Solve a paradox to uncover key clues to the history of our solar system

New clues lead to a better understanding of the evolution of the solar system and of the origin of Earth as a habitable planet.

In a new article published in the journal Nature Communications Earth and environment, researchers at the University of Rochester were able to use magnetism to determine, for the first time, when carbonaceous chondrite asteroids – water-rich asteroids and amino acids– first arrived in the internal solar system. The research provides data that helps inform scientists about the early origins of the solar system and why some planets, like Earth, became habitable and were able to maintain conditions suitable for life, while other planets, such as March, does not have.

The research also provides scientists with data that can be applied to the discovery of new exoplanets.

“There is a particular interest in defining this story – with reference to the large number of exoplanet discoveries – to infer whether events might have been similar or different in exo-solar systems, ”says John Tarduno, William R. Kenan, Jr., professor in the Department of Earth and Environmental Sciences and Dean of research for the arts, sciences and engineering in Rochester. “This is another element of the search for other habitable planets.”

Solve a paradox using a meteorite in Mexico

Some meteorites are pieces of debris from space objects such as asteroids. After separating from their “parent bodies”, these parts are able to survive by passing through the atmosphere and eventually hitting the surface of a planet or moon.

Studying the magnetization of meteorites can give researchers a better idea of ​​when objects formed and where they were early in the history of the solar system.

“We realized several years ago that we could use the magnetism of meteorites derived from asteroids to determine how far these meteorites were from the sun when their magnetic minerals formed,” Tarduno says.

In order to learn more about the origin of meteorites and their parent bodies, Tarduno and the researchers studied magnetic data collected from the Allende meteorite, which fell to Earth and landed in Mexico in 1969. The meteorite Allende is the largest carbonaceous chondrite meteorite found on Earth and contains minerals – calcium-aluminum inclusions – believed to be the first solids formed in the solar system. It is one of the most studied meteorites and has been regarded for decades as the classic example of a meteorite originating from a primitive asteroid parent body.

In order to determine when the objects formed and where they were found, the researchers first had to address a meteorite paradox that confused the scientific community: How did meteorites gain in magnetization?

Recently, a controversy erupted when some researchers proposed that carbonaceous chondrite meteorites like Allende had been magnetized by a core dynamo, like that of Earth. The Earth is known as a differentiated body because it has a crust, mantle, and core separated by composition and density. At the beginning of their history, planetary bodies can gain enough heat that there is widespread fusion and the dense material – iron – flows towards the center.

New experiments by Rochester graduate student Tim O’Brien, the first author of the article, revealed that the magnetic signals interpreted by previous researchers did not actually come from a nucleus. Instead, O’Brien discovered that magnetism is a property of Allende’s unusual magnetic minerals.

Determine the role of Jupiter in the migration of asteroids

Having resolved this paradox, O’Brien was able to identify meteorites with other minerals capable of faithfully recording the first magnetizations of the solar system.

Tarduno’s magnetism group then combined this work with theoretical work by Eric Blackman, professor of physics and astronomy, and computer simulations led by graduate student Atma Anand and Jonathan Carroll-Nellenback, a computer scientist at the Rochester laboratory for laser energy. These simulations showed that the solar winds enveloped the first bodies of the solar system and that it was this solar wind that magnetized the bodies.

Using these simulations and data, the researchers determined that the parent asteroids from which the carbonaceous chondrite meteorites detached themselves arrived in the asteroid belt of the Outer Solar System around 4,562 million years ago, during of the first five million years in the history of the solar system.

Tarduno says that the analyzes and modeling provide more support for the so-called big tack theory of movement of Jupiter. While scientists once believed that planets and other planetary bodies were formed of dust and gas at an ordered distance from the sun, scientists today realize that the gravitational forces associated with giant planets, such as Jupiter and Saturn—May cause the formation and migration of planetary bodies and asteroids. The big turn theory suggests that the asteroids were separated by the gravitational forces of the giant planet Jupiter, whose subsequent migration then mixed the two groups of asteroids.

He adds: “This early movement of carbonaceous chondrite asteroids sets the stage for a further dispersal of water-rich bodies – potentially towards Earth – later in the development of the solar system, and it may be a common pattern for all of them. exoplanet systems.

Reference: “Arrival and magnetization of carbonaceous chondrites in the asteroid belt before 4562 million years” by Timothy O’Brien, John A. Tarduno, Atma Anand, Aleksey V. Smirnov, Eric G. Blackman, Jonathan Carroll-Nellenback and Alexander N. Krot, December 4, 2020, Earth and environment communications.
DOI: 10.1038 / s43247-020-00055-w