Abstract
Context.In the course of a close approach to planets or stars, the morphological and dynamical properties of rubble-pile small bodies can be dramatically modified, and some may catastrophically break up, as in the case of comet Shoemaker-Levy 9. This phenomenon is of particular interest for the understanding of the evolution and population of small bodies, and for making predictions regarding the outcomes of future encounters. Previous numerical explorations have typically used methods that do not adequately represent the nature of rubble piles. The encounter outcomes and influence factors are still poorly constrained.Aims.Based on recent advances in modeling rubble-pile physics, we aim to provide a better understanding of the tidal encounter processes of rubble piles through soft-sphere discrete element modeling (SSDEM) and to establish a database of encounter outcomes and their dependencies on encounter conditions and rubble-pile properties.Methods.We performed thousands of numerical simulations using the SSDEM implemented in theN-body codepkdgravto study the dynamical evolution of rubble piles during close encounters with the Earth. The effects of encounter conditions, material strength, arrangement, and resolution of constituent particles are explored.Results.Three typical tidal encounter outcomes are classified, namely: deformation, mass shedding, and disruption, ranging from mild modifications to severe damages of the progenitor. The outcome is highly dependent on the encounter conditions and on the structure and strength of the involved rubble pile. The encounter speed and distance required for causing disruption events are much smaller than those predicted by previous studies, indicating a smaller creation rate of tidally disrupted small body populations. Extremely elongated fragments with axis ratios ~1:6 can be formed by moderate tidal encounters. Our analyses of the spin-shape evolution of the largest remnants reveal reshaping mechanisms of rubble piles in response to tidal forces, which is consistent with stable rubble-pile configurations derived by continuum theory. A case study for Shoemaker-Levy 9 suggests a low bulk density (0.2–0.3 g cc−1) for its progenitor.
Highlights
The dynamical evolution of small bodies in planetary systems can sometimes lead to very close approaches to planets or stars that can either cause surface motion of the involved small body, modify its shape, or even catastrophically disrupt it
The most striking evidence of tidal disruption was provided by the encounter of comet Shoemaker-Levy 9 (SL9) with Jupiter that broke the body into 21 pieces when it approached within 1.33 Jovian radii of the planet center in 1992 (Sekanina et al 1994)
We perform a series of simulations using an hexagonal close packing (HCP) model with a lower number of particles to investigate the influence of the resolution on the outcomes. This low-resolution HCP model is almost identical to the rubble-pile model used in Schunová et al (2014), allowing us to make a one-to-one comparison of our soft-sphere discrete element method (SSDEM) and their hard-sphere discrete element method (HSDEM) results
Summary
The dynamical evolution of small bodies in planetary systems can sometimes lead to very close approaches to planets or stars that can either cause surface motion of the involved small body, modify its shape, or even catastrophically disrupt it. Tidal disruption events do occur in our Solar System, but they are common in exoplanetary systems and in different stages of star evolution (Jura 2003; Gillon et al 2014). The most striking evidence of tidal disruption was provided by the encounter of comet Shoemaker-Levy 9 (SL9) with Jupiter that broke the body into 21 pieces when it approached within 1.33 Jovian radii of the planet center in 1992 (Sekanina et al 1994). These pieces eventually collided with the giant planet during the subsequent encounter in July 1994
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
