December 1, 2020

The Solar System was formed in less than 200,000 years


An artist's conception of the dust and gas surrounding a newly formed planetary system.

An artist’s conception of the dust and gas surrounding a newly formed planetary system.
POT

A isotope analysis in molybdenum found in meteorites reveals that our Solar system was formed in the short time of 200,000 years, about 4.5 billion years ago.

The material that makes up the sun and the rest of the solar system came from collapse of a large cloud of gas and dust about 4.5 billion years ago. By looking at other star systems that formed in a similar way to ours, astronomers estimate that it probably takes between 1 and 2 million years for the collapse of a cloud and the ignition of a star, but this is the first study that can provide figures about our own solar system.

“Previously, the formation time frame was not really known for our solar system,” said LLNL (Lawrence Livermore National Laboratory) cosmochemist Greg Brennecka, lead author of a paper that appeared in Science. “This work shows that this collapse, which led to the formation of the solar system, happened very quickly, in less than 200,000 years. If we scale all of this to a human lifespan, the formation of the solar system would be compared to a pregnancy which lasts about 12 hours instead of nine months. This was a quick process. ”

The oldest dated solids in the solar system are calcium- and aluminum-rich inclusions (CAI), and these samples provide a direct record of the formation of the solar system.

These micrometer to centimeter inclusions in meteorites were formed in a high temperature environment (more than 1300 Kelvin), probably near the young sun. They were then transported to the region where carbonaceous chondrite meteorites (and their parent bodies) formed, where they are found today. Most CAIs were formed 4.567 million years ago, over a period of approximately 40,000 to 200,000 years.

This is where the LLNL team comes in. The international team measured the molybdenum (Mo) isotopic and trace element compositions of a variety of CAIs taken from carbonaceous chondrite meteorites, including Allende, the largest carbonaceous chondrite found on Earth. Because they found that the different Mo isotopic compositions of the CAIs cover the entire range of material that formed in the protoplanetary disk rather than just a small portion, these inclusions must have formed within the time span of the cloud collapse. .

Since the observed time span of stellar accretion (1-2 million years) is much longer than it took for CAIs to form, the team was able to determine which astronomical phase in the formation of the solar system was recorded by CAI formation, and ultimately how quickly the material that makes up the solar system increased.

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