A team of astronomers, thanks to the VLT telescope of the European Southern Observatory (ESO) in Chile, has obtained images of 42 of the largest objects in the world. asteroid belt, located between Mars and Jupiter.
According to experts, such sharp images have never been obtained of such a large group of asteroids. The observations revealed a wide range of curious shapes, from spherical to some similar to dog bones, that help researchers trace the origins of asteroids in our country. Solar system.
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For ESO, the detailed images of these 42 objects constitute a breakthrough in asteroid exploration, thanks to ground-based telescopes, and contribute to answering fundamental questions about life or the universe.
Until now, only detailed images had been obtained of three large main belt asteroids, Ceres, Vesta and Lutetia, which were visited by the Dawn and Rosetta space missions of the Pot and of the European Space Agency (ESA), respectively, explains Pierre Vernazza.
“Our observations at ESO have provided sharp images for many more objects, 42 in total,” adds Vernazza, from the Marseille Astrophysics Laboratory, who led this study that publishes Astronomy and Astrophysics.
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Due to the small number of detailed asteroid observations, key features, such as their 3D shape or density, have remained largely unknown.
Between 2017 and 2019, Vernazza and his team set out to fill this gap by conducting a comprehensive study of the main bodies in the asteroid belt, ESO said in a statement. Most of the 42 objects in the sample are larger than 100 kilometers.
The team, including Spanish scientists, analyzed the two largest objects, Ceres and Vesta, whose diameter is estimated at 940 and 520 kilometers, while the two smallest asteroids turned out to be Urania and Ausonia, which measure about 90 kilometers .
By reconstructing their shapes, the team discovered that the observed asteroids are mainly divided into two families. Some are almost perfectly spherical, such as Hygiea and Ceres, while others have a more peculiar, “elongated” shape, with the “dog bone” asteroid called Cleopatra as the “undisputed protagonist”, details the ESO.
By combining the shapes with information about their masses, the team found that the densities vary significantly across the samples. The four least dense asteroids studied, including Lamberta and Sylvia, have densities of about 1.3 grams per cubic centimeter, roughly the density of carbon.
Psyche and Kalliope have the highest density, at 3.9 and 4.4 grams per cubic centimeter, respectively, which is higher than the density of diamond (3.5 grams per cubic centimeter). This large difference suggests that the composition of asteroids varies significantly, offering important clues to their origin.
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“Our observations offer strong evidence of a substantial migration of these bodies since their formation. In summary, the enormous variety in composition can only be understood if the bodies originated in different regions of the Solar System”, explains Josef Hanus, from Karlova University, Prague
The results support the theory that less dense asteroids formed in remote regions outside of Neptune’s orbit and migrated to their current location.
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