WASHINGTON (Reuters) – A new way to study planets in other solar systems – doing a kind of planetary wreck autopsy devoured by a type of star called the white dwarf – is showing that rocky worlds with Earth-like geochemistry can be quite common in the cosmos. .
An artist's depiction shows a star called a white dwarf with a planet (top right) and material in orbit around the star. Courtesy of Mark Garlick / UCLA / Leaflet via REUTERS.
In a study published on Thursday, the researchers studied six white dwarfs whose strong gravitational force had sucked crushed debris from planets and other orbiting rock bodies. They found that this material was very similar to what is present on rocky planets like Earth and Mars in our solar system.
Given that Earth is home to an abundance of life, the findings offer the latest tantalizing evidence that planets equally capable of hosting life exist in large numbers beyond our solar system.
"The more we find common ground between planets made in our solar system and those around other stars, the more likely it is that Earth is not uncommon," said Edward Young, professor of geochemistry and cosmo-chemistry at the University of California, Los Angeles. . (UCLA), who helped lead the study published in the journal Science. "The more Earth-like planets, the greater the chances of life as we understand it."
The first planets beyond our solar system, called exoplanets, were seen in the 1990s, but it has been difficult for scientists to determine their composition. Studying white dwarfs offered a new avenue.
A white dwarf is the burned nucleus of a sun-like star. In its agony, the star explodes from its outer shell and the rest collapses into an extremely dense, relatively small entity that represents one of the densest forms of matter in the universe, surpassed only by neutron stars and black holes.
Planets and other objects that once orbited can be ejected into interstellar space. But if they deviate from the huge gravitational field, "they will be ground to dust, and that dust will begin to fall on the star and disappear from sight," said author Alexandra Doyle, a student of geochemistry and astro-chemistry at UCLA. .
"That's where the idea of" autopsy "comes from," Doyle added, noting that by observing the elements of the massacred planets and other objects within the white dwarf scientists, they can understand their composition.
The researchers observed a fundamental feature of rocks: their oxidation state. The amount of oxygen present during the formation of these rocks was high – just as it was during the formation of the rock material in our solar system. They focused on iron, which when oxidized ends up as rock.
"Rocks are rocks, even when they form around other stars," said Young.
The closest of the six white dwarf stars is about 200 light years from Earth. The farthest is about 665 light years away.
Will Dunham report; Editing by Sandra Maler
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