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Debris in extrasolar planetary systems

Final Report Summary - DEBRIS (Debris in extrasolar planetary systems)

This project involved the study of the debris disks of nearby stars, i.e. the asteroids, comets, dust and gas that surround the stars. The project provided an unbiased census of the nearest stars to the Sun, using surveys with the most recently commissioned astronomical observatories to search for signs of this debris (e.g. with the Herschel Space Observatory and the Large Binocular Telescope Interferometer). When debris was found to be present, further observations were used to characterise the structure and composition of the debris disks (e.g. using the James Clerk Maxwell Telescope and the Atacama Large Millimeter Array).

Since these observations probed previously unexplored physics, new modelling techniques were developed in the course of the project with which to interpret these observations. These models involved the dynamical interaction between the debris and planets and stars, collisions amongst the debris, and the evolution of the gaseous component. Modelling of the debris disk images was used to gain an insight into the planetary systems also thought to be orbiting these stars, both in terms of where there may be planets today, and how those planets formed and evolved. A correlation between the presence of debris and low-mass planets was discovered emphasising the connection between these two components of the planetary system. The project also demonstrated how debris disk structure is strongly influenced by the presence of other stars in the system, and elucidated the links between the cold (outer) and hot (inner) regions of debris disks. The unexpected discovery of gas in many debris disk systems was used to show that the planetesimals in these disks have a similar composition to comets in the Solar System.

As well as having a significant impact on the field of debris disks, the project also had a broader impact on the study of extrasolar planets, planet formation and protoplanetary disk evolution.