Chaotic diffusion in the Solar System

Out of nine known stable Mars Trojans, seven appear to be members of an orbital grouping including the largest Trojan, Eureka. In order to test if this could be a genetic family, we simulated the long term evolution of a tight orbital cluster centered on Eureka. We explored two cases: cluster dispersal through planetary gravity alone over 1 Gyr, and a 1 Gyr evolution due to both gravity and the Yarkovsky effect. We find that the dispersal of the cluster in eccentricity is primarily due to dynamical chaos, while the inclinations and libration amplitudes are primarily changed by the Yarkovsky effect. Current distribution of the cluster members orbits are indicative of an initially tight orbital grouping that was affected by a negative acceleration (i.e. one against the orbital motion) consistent with the thermal Yarkovsky effect. We conclude that the cluster is a genetic family formed either in a collision or through multiple rotational fissions. The cluster's age is on the order of 1 Gyr, and its long-term orbital evolution is likely dominated by the seasonal, rather than diurnal, Yarkovsky effect. If confirmed, Gyr-scale dominance of the seasonal Yarkovsky effect may indicate suppression of the diurnal Yarkovsky drift by the related YORP effect. Further study of Mars Trojans is essential for understanding the long-term orbital and rotational dynamics of small bodies in the absence of frequent collisions.

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“…5). This is in agreement with previous work, for example the large sets of simulations done by Laskar (2008).…”

Section: Discussionsupporting

confidence: 94%

Yarkovsky-driven spreading of the Eureka family of Mars Trojans

Ćuk

Christou

Hamilton

2015

Icarus

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“…It is plausible that global chaos for these angles will either have a sufficiently long timescale or that the chaos will be "bounded" in a way that back integration will be effective. The main parameters that determine precession rates (masses, semimajor axes, eccentricities, and inclinations of the outer planets) are very stable (quasi-periodic) over the age of the solar system (Laskar 2008).…”

Section: Using Back Integrationmentioning

confidence: 99%

Identifying Collisional Families in the Kuiper Belt

Marcus

Ragozzine

Murray-Clay

et al. 2011

ApJ

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The identification and characterization of numerous collisional families-clusters of bodies with a common collisional origin-in the asteroid belt has added greatly to the understanding of asteroid belt formation and evolution. More recent study has also led to an appreciation of physical processes that had previously been neglected (e.g., the Yarkovsky effect). Collisions have certainly played an important role in the evolution of the Kuiper Belt as well, though only one collisional family has been identified in that region to date, around the dwarf planet Haumea. In this paper, we combine insights into collisional families from numerical simulations with the current observational constraints on the dynamical structure of the Kuiper Belt to investigate the ideal sizes and locations for identifying collisional families. We find that larger progenitors (r ∼ 500 km) result in more easily identifiable families, given the difficulty in identifying fragments of smaller progenitors in magnitude-limited surveys, despite their larger spread and less frequent occurrence. However, even these families do not stand out well from the background. Identifying families as statistical overdensities is much easier than characterizing families by distinguishing individual members from interlopers. Such identification seems promising, provided the background population is well known. In either case, families will also be much easier to study where the background population is small, i.e., at high inclinations. Overall, our results indicate that entirely different techniques for identifying families will be needed for the Kuiper Belt, and we provide some suggestions.

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“…The physics behind secular chaos is analyzed in detail in a companion paper (Lithwick & Wu 2011), where we show that Mercury, the innermost planet in our solar system, experiences a similar type of secular chaos. Mercury may consequently be removed from the solar system (Laskar 2008;Batygin & Laughlin 2008;Laskar & Gastineau 2009).…”

Section: Introductionmentioning

confidence: 99%

Secular Chaos and the Production of Hot Jupiters

Lithwick

2011

ApJ

378

356

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In a planetary system with two or more well-spaced, eccentric, inclined planets, secular interactions may lead to chaos. The innermost planet may gradually become very eccentric and/or inclined as a result of the secular degrees of freedom drifting toward equipartition of angular momentum deficit. Secular chaos is known to be responsible for the eventual destabilization of Mercury in our own solar system. Here we focus on systems with three giant planets. We characterize the secular chaos and demonstrate the criterion for it to occur, but leave a detailed understanding of secular chaos to a companion paper. After an extended period of eccentricity diffusion, the inner planet's pericenter can approach the star to within a few stellar radii. Strong tidal interactions and ensuing tidal dissipation extract orbital energy from the planet and pull it inward, creating a hot Jupiter. In contrast to other proposed channels for the production of hot Jupiters, such a scenario (which we term "secular migration") explains a range of observations: the pile-up of hot Jupiters at 3 day orbital periods, the fact that hot Jupiters are in general less massive than other radial velocity planets, that they may have misaligned inclinations with respect to stellar spin, and that they have few easily detectable companions (but may have giant companions in distant orbits). Secular migration can also explain close-in planets as low in mass as Neptune; and an aborted secular migration can explain the "warm Jupiters" at intermediate distances. In addition, the frequency of hot Jupiters formed via secular migration increases with stellar age. We further suggest that secular chaos may be responsible for the observed eccentricities of giant planets at larger distances and that these planets could exhibit significant spin-orbit misalignment.

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Chaotic diffusion in the Solar System

Cited by 142 publications

References 24 publications

Yarkovsky-driven spreading of the Eureka family of Mars Trojans

Yarkovsky-driven spreading of the Eureka family of Mars Trojans

Identifying Collisional Families in the Kuiper Belt

Secular Chaos and the Production of Hot Jupiters

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