"Cosmic Clock" Will Open the Way to Studying the Early Solar System: Scientists Have Studied the Composition of Ancient Meteorites

Russian scientists from GEOKHI RAS, in collaboration with American colleagues, conducted a study of the oldest fragments of the Solar System - refractory calcium-aluminum inclusions (CAIs) in meteorites. The key radioactive isotope aluminum-26 (26Al) was evenly distributed in the protoplanetary disk. This opens up the possibility of using it to date events that occurred in the early stages of planet formation.

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Aluminum-26 (with a half-life of about 700 thousand years) decays to form magnesium-26 (26Mg). This isotopic pair serves as a "cosmic clock." It allows determining the relative age of the oldest events in the history of the Solar System. However, for accurate dating, it was necessary to find out how evenly 26Al was distributed in the early stages.

Using the secondary ion mass spectrometry (SIMS) method, scientists measured the initial ratio of the isotopic pair 26Al/27Al in seven samples of refractory calcium-aluminum inclusions (CAIs).

The method allows determining the formation of objects over a very short interval - within hundreds of thousands of years after the formation of the very first objects. Dating the formation of components that make up meteorites is possible thanks to the radioactive pair 26Al-26Mg. The work is devoted to studying how evenly aluminum-26 is distributed in the Solar System in order to use it in cosmochronology.

Marina Ivanova, Doctor of Geological and Mineralogical Sciences, employee of the Laboratory of Meteoritics and Cosmochemistry of GEOKHI RAS

The results showed that six samples had an almost identical value - 5.2 × 10⁻⁵, which corresponds to the data from previous studies. Only one inclusion showed a slightly lower value, but within the margin of error. This confirms the hypothesis of a homogeneous distribution of aluminum-26 in the protoplanetary disk, which allows using its decay for accurate dating.

Experts also found that a large-scale event - evaporation and subsequent condensation of matter in the protoplanetary disk - led to the formation of CAIs precursors.

It is known that aluminum-26 entered the protoplanetary disk of the Earth as a result of "injection" of matter after a supernova explosion - outside the Solar System. Consequently, such studies allow us to gain knowledge about the processes that occurred in the earliest stages, and most importantly - about the time of formation of the first solid formations in the Solar System.

Marina Ivanova, Doctor of Geological and Mineralogical Sciences, employee of the Laboratory of Meteoritics and Cosmochemistry of GEOKHI RAS

Earlierwww1.ru reported that solar flares and magnetic storms willcontinue until 2027.