Computer exam | Clearest images of 42 largest objects in the asteroid belt revealed

The European Southern Observatory (ESO), located in Chile, using the Very Large Telescope (VLT) instrument has detected images of 42 of the largest asteroids. is located in the asteroid belt located between the orbits of Mars and Jupiter. “Never before has such a clear image of such a large group of asteroids been obtained. Observations show a wide variety of unusual shapes, ”ESO said in a statement. These more detailed observations help scientists trace the origins of asteroids in the solar system.

“To date, only highly detailed images of three large main-belt asteroids – Ceres, Vesta and Lutetia – have been captured by NASA’s Dawn and ESA Rosetta spacecraft,” explains Pierre Vernazza of the Space Research Laboratory. The astrophysicist from Marseille, France, who led this study, published in the journal Astronomy and astrophysics… “Our observations now show very clear images of many other objects, 42 objects in total.”

Between 2017 and 2019, Vernazza and his team surveyed the major bodies of the asteroid belt to solve the problem of missing important details such as the three-dimensional shape or density of asteroids. “Most of 42 objects this sample has a dimension of more than 100 km; in particular, the team photographed virtually all asteroids in the belt over 200 km in size, that is, 20 out of 23. The two largest objects observed were Ceres and Vesta, with a diameter of about 940 and 520 km, respectively, and the smallest were Urania and Ausonia– both are only 90 km, ”explains ESO.

These observations also allowed the team to understand that the observed asteroids are essentially divided into two groups, the team explained. Some of them are almost perfectly spherical, for example Hygiene and Ceres, others have more unusual shapes such as Cleopatra, which, according to scientists, has the shape of a “dog bone”. After combining information regarding the shape and mass of the asteroids, the team further realized that the density varied significantly across the entire sample, thus concluding that the four least dense asteroids, including Lambert and Sylvia, have a density of about 1.3 grams per cubic centimeter, which is about the same density as coal, while denser ones such as Psyche and Calliope, have a density of 3.9 and 4.4 g / cm³correspondingly higher than the density of diamond. Thus, a large difference in signal density suggests that the composition of the asteroids is changing.

“Our observations convincingly confirm the significant migration of these bodies after their formation. In short, this diversity in their composition can only be understood if the bodies originated in different regions of the solar system, ”explains Josef Hanusz from Charles University in Prague, Czech Republic, one of the authors of the study. Thus, these results support the theory that less dense asteroids formed in distant regions of the solar system, beyond the orbit of Neptune, and then migrated to their current position.

These results are made possible by the tool SPHERE (Study of spectro-polarimetric high-contrast exoplanets), juntamente com o VLT ESO. “The improved capabilities of SPHERE, coupled with the fact that little is known about the shape of the largest asteroids in the main belt, have allowed us to make significant progress in this area of ​​research,” says co-author Laurent Jorda. also from the University of Astrophysics of Marseille.

with the future Extremely large telescope (ELT) of ESO under construction in Chile, astronomers expect to get even more detailed images of bodies in the asteroid belt. The ELT is expected to be operational by the end of this decade. “ELT observations of asteroids in the main belt will allow us to study objects with a diameter of 35 to 80 km, depending on their location in the belt, and craters with sizes from about 10 to 25 km,” says Vernazza. “Also, if we have a tool like SPHERE installed on the ELT, we might even be able to get images of a set of similar objects, but located in the far Kuiper belt! In this way, we were able to characterize from scratch the geological history of a much larger sample of small bodies.…“, he adds.