A piece of ancient space rock that ended up on Earth is giving scientists the clues they need to understand the dust cloud from which the solar system was born.
The rare object is known as Erg check 002One of the isotopes in it indicates the presence of radioactive material scattered from recently exploded stars filling our solar system at the end of its formation.
It’s a fascinating glimpse into the solar environment billions of years ago, and not only shows how meteorites can act as time capsules preserving secrets of the past, but those secrets can then be used to better understand what we find in other space rocks.
The sun, like all stars, was born from gas and dust. The solar nebula was a dense cloud floating in space, with a denser region collapsing under gravity to form a young star, coalescing into more and more material as it rotated and grew. Once the sun had swallowed its fill, the remaining disk of matter entered into planet formation.
We have a rough idea of what was in the nebula. After all, our planet, and all the other planets and rocks and dust drifting through the solar system, were formed from it. But in many of those places, a lot has changed chemically over the 4.6 billion years or so since the sun was just a blip in a cloud of dust.
By contrast, meteorites and asteroids are thought to represent a relatively primitive sample of the solar system at the time these bodies formed, since they have remained virtually unchanged or changed since then. So we can study them to find out when they were formed, and the composition of the material from which they were formed.
This brings us back to Erg Chech 002, a meteorite older than Earth Unmatched. It was discovered in 2020 in I want a check In the Sand Sea in southwestern Algeria, the stone has an unusual andesitic composition associated with volcanic activity, suggesting that the object was once part of an early-forming planet, whose evolution was stopped early.
One of the elements it contains is a stable isotope of magnesium called magnesium-26. Magnesium 26 is decay product of a particular radioactive isotope of aluminium, aluminum-26which are produced during the violent supernovae death of massive stars.
Aluminum 26 has a relatively short lead half life to 717,000 yearsHowever, the products of its decay can be used to infer its previous existence in materials, and to calculate the age of the objects in which they are found.
Now a team of scientists led by cosmologist Evgeny Kristianinov of the Australian National University in Australia has used this isotope clock to infer the distribution of aluminum-26 in the solar nebula.
They calculated the meteorite’s age, based on the proportions of its radioactive decay products. Their calculations were consistent with previous calculations for the age of Erg Chech 002 – 4.566 billion years.
Next, the team compared it with other ancient, well-preserved meteorites with a similar rock composition. They found that Erg Chech 002 contained significantly more aluminum-26 than other meteorites, a result which they interpreted to mean that aluminum-26 was unevenly distributed across our solar nebula.
They believe the findings represent a late fall of stellar material into the solar nebula, bringing with it newly formed radioactive isotopes, including aluminum-26 that was transported to the nascent planet from which Erg Chech 002 came.
Previous research indicates that the nascent solar system was flooded with radioactive material from supernova explosions during the birth of the sun. Kristianinov and his colleagues’ work represents another piece of the puzzle at this strange time in our ancient history.
The research has been published in Nature Communications.