Brightness variations on the surface of '67P / Churyumov' show the complexity of cometary activity

An international team, with the participation of the Institute of Astrophysics of Andalusia (IAA-CSIC), has observed with the OSIRIS camera onboard the Rosetta mission changes in light reflected on the surface of comet 67P / Churyumov with different time scales, from minutes to several days. These changes in brightness are mainly due to the amount of ice present in the observation area. This finding, published in the journal Science, helps to construct models to simulate cometary activity and, therefore, to advance in the understanding of the formation of the Solar System.

The bright variations on the 67 P / Churyumov surface are due, on the one hand, to the heterogeneity of the composition of the comet, which exposes extensions of ice when the dust that covers it is expelled from the nucleus; and, on the other hand, to the existence of the so-called water cycle, recondensation of water molecules in cold areas of the surface (areas at night or in shade). These observations have been carried out by measuring the relative brightness of the comet surface using different OSIRIS filters with high spatial and temporal resolution.

"Cometary activity, that is, how gas and dust are released from the comet nucleus, was one of the least known processes in its nature. Our study provides key information to create models for interpreting the gas and dust production of comets", explains Pedro J. Gutiérrez, researcher at the Institute of Astrophysics of Andalusia (IAA-CSIC) who participates in the study.

One of the main objectives of the Rosetta mission was to provide quality data that would serve as a reference for studying and analyzing the large amount of data being taken from Earth. "This work has succeeded. And the information it offers us is key not only to know the development of cometary activity but to understand how our Solar System was formed from the collapse of an interstellar cloud of gas and dust", concludes Gutiérrez.