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Jacobson S.A.,Laboratoire Lagrange | Jacobson S.A.,University of Bayreuth
Proceedings of the International Astronomical Union | Year: 2016

Rotationally fissioned asteroids produce unbound asteroid pairs that have very similar heliocentric orbits. Backward integration of their current heliocentric orbits provides an age of closest proximity that can be used to date the rotational fission event. Most asteroid pairs follow a predicted theoretical relationship between the primary spin period and the mass ratio of the two pair members that is a direct consequence of the YORP-induced rotational fission hypothesis. If the progenitor asteroid has strength, asteroid pairs may have higher mass ratios or faster rotating primaries. However, the process of secondary fission leaves the originally predicted trend unaltered. We also describe the characteristics of pair members produced by four alternative routes from a rotational fission event to an asteroid pair. Unlike direct formation from the event itself, the age of closest proximity of these pairs cannot generally be used to date the rotational fission event since considerable time may have passed. Copyright © 2016 International Astronomical Union.

Krstulovic G.,Laboratoire Lagrange
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2012

We study the statistical properties of the Kelvin waves propagating along quantized superfluid vortices driven by the Gross-Pitaevskii equation. No artificial forcing or dissipation is added. Vortex positions are accurately tracked. This procedure directly allows us to obtain the Kevin-wave occupation-number spectrum. Numerical data obtained from long time integration and ensemble average over initial conditions support the spectrum proposed in L'vov and Nazarenko. Kelvin-wave modes in the inertial range are found to be Gaussian as expected by weak-turbulence predictions. Finally the dissipative range of the Kelvin-wave spectrum is studied. Strong non-Gaussian fluctuations are observed in this range. © 2012 American Physical Society.

Jacobson S.A.,Laboratoire Lagrange | Jacobson S.A.,University of Bayreuth
Proceedings of the International Astronomical Union | Year: 2014

Recently, the discovery of small unbound asteroid systems called asteroid pairs have revolutionized the study of small asteroid systems. Observations with radar, photometric and direct imaging techniques have discovered that multiple asteroid systems can be divided clearly into a handful of different morphologies. Simultaneously, new theoretical advances have demonstrated that solar radiation dictates the evolution of small asteroids with strong implications for asteroid internal structure. We review our current understanding of how small asteroid systems evolve and point to the future. © Copyright 2014 International Astronomical Union.

Fraser W.C.,Herzberg Institute for Astrophysics | Fraser W.C.,California Institute of Technology | Brown M.E.,California Institute of Technology | Morbidelli A.,Laboratoire Lagrange | And 2 more authors.
Astrophysical Journal | Year: 2014

Here we measure the absolute magnitude distributions (H-distribution) of the dynamically excited and quiescent (hot and cold) Kuiper Belt objects (KBOs), and test if they share the same H-distribution as the Jupiter Trojans. From a compilation of all useable ecliptic surveys, we find that the KBO H-distributions are well described by broken power laws. The cold population has a bright-end slope, , and break magnitude, (r′-band). The hot population has a shallower bright-end slope of, , and break magnitude . Both populations share similar faint-end slopes of α2 0.2. We estimate the masses of the hot and cold populations are 0.01 and 3 × 10-4 M ⊕. The broken power-law fit to the Trojan H-distribution has α1 = 1.0 ± 0.2, α2 = 0.36 ± 0.01, and H B = 8.3. The Kolmogorov-Smirnov test reveals that the probability that the Trojans and cold KBOs share the same parent H-distribution is less than 1 in 1000. When the bimodal albedo distribution of the hot objects is accounted for, there is no evidence that the H-distributions of the Trojans and hot KBOs differ. Our findings are in agreement with the predictions of the Nice model in terms of both mass and H-distribution of the hot and Trojan populations. Wide-field survey data suggest that the brightest few hot objects, with , do not fall on the steep power-law slope of fainter hot objects. Under the standard hierarchical model of planetesimal formation, it is difficult to account for the similar break diameters of the hot and cold populations given the low mass of the cold belt. © 2014. The American Astronomical Society. All rights reserved.

Jacobson S.A.,University of Colorado at Boulder | Jacobson S.A.,Laboratoire Lagrange | Jacobson S.A.,University of Bayreuth | Scheeres D.J.,University of Colorado at Boulder | McMahon J.,University of Colorado at Boulder
Astrophysical Journal | Year: 2014

We propose and analyze a new mechanism for the formation of the wide asynchronous binary population. These binary asteroids have wide semimajor axes relative to most near-Earth and main belt asteroid systems. Confirmed members have rapidly rotating primaries and satellites that are not tidally locked. Previously suggested formation mechanisms from impact ejecta, from planetary flybys, and directly from rotational fission events cannot satisfy all of the observations. The newly hypothesized mechanism works as follows: (1) these systems are formed from rotational fission, (2) their satellites are tidally locked, (3) their orbits are expanded by the binary Yarkovsky-O'Keefe- Radzievskii-Paddack (BYORP) effect, (4) their satellites desynchronize as a result of the adiabatic invariance between the libration of the secondary and the mutual orbit, and (5) the secondary avoids resynchronization because of the YORP effect. This seemingly complex chain of events is a natural pathway for binaries with satellites that have particular shapes, which define the BYORP effect torque that acts on the system. After detailing the theory, we analyze each of the wide asynchronous binary members and candidates to assess their most likely formation mechanism. Finally, we suggest possible future observations to check and constrain our hypothesis. © 2014. The American Astronomical Society. All rights reserved..

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