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Dissipation in Self-gravitating aggregates

Presentation #320.01 in the session Asteroid Dynamics (iPosters).

Published onOct 20, 2022
Dissipation in Self-gravitating aggregates

In this research work we investigate how a self-gravitating aggregate dissipates energy following an impact or other perturbation that excites motion in its components. We investigate the outcome using two methods of excitation: 1. by an impact and, 2. by the random agitation of their particles. For the impact we take the DART mission and the Didymos system as a template for a binary system and the parameters of an impactor. For the impactor we take one ~10m particle and provide it with the same momentum of the S/C (collision is always head-on). Then, we vary the speed for different impacts so that the momentum is constant. For agitation, we calculate the escape velocity of the simulated Dimorphos secondary and provide the particles with a random velocity, whose speed is just a fraction of the escape speed. We do this to study how different levels of energy are dissipated which is akin to the different impact speeds we also simulated.

We find that there are marked differences in how energy is dissipated depending on the method of excitation, though in general most of the excess energy is dissipated within a few minutes. Also impacts usually change the shape of the aggregate which produces different levels of libration and there seems to be correlation between the amount of energy the impactor has and how much momentum is transmitted. Agitation on the other hand, allows the particles to re-accommodate and reshape the aggregate to get closer to a stable shape. These and other effects will be analyzed at the conference.

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