Scientists explained the origin of the mysterious iron meteorites. They preserved the traces of the magnetic field, which in ancient times was created by the liquid core of their parent body.
Meteorites falling on the planet, are fragments of the earliest bodies formed in the early Solar system and not incorporated into planets or other large objects. The most common meteorites are chondrites — the composition is virtually no different from the Sun (except hydrogen and helium), their stuff didn’t even survive the melting and solidification and billions of years has remained virtually unchanged. In contrast, chondrite passed through the melting and close to terrestrial basalts.
There are iron meteorites that could have formed from magma, and possibly from the metallic core of the ancient body. Enough to it was massive and had to undergo differentiation — the separation of structural layers: the crust, mantle and core. But iron meteorites are a rare group of IEE contain a mixture of both past and not past the melting minerals and, of course, iron.
It is believed that their source is a large asteroid Hebe. Its mineral and isotopic composition coincides with many found on Earth and IEE chondrites-meteorites (some of them even include water and organics).
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It is assumed that at the dawn of its existence, it was a differentiated body with a crust, mantle and core — planetesimals, “germ”, which failed to grow into a full-fledged planet. Moreover, the core can be a liquid and even to generate a magnetic field, similar to what is observed on Earth. About it is told in a new article published in the journal Science Advances.
The team of Professor Massachusetts Institute of technology (MIT) Benjamin Weiss (Benjamin Weiss) used synchrotron x-ray radiation of the accelerator BNL to consider the magnetization of iron particles in samples of meteorites IEE. And indeed, many of them preserve the total orientation you received in the molten state.
Scientists estimate that the power source of the magnetic field could reach several tens of microtesla, which is comparable with the global magnetic field of the Earth. To create such a field core of semi-liquid should reach at least several tens of kilometers in diameter. IEE-meteorites could have formed from material that solidified under the influence of its magnetic field.
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The authors ‘ simulations confirm that planetesimal with a liquid core could survive a collision that knocked part of the rich iron substance from the core closer to the surface. Here it can freeze, and the iron particles were recorded in the orientation of the magnetic field lines. Then could get many millions, even billions, of years: planetesimal did not become the planet cooled and the core is frozen and no longer create a magnetic field. However random shocks continue to beat him with the fragments falling to the Ground in the form of rare iron meteorites of the group of IEE.