“So far, we have only been able to detail three large main belt asteroids – Ceres, Vesta and Lutetia, which have been visited by NASA’s Dawn and Rosetta space missions and the European Space Agency, respectively,” said Pierre Vernazza, who led the new research. Studies was published in the journal Astronomy & Astrophysics.
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It is how few asteroids so far astronomers have described in detail that prevent scientists from better understanding their key properties. For example, they lacked information about what their three-dimensional form looked like or what their density was.
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Therefore, in 2017, Vernazza and his team decided to fill this gap by thoroughly researching the main bodies in the asteroid belt. The research lasted more than three years.
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Most of the 42 objects in their catalog are larger than 100 kilometers; specifically, the team viewed almost all asteroids in a strip larger than 200 kilometers – it succeeded in 20 of the 23 objects.
The two largest objects the team examined were Ceres and Vesta, which have an average of about 940 and 520 kilometers. By contrast, the two smallest asteroids are Urania and Ausonia, each only about ninety kilometers in diameter.
By reconstructing the shapes of the objects, the team found that the observed asteroids are usually divided into two families. Some are almost perfectly spherical, such as Hygiea and Ceres, while others have a less regular, “elongated” shape – the most bizarre among them is the asteroid Cleopatra, which reminds astronomers of a dog bone.
Between coal and diamond
By combining the shapes of the asteroids with information about their masses, the team found that the density of these bodies varied considerably. The least dense asteroids Lambert and Sylvia have a density of about 1.3 grams per cubic centimeter, which corresponds to coal. Psyche and Kalliope, on the other hand, are the densest, reaching a density of 3.9 and 4.4 grams per cubic centimeter, respectively, which is more than the density of a diamond.
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