Dynamics of material ejected from the Hatmehit depression and landslides on comet 67P/Churyumov-Gerasimenko

Abstract

In this work we investigate trajectories and regions of deposition of material ejected from depression Hatmehit on comet 67P/Churyumov-Gerasimenko. This depression, located on the lobe Head, could be a result of endogenic, possibly still ongoing, activity. We calculated trajectories of the ejecta with different initial velocities and we determined regions of their deposition. The gravitational field of comet 67P/CG is complex and its equipotential surfaces are dramatically different than its physical surface. Ejecta with the initial velocity ∼0.3 m s^-1 are deposited close to the starting points. For ∼0.6 m s^-1 a few regions of deposition are indicated. They cover significant areas but in the form of limited belt. These results are confirmed by observation. For ∼0.7 m s^-1 ejected material is more dispersed and deposits in large area, e.g., in the Imhotep region or even near Hatmehit after a comet lap. We also estimated the role of some non-gravitational forces.