Plusieurs indices suggèrent qu'un grand nombre d'astéroïdes seraient des empilements de gravats, liés uniquement par gravité et quasiment dépourvus de cohésion interne. Leur formation serait due à la réaccumulation de fragments issus de la destruction antérieure d'un corps parent. La forme de ces objets, que l'on observe, pourrait ainsi être liée à ce processus de réaccumulation gravitationnelle. Toutefois, à l'heure actuelle, on ignore si les formes observées des astéroïdes sont le résultat de la seule réaccumulation ou d'événements ultérieurs entrainant un réajustement de la forme du corps.
Dans cette Note, nous nous interrogeons sur l'origine des formes des astéroïdes. A l'aide d'une étude numérique de la réaccumulation, nous étudions les formes d'équilibres possibles correspondants aux modèles théoriques. Les résultats montrent, pour la première fois, que seulement une catégorie précise de formes (sphéroïdes aplatis) est apparemment crée via ce mécanisme. Ces résultats pourraient ainsi fournir d'interessantes contraintes sur l'évolution des formes d'astéroïdes, notamment pour ceux possédant un, ou plusieurs, satellites.
Following current evidence, it is widely accepted that many asteroids would be ‘gravitational aggregates’, i.e. bodies lacking internal cohesion. They could mainly originate from the catastrophic disruption of some parent body, through the gravitational re-accumulation of the resulting fragments. The same events produced the dynamical families that we observe. In this work we address the problem of the origin of shapes of gravitational aggregates, that could contain signatures of their origin. We use a N-body code to simulate the collapse of a cloud of fragments, with a variety of initial velocity distributions and total angular momentum. The fragments are treated as inelastic spheres, that rapidly accumulate to form rotating aggregates. The resulting shapes and rotational properties are compared with theoretical predictions. The results show that only a precise category of shapes (flattened spheroids) are created via this mechanism. This may provide interesting constraints on the evolution of asteroid shapes, in particular for those with one or more satellites.
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Keywords: Solar System, Asteroids, Satellites, Collisions
Jean-François Consigli 1, 2 ; Paolo Tanga 2 ; Carlo Comito 2, 3 ; Daniel Hestroffer 4 ; Derek C. Richardson 5
@article{CRPHYS_2007__8_3-4_469_0,
author = {Jean-Fran\c{c}ois Consigli and Paolo Tanga and Carlo Comito and Daniel Hestroffer and Derek C. Richardson},
title = {Formes d'ast\'ero{\"\i}des et formation de satellites : r\^ole de la r\'eaccumulation gravitationnelle},
journal = {Comptes Rendus. Physique},
pages = {469--480},
publisher = {Elsevier},
volume = {8},
number = {3-4},
year = {2007},
doi = {10.1016/j.crhy.2007.02.006},
language = {fr},
}
TY - JOUR AU - Jean-François Consigli AU - Paolo Tanga AU - Carlo Comito AU - Daniel Hestroffer AU - Derek C. Richardson TI - Formes d'astéroïdes et formation de satellites : rôle de la réaccumulation gravitationnelle JO - Comptes Rendus. Physique PY - 2007 SP - 469 EP - 480 VL - 8 IS - 3-4 PB - Elsevier DO - 10.1016/j.crhy.2007.02.006 LA - fr ID - CRPHYS_2007__8_3-4_469_0 ER -
%0 Journal Article %A Jean-François Consigli %A Paolo Tanga %A Carlo Comito %A Daniel Hestroffer %A Derek C. Richardson %T Formes d'astéroïdes et formation de satellites : rôle de la réaccumulation gravitationnelle %J Comptes Rendus. Physique %D 2007 %P 469-480 %V 8 %N 3-4 %I Elsevier %R 10.1016/j.crhy.2007.02.006 %G fr %F CRPHYS_2007__8_3-4_469_0
Jean-François Consigli; Paolo Tanga; Carlo Comito; Daniel Hestroffer; Derek C. Richardson. Formes d'astéroïdes et formation de satellites : rôle de la réaccumulation gravitationnelle. Comptes Rendus. Physique, Volume 8 (2007) no. 3-4, pp. 469-480. doi : 10.1016/j.crhy.2007.02.006. https://comptes-rendus.academie-sciences.fr/physique/articles/10.1016/j.crhy.2007.02.006/
[1] Collisional evolution of asteroids: populations, rotations and velocities, Asteroids, University of Arizona Press, 1979, pp. 528-557
[2] The asteroids as outcomes of catastrophic collisions, Icarus, Volume 52 (1982), pp. 409-433
[3] Formation of asteroid families by catastrophic disruption: simulations with fragmentation and gravitational reaccumulation, Icarus, Volume 160 (2002), pp. 10-23 (Voir aussi: Collisions and gravitational reaccumulation: forming asteroid families and satellites Science, 294, 2001, pp. 1696-1700)
[4] The formation of asteroidal satellites in catastrophic collisions, Icarus, Volume 120 (1996), pp. 212-219
[5] The formation of asteroid satellites in large impacts: results from numerical simulations, Icarus, Volume 167 (2004), pp. 382-396
[6] The formation of binary asteroids as outcomes of catastrophic collisions, Planetary Space Science, Volume 45 (1997), pp. 757-770
[7] The lifetime of binary asteroids vs. gravitational encounters and collisions, Icarus, Volume 94 (1991), pp. 299-310
[8] Stability of binary asteroids, Icarus, Volume 159 (2002), pp. 271-283
[9] Fast and slow rotation of asteroids, Icarus, Volume 148 (2000), pp. 12-20
[10] A.W. Harris, The rotation rates of very small asteroids: evidence for rubble-pile structure, in: Lunar and Planetary Science Conference, vol. 27, 1996, pp. 493–494
[11] NEAR's Flyby of 253 Mathilde: images of a C-asteroid, Science, Volume 279 (1997), pp. 2109-2114
[12] Estimating the mass of asteroid 253 Mathilde from tracking data during the NEAR flyby, Science, Volume 279 (1997), pp. 2106-2109
[13] Target porosity effects on impact cratering, and collisional disruption, Icarus, Volume 105 (1993), pp. 216-224
[14] Compaction as the origin of the unusual craters on the asteroid Mathilde, Nature, Volume 402 (1999), pp. 155-157
[15] Numerical experiments with rubble piles: equilibrium shapes and spins, Icarus, Volume 173 (2005), pp. 349-361
[16] Determination of pole orientations and shapes of asteroids, Asteroids II, University of Arizona Press, 1989, pp. 67-97
[17] Models of twenty asteroids from photometric data, Icarus, Volume 159 (2002), pp. 369-395
[18] Triaxial equilibrium ellipsoids among the asteroids, Icarus, Volume 46 (1981), pp. 114-123
[19] Asteroids observations with the Hubble Space Telescope FGS: observing strategy, data analysis and modelling process, Astronomy & Astrophysics, Volume 391 (2002), pp. 1123-1132
[20] Asteroids observations with the Hubble Space Telescope FGS: duplicity search and size measurements for 6 asteroids, Astronomy & Astrophysics, Volume 401 (2003), pp. 733-741
[21] How fast can an asteroid spin?, Icarus, Volume 46 (1981), pp. 124-126
[22] Photometric geodesy of main-belt asteroids: II. Analysis of lightcurves for poles, periods, and shapes, Icarus, Volume 76 (1988), pp. 19-77
[23] D. Hestroffer, P. Tanga, Figures of equilibrium among binary asteroids, in: AAS, DPS meeting 37, 15.30, 2005
[24] Fission sequence and equilibrium models of rigidity rotating polytropes, Astrophysics and Space Science, Volume 99 (1984), pp. 71-74
[25] Ellipsoidal figures of equilibrium—compressible models, Astrophysical Journal Supplement, Volume 88 (1993), pp. 205-252
[26] Equilibrium configurations of solid cohesionless bodies, Icarus, Volume 154 (2001), pp. 432-448
[27] Ellipsoidal Figures of Equilibrium, Yale University Press, 1969
[28] A hierarchical force-calculation algorithm, Nature, Volume 324 (1986), pp. 446-449
[29] Linking the collisional history of the main asteroid belt to its dynamical excitation and depletion, Icarus, Volume 179 (2005), pp. 63-94
[30] Asteroids from observations to models, Lect. Notes Phys. Series, vol. 682, 2006, pp. 89-116
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