Program: GN-2017B-Q-40

One of the most important longstanding questions in planet formation is: what, if any, role does gravitational instability (GI) in disks play in producing the observed population of giant planets? To address this question, we have identified several systems with known transiting or radial velocity planets or low-mass brown dwarfs on orbits < 1 AU, that nonetheless have properties typical of objects predicted to form via gravitational instability at wide separation (> 30 AU). If these are indeed GI planets then the most likely manner in which they have attained their currents orbits is via scattering followed by tidal circularisation. Kozai scattering models, however, clearly predict that these systems should also possess additional massive companions at wide separations. Therefore, we propose to search for these companions with direct imaging, allowing a clear test for models of planet formation by disk driven gravitational instability.