arXiv subjects

Erik Asphaug

Publications and source records attributed to Erik Asphaug.

39 records · Page 3Linked to original sources

arXiv2015

Global Scale Impacts

Global scale impacts modify the physical or thermal state of a substantial fraction of a target asteroid. Specific effects include accretion, family formation, reshaping, mixing and layering, shock and frictional heating, fragmentation, material compaction, dilatation, stripping of mantle and crust, and seismic degradation. Deciphering the complicated record of global scale impacts, in asteroids and meteorites, will lead us to understand the original planet-forming process and its resultant populations, and their evolution in time as collisions became faster and fewer. We provide a brief overview of these ideas, and an introduction to models.

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arXiv2015

Collisional Formation and Modeling of Asteroid Families

In the last decade, thanks to the development of sophisticated numerical codes, major breakthroughs have been achieved in our understanding of the formation of asteroid families by catastrophic disruption of large parent bodies. In this review, we describe numerical simulations of asteroid collisions that reproduced the main properties of families, accounting for both the fragmentation of an asteroid at the time of impact and the subsequent gravitational interactions of the generated fragments. The simulations demonstrate that the catastrophic disruption of bodies larger than a few hundred meters in diameter leads to the formation of large aggregates due to gravitational reaccumulation of smaller fragments, which helps explain the presence of large members within asteroid families. Thus, for the first time, numerical simulations successfully reproduced the sizes and ejection velocities of members of representative families. Moreover, the simulations provide constraints on the family dynamical histories and on the possible internal structure of family members and their parent bodies.

astro-ph.EP↗

arXiv2012

Numerical modeling of the disruption of Comet D/1993 F2 Shoemaker-Levy 9 representing the progenitor by a gravitationally bound assemblage of randomly shaped polyhedra

We advance the modeling of rubble-pile solid bodies by re-examining the tidal breakup of comet Shoemaker-Levy 9, an event that occurred during a 1.33 Jupiter radii encounter with that planet in July 1992. Tidal disruption of the comet nucleus led to a chain of sub-nuclei about 100-1000 m in diameter; these went on to collide with the planet two years later (Chodas & Yeomans 1996). They were intensively studied prior to and during the collisions, making SL9 the best natural benchmark for physical models of small body disruption. For the first time in the study of this event, we use numerical codes treating rubble-piles as collections of polyhedra (Korycansky & Asphaug 2009). This introduces forces of dilatation and friction, and inelastic response. As in our previous studies (Asphaug & Benz 1994,1996) we conclude that the progenitor must have been a rubble-pile, and we obtain approximately the same pre-breakup diameter (about 1.5 km) in our best fits to the data. We find that the inclusion of realistic fragment shapes leads to grain locking and dilatancy, so that even in the absence of friction or other dissipation we find that disruption is overall more difficult than in our spheres-based simulations. We constrain the comet's bulk density at about 300-400 kg/m^3, half that of our spheres-based predictions and consistent with recent estimates derived from spacecraft observations.

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