces during nuclear explosions. Even its longest lasting isotope, curium-247, has a half-life of just over 15 million years, which means that any curium that formed at the birth of the universe would have long since decayed by now.

Thus, even though scientists have hypothesised since 1980 that heavy metal elements like curium may have been created at the beginning of the universe, their volatility meant that it was almost impossible to prove. Scientists have argued for and against its presence at the formation of the universe, with studies proving its existence and then subsequently being dismissed.

But there was a saving grace - curium-247 doesn't disappear, it decays into an isotope of uranium, uranium-235. But here too lay a problem: it's near impossible to distinguish regularly occurring uranium from curium-decayed uranium within a meteorite.

The Curious Marie

Luckily for the researchers at the University of Chicago, the ceramic piece of meteorite they were studying, which was older meteorite itself, held the answer.

These ceramic formations, known as ceramic inclusions, are mostly made of calcium and aluminium with only very minimal traces of uranium. Thus, anything more than trace amounts of uranium in these ceramic inclusions can only be explained by curium decay.

The Curious Marie had a seemingly paltry 6% more uranium than normal, but that's paltry only to laymen. To the researchers it was finally proof that these highly volatile elements were present at the beginning of the solar system, possibly as the product of exploding stars.

The curium, which would initially have been gaseous cooled with time, condensed and was trapped within the ceramic inclusions. By measuring the quantity of curium in the Curious Marie, the University of Chicago scientists were able to estimate the quantities in which curium existed in the early days of the solar system.

A sample of the Allende meteorite just showed that curium was present at the formation of our solar system

By comparing it with the quantities of other heavy radioactive elements like iodine and plutonium, the scientists speculate that all 3 could have been the product of a single cosmic event.

Nicholas Dauphas, one of the study's co-authors called the finding "particularly important" as it lets us know that "as successive generations of stars die and eject the elements they produced into the galaxy, the heaviest elements are produced together". This flies in the face of previous knowledge that suggested this wasn't the case.

The new knowledge gleaned from this finding can be incorporated into future models that look to understand the formation and evolution of our solar system.

Ranjan Crasta

Ranjan Crasta @jah_crastafari