42 of the Solar System’s biggest asteroids revealed in glorious new images

If there’s one thing our solar system doesn’t lack, it’s rocks.

Small rocks, big rocks, dry rocks, icy rocks. Rocks that are like the other rocks. This is really the system of rocks – we happen to live here too. Despite all their prevalence, however, these rocks are not easy to see; they are small, dark, and overshadowed by larger, brighter objects.

But we’re getting better, and now we have the most detailed examination yet of some of the largest rocks in the solar system that aren’t planets. An international team of astronomers used the European Southern Observatory’s Very Large Telescope to image 42 of the largest objects lying around the asteroid belt between March and Jupiter.

“Only three large Main Belt asteroids, Ceres, Vesta and Lutetia, have been photographed in high level of detail so far, as they have been visited by NASA and the Agency’s Dawn and Rosetta space missions. space, respectively “, says astronomer Pierre Vernazza of the Laboratory of Astrophysics of Marseille in France.

“Our ESO observations provided sharp images for many more targets, 42 in total.”

rock encrustationThe 42 asteroids. Click here to see the image in full size. (ESO / M. Kornmesser / Vernazza et al. / MISTRAL / ONERA / CNRS algorithm)

We have already had a preview of the images. Last month, researchers revealed the best images yet of a particular dog bone-shaped asteroid named Cleopatra. The data revealed that Cleopatra’s two moons may have formed from the dust ejected by the asteroid itself.

The new work is much more radical, designed to examine the collective properties of these objects, rather than their individual characteristics, with new 3D data helping to reveal the shape and mass of these mysterious asteroids. Basically, objects fall into two categories: those that are almost round; and those who are more elongated, Cleopatra being the most extreme example of the latter.

Interestingly, these categories are not divided based on size. Ceres, the largest object probed in the survey with a diameter of 940 kilometers (584 miles), is fairly round. Vesta, the second largest at 520 kilometers, has a more uneven shape. Flora and Adeona, 146 and 144 kilometers away respectively, are also quite round. Sylvia, 274 kilometers away, is lying down.

The new 3D data also gave researchers much better constraints on the volumes of the 42 objects. Once you know the volume and mass of an object, you can calculate its density and deduce its composition. Again, there was a wide range in the sample.

The density of the Earth, for context, is 5.51 grams per cubic centimeter. The less dense asteroids had densities of around 1.3 grams per cubic centimeter, roughly the same density as coal, suggesting a carbonaceous and porous composition. The densest were Psyche and Kalliope, with densities of 3.9 and 4.4 grams per cubic centimeter respectively, which is denser than diamond, suggesting a stony iron composition.

attachA poster of the 42 asteroids and their orbits. Click here to see the image in full size. ESO / M. Kornmesser / Vernazza et al. / MISTRAL / ONERA / CNRS algorithm)

This suggests that the objects in the asteroid belt likely originated from different parts of the solar system before ending up where they are now, the researchers said.

“Our observations provide a solid support for a substantial migration of these bodies since their formation”, said astronomer Josef Hanuš from Charles University in the Czech Republic.

“In short, such an enormous variety in their composition can only be understood if the bodies originate from distinct regions of the solar system.”

There is a lot we still don’t know, however. We have samples of asteroids here on Earth, fragments that shattered and ended up here as meteorites, which allows us to make some inferences about the compositions of space rocks. Some of the higher density objects, however, may not have analogues available, making determining their composition more difficult.

Additionally, we currently cannot see small asteroids in detail, which means we are operating with an incomplete data set. Once we have this information, we can better assess which asteroids we should send future space probes to visit. For this, the team is basing its hopes on the next extremely large telescope, which should begin operations in a few years.

“ELT observations of main belt asteroids will allow us to study objects up to 35 to 80 kilometers in diameter, depending on their location in the belt, and craters about 10 to 25 in size. kilometers “, Vernazza said.

“Having a SPHERE-type instrument at the ELT would even allow us to image a similar sample of objects in the distant Kuiper Belt. This means that we will be able to characterize the geological history of a much larger sample of small soil bodies. . “

Rock n Roll.

The research was published in Astronomy & Astrophysics.

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