Physicists have studied a 4.6 billion-year-old meteorite and found that it stores information about the state of the magnetic field of the nascent solar system at the time of the formation of the space guest. Since a lot of "heavenly stones" of this type have been accumulated, science has received a new channel of information about the physical conditions in the era of the formation of the solar system.
The achievement is described in a scientific article published in the journal Nature Communications by a team led by Jay Shah of the London Museum of Natural History.
Unfortunately, there are fewer sources of information about those distant events than scientists would like. Nevertheless, they are. For example, studying the chemical composition of comets helps to understand what the primary protoplanetary matter consisted of.
What about the magnetic fields that are believed to have played a significant role in the formation of the solar system as we know it? Here until today, everything was not at all smooth.
Of course, geologists have long known the property of some rocks to retain the magnetic field that affected them at the time of solidification. This phenomenon is used to recreate a picture of the Earth's ancient magnetosphere from samples for which there is dating, and vice versa, to determine the age of stones that have preserved a "record" of already dated geomagnetic conditions. However, in this case we are talking about uniformly magnetized ferromagnetic grains. Their ability to capture the original magnetization is described by Neel's well-proven relaxation theory. As for the unevenly magnetized inclusions, namely, they are found in meteorites, here terra incognita begins for physicists. Until now, no one could say whether they keep the magnetic record or have lost this information long ago.
When theorists lack knowledge, experiment comes to the rescue. Shah's team examined a meteorite containing olivine grains measuring tenths of a micrometer. The heavenly guest was heated to temperatures above 300 degrees Celsius. Using the latest techniques known as nanometer magnetic imaging and off-axis electron holography, scientists monitored the behavior of the magnetic field.
After processing the information received and performing numerical simulations, physicists came to an important conclusion: the time it takes for olivine grains to lose their initial magnetization (as experts say, the relaxation time) greatly exceeds the age of the solar system. This means that meteorites can be used as pages of the magnetic record.
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It is important that the examined stone is not an unthinkable rarity. It belongs to the class of chondrites, like 90% of all meteorites found by mankind. Therefore, before us is not a single whim of nature, but a new source of information about the distant past of the solar system.
“Our research shows that the magnetic fields that were present at the birth of the solar system are reliably preserved in the meteorite samples that we have in our collections,” Shah said on phys.org. "With a better understanding of these complex magnetizing structures, we can access this information about the magnetic field and understand how the solar system evolved from a disk of dust to the planetary system we see today."