Astronomy
Ivana Milić Žitnik
7 papers · 3 Must Read · 1998–2026
Last updated Mar 17, 2026
Sorted by publication date, newest first. New papers are marked so you can spot recent additions.
Guido, Alessia Francesca, Efthymiopoulos, Christos · 2026
This study explores the heteroclinic connections linking the stable and unstable manifolds of periodic orbits within the framework of the Sun-Jupiter planar restricted three-body problem.
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Paweł Wajer, Małgorzata Królikowska, Jakub Suchecki · 2026 · Monthly Notices of the Royal Astronomical Society
Clone-ensemble Lyapunov times are more robust than nominal-orbit values and reduce method bias for TNOs and outer MBAs.
This paper benchmarks three common numerical ways to compute Lyapunov times—variational equations and two renormalized “nearby trajectory” schemes—on both trans-Neptunian objects and outer main-belt asteroids. By repeating the calculation over 1001 orbital clones per object, it shows that ensemble statistics (especially medians) are often more reliable stability indicators than a single best-fit orbit, revealing multimodal or mixed stability that nominal-orbit estimates can miss (notably for 2010 HE79 and 2010 EL139). The study also finds method-to-method agreement is typically better for the (hot) TNO sample than for outer-belt asteroids, consistent with the main belt’s denser network of overlapping resonances, and it highlights cases where simplified dynamical models can strongly distort Lyapunov-time inference. Overall, it provides a practical framework for scaling Lyapunov-time stability classification to larger small-body populations while explicitly accounting for orbit uncertainty and numerical-method sensitivity.
They computed Lyapunov times for a sample of trans-Neptunian objects and outer main-belt asteroids using three numerical approaches: the variational method and two implementations of the renormalization technique.
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Zoran Knežević · 2025 · Celestial Mechanics and Dynamical Astronomy
The purpose of this paper is to draw attention to failures in computation of asteroid synthetic proper elements with a goal to point out the dynamical or computational causes of the failures.
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I. Wlodarczyk · 2024 · Astronomy & Astrophysics
Adds Yarkovsky/YORP to 10 Myr clone integrations of retrograde asteroids, quantifying chaos, spin evolution, and drift rates.
This paper compiles orbital and physical parameters for all numbered retrograde asteroids (plus selected unnumbered ones) and follows their evolution with ensembles of orbital clones. By explicitly including Yarkovsky and YORP nongravitational forces, it shows these rare retrograde objects have strongly chaotic dynamics (short Lyapunov times) and that adding thermal forces typically shortens Lyapunov times relative to gravity-only models. Over 10 Myr, the simulations predict modest average spin-up (rotation periods decrease by ~8%) with a non-negligible minority spinning down, and a drift-rate (da/dt) distribution concentrated near zero but with an asymmetry toward positive drift. The results argue that long-term modeling of retrograde asteroids should not ignore nongravitational effects, even when they are hard to measure directly.
It is studied the dynamical orbital and physical evolution of all 21 numbered and 13 selected unnumbered asteroids in retrograde orbits. They computed their starting orbital elements, absolute magnitudes, and diameters, together with the non-gravitational parameters A2 and da/dt.
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O. C. Winter, D. C. Mourão, S. M. Giuliatti Winter · 2010 · Astronomy & Astrophysics
A simple “radial Lyapunov” diagnostic separates short-time chaos that escapes from chaos that stays radially confined.
Short Lyapunov times usually signal rapid orbital diffusion, but some bodies remain radially bounded despite being strongly chaotic (“confined/stable chaos”). This paper introduces an easy add-on to standard Lyapunov exponent calculations that estimates how much of the divergence occurs specifically in the radial direction by measuring separations in a rotating frame aligned with the orbit’s radius. Applied to asteroids perturbed by Jupiter and to Saturn F-ring moonlets perturbed by Prometheus/Pandora, the method cleanly distinguishes escapers (radial contribution comparable to total) from confined chaos (radial contribution orders of magnitude smaller). The implication is a practical screening tool: short Lyapunov time alone is insufficient, but “radial LCE” helps predict whether chaos will translate into large semimajor-axis/radius changes.
It is presented a simple approach to estimating the contribution of the radial component of the LCE to identify trajectories in the “confined chaos” regime.
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Zoran Kneževic, Slobodan Ninkovic · 2004 · Proceedings of the International Astronomical Union
Tests show maximum Lyapunov exponents from finite asteroid integrations are usually reliable, but can fail when dynamics shift.
This paper asks whether catalogued maximum Lyapunov characteristic exponents (LCEs) for asteroids—computed from finite-time numerical integrations—can be trusted as indicators of chaos. Using large-scale Orbit9/OrbFit integrations, the authors compare LCE estimates from forward vs. backward propagation and from different integration lengths (2, 10, 100 Myr), finding agreement for most objects (≈81.5% in ±1 Myr tests; ≈63.5% in a problem-biased 2 vs. 10 Myr subset). The main failure mode is not numerical noise per se but real time-variability: some asteroids switch dynamical regimes, producing slope changes in γ(t) and integration-span–dependent LCE estimates. Practically, the results support using catalog LCEs for broad classification (regular vs. chaotic; weak/moderate vs. strong chaos) while flagging a minority where LCEs are intrinsically unstable over time.
It is presented an analysis of the reliability of computation of maximum Characteristic Exponents of Lyapunov from the numerical integrations of asteroid orbits over finite intervals of time.
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N. Murray, M. Holman, M. Potter · 1998 · The Astronomical Journal
Saturn’s forcing of Jupiter creates chaotic three-body “sideband” resonances that dominate the chaos across much of the asteroid belt.
This paper explains why asteroid orbits can be chaotic even where classic Jupiter–asteroid mean-motion resonances are absent. Murray, Holman, and Potter show that Saturn-driven variations in Jupiter’s orbit generate nearby three-body “sideband” (Laplace-type) resonances whose subresonances overlap, producing new chaotic zones adjacent to standard two-body resonances. They derive simple scaling formulas for sideband widths, Lyapunov times, and eccentricity-diffusion (removal) times, and verify them with targeted numerical integrations. The results imply that many outer-belt asteroids reside in these three-body resonances, with some experiencing eccentricity growth leading to ejection on timescales shorter than the Solar System’s age.
It is showed that many three-body resonances involving the longitude of Saturn are chaotic. They gave simple expressions for the width of the chaotic region and the associated Lyapunov time.
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