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Meteorite diamonds ‘came from lost planet’

UNITED STATES (OBSERVATORY) –¬†Approximately 4.5 billion years ago, when the solar system was in its infancy, many protoplanets rotated around our star . By this term astronomers designate large embryos in the protoplanetary disk that have passed the stage of internal melting, that is, having formed subsoil.

Many of the protoplanets merged and formed larger celestial bodies, while others did not withstand collisions and lost the battle for a place near the Sun.

Such cosmic road accidents led to the formation of an infinite number of carbon-rich asteroids. And one of them made a trip to Earth, eventually showering it with amazing meteorites.

This scenario was described by an international team of scientists after studying the unique debris found in the Nuba desert in Sudan in 2008. These meteorites were formed during the explosion of the asteroid 2008 TC 3 with a diameter of two to five meters. The explosion occurred at an altitude of about 40 kilometers above the surface of the planet.

True, only 0.005% of the original mass of the asteroid was collected. Fragments accumulated several hundred, and the experts gave them a common name: the meteorites of Almahata Sitta ( Almahata Sitta ).

Researchers from Switzerland, France and Germany conducted a grandiose work on the study of space “aliens”. The authors were interested not only in their age, but also in the composition of the samples. They very quickly realized that before them the ureilites are a rare type of a stone meteorite that has a unique mineralogical composition.

Ureilites contain a high percentage of carbon in the form of graphite and diamonds. As a rule, we are talking about nanodiamonds (less than a micrometer in diameter), but in this case, researchers were surprised to find diamonds up to a diameter of one hundred micrometers.

This feature also helped the team to make an assumption about the origin of the meteorites of Almahat Sitt. The diamonds found in the African israelites are at least a hundred times larger than the diamonds formed in the collision of celestial objects. Significantly superior to these and diamonds, which are formed by the condensation of carbon vapors inside clouds of interplanetary gas and dust (such diamond rains are, for example, on Saturn and Jupiter ).

There remains the only possibility: the diamonds were already in the bowels of the protoplanet, when a “big boom” occurred (by the way, they formed at least 4.55 billion years ago).

One of the authors of the work of geophysicist Philippe Gillet from the Federal Polytechnic School of Lausanne (Switzerland) explains that such large diamonds simply could not have formed as a result of the impact, rather they are the result of geophysical processes taking place on a protoplanet.

Using transmission electron microscopy, X-ray spectroscopy, and other methods, experts have found that there are small grains of iron-rich sulfides inside the diamond, as well as many other mineral inclusions (chromites, phosphates).

The team estimated that the formation of such diamonds requires a pressure of 200,000 bar. Hence the conclusion about the dimensions of the protoplanet: the comparison with Mercury would be the best, but it is possible that the heavenly body could be compared even with Mars. And the formation of diamonds occurred closer to its center or literally on the boundary of the metal core.

Paleontologists note: the fact that the solar system in youth was, let’s say, more numerous, has not been news for a long time. Moreover, with respect to some of its planets, there are very interesting and well-founded hypotheses (for example, that the protoplanet named Thea had once crashed into the young Earth, and the wreckage after this catastrophe merged into a body that became a satellite of the Earth , that is, the Moon).

“We have in our hands the remains of this first generation of planets, which are no longer there, because they were destroyed or merged into a more massive planet,” adds Gillet.

The find made in the Nuba desert, one step closer brings astronomers and geophysicists to understand what the solar system was at the very beginning of the path and what processes were taking place in it, the scientist concludes.

More details about the study of the rarest ureilites are described in an article published in the journal Nature Communications.

Recall that in the meteorite fragments also found an unknown “impossible” crystal and the most abundant mineral on the Earth.