An article published in the journal “Nature Astronomy” describes a research that offers new clues about the comet 67P/Churyumov-Gerasimenko’s formation. A team led by Stephen Schwartz of the University of Côte d’Azur and the University of Arizona conducted a series of computer simulations to study the formation of comets like this one, formed by two lobes, expanding previous studies confirming them and offering an explanation to some of its characteristics.
The mission of ESA’s Rosetta space probe ended at the end of September 2016 with a huge amount of data collected on the comet 67P/Churyumov-Gerasimenko. Its shape, consisting of two lobes connected by a neck, has been the subject of studies since it was recognized and over time a lot of evidence have been provided of the fact that it’s due to the merger of two smaller comets.
For some time scientists thought that the merger took place about 4.5 billion years ago but in November 2016 two articles published in the journal “Astronomy & Astrophysics” proposed a different theory, in which “Chury” was significantly younger. Martin Jutzi of the University of Bern, Switzerland, one that research’s lead authors, was also part of the team that extended it.
New computer simulations allowed to obtain new information on the consequences of collisions between comet nuclei. They can get fragmented and then most of the pieces coalesce into smaller objects. The new nuclei have different sizes and shapes and can be elongated and formed by two parts, just like the comet 67P/Churyumov-Gerasimenko.
An important result of these simulations is that only a small part of the materials gets remarkably compressed and heated. Generally, the consequence is that those materials are ejected so they don’t accumulate together with those that kept their original characteristics virtually intact. On the side opposite the impact, the volatile compounds can withstand violent collisions, therefore the new nuclei maintain a considerable quantity of them.
Compared to previous studies, these new simulations also tested the possible consequences of impacts at speeds of several kilometers per second. The result is that the fragments of the comets that collide still start merging again after just a few hours.
These new simulations also explain the presence of formations found on the comet 67P/Churyumov-Gerasimenko such as pits. Their formation was a mystery but a layered structure could explain them because the accumulation of large blocks could leave that kind of cavities.
In essence, the study of the comet 67P/Churyumov-Gerasimenko keeps on being extremely interesting, offering new clues to the history of the solar system. Chury’s materials retained their original characteristics providing data on the initial phase of the solar system’s formation and at the same time it’s increasingly likely that its shape is the result of much later events.