RICHARDSON , Derek C.

Numerical simulations of asteroid breakups, including both the fragmentation of the parent body and the gravitational interactions between the fragments, have allowed us to reproduce successfully the main properties of asteroid families formed in different regimes of impact energy, starting from a non-porous parent body. In this paper, using...

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The simple evidence that asteroid are composed by solid rocks suggests that their shape can be rather far from the theoretical equilibrium for rotating fluid bodies. The possible fragmented ("rubble-pile") nature of most of them has suggested interpretations based on elasto-plastic models (such as the Mohr-Coulomb theory) that take into account...

After the catastrophic disruption of a parent body, new objects are formed by the re-accumulation of the resulting fragments. A new dynamical family is thus formed. This phase is dominated by gravity, and the resulting bodies are cohesionless gravitational aggregates, also known as "rubble piles". Several lines of evidence suggest that a large...

Asteroid shapes and satellites: role of gravitational reaccumulation. Following current evidences, it is widely accepted that many asteroids would be "gravitational aggregates", i.e. bodies lacking internal cohesion. They could mainly be originated during the catastrophic disruption of some parent bodies, through the gravitational...

Several lines of evidences suggest that, after the breakup following a catastrophic disruption, the fragments can form asteroids that are kept together only by gravity. The details of the gravitational reaccumulation process are however poorly known. In particular, the angular momentum transported by the fragments could directly influence the...

Numerical N-body models adopting self-gravitating spherical particles have proven to have interesting properties and are very useful for describing some aspects of the expected behaviour of rubble-piles. In fact, particle interlocking can simulate a certain degree of shear strength (corresponding to a non-zero critical slope in the Mohr-Coulomb...

Since their formation, asteroids since their formation have experienced little physical, geological or thermal evolution. Like comets they are thought to be among the most pristine remnants of the early solar system. One physical process, however, has played a major role since the ancient times: collisions. Dynamical families were produced by...

Asteroids, since the formation of the solar system, are known to have experienced catastrophic collisions, which---depending on the impact energy---can produce a major disruption of the parent body and possibly give birth to asteroid families or binaries [1]. We present a general study of the final shape and dynamical state of asteroids...

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Non-gravitational effects (such as the "YORP" acceleration by thermal emission) may change their angular momentum of asteroids up to a few tens of km to the point to prevent any kind of rotational stability. Once instability is enforced mass loss may happen in more or less abrupt ways and potentially create satellites. We are studying this...

There have been attempts in the past to fit the observed bulk shapes (axial ratios) of asteroids to theoretical equilibrium figures for fluids, but these attempts have not been successful in many cases, evidently because asteroids are not fluid bodies. So far, however, the observed distribution of asteroid macroscopic shapes has never been...

Binary or multiple asteroids are important bodies that provide insight into the physical properties of asteroids in general. The knowledge of the components orbit in a binary provides the total mass with high accuracy and generally permits a rough bulk-density estimate [1,2]. We have observed 10 selected binary or multiple asteroids (22...