The unexpected finding of a ring system around the Centaur (10199) Chariklo opened a new window for dynamical studies and posed many questions about the formation and evolutionary mechanisms of Centaurs as well as the relationship to satellites and outbursting activity. As minor planets that cross the orbits of the giant planets, Centaurs have short dynamical lifetimes: Centaurs are supplied from the trans-Neptunian region and some fraction migrates inward to become Jupiter-family comets. Given these dynamical pathways, a comparison of attributes across these classifications provides information to understand the source population(s) and the processes that have affected these minor planets throughout their lifetimes. In this chapter we review the current knowledge of satellites, rings, and debris around Centaur-like bodies, discuss the observational techniques involved, place the information into context with the trans-Neptunian Objects, and consider what the results tell us about the outer solar system. We also examine open questions and future prospects.

Dynamically studying trans-Neptunian object (TNO) binaries allows us to measure masses and orbits. Most of the known objects appear to have only two components, except (47171) Lempo, which is the single known hierarchical triple system with three similar-mass components. Though hundreds of TNOs have been imaged with high-resolution telescopes, no other hierarchical triples (or trinaries) have been found among solar system small bodies, even though they are predicted in planetesimal formation models such as gravitational collapse after the streaming instability. By going beyond the point-mass assumption and modeling TNO orbits as non-Keplerian, we open a new window into the shapes and spins of the components, including the possible presence of unresolved "inner" binaries. Here we present evidence for a new hierarchical triple, (148780) Altjira (2001 UQ18), based on non-Keplerian dynamical modeling of the two observed components. We incorporate two recent Hubble Space Telescope observations, leading to a 17 yr observational baseline. We present a new open-source Bayesian point-spread function fitting code called nPSF that provides precise relative astrometry and uncertainties for single images. Our non-Keplerian analysis measures a statistically significant (∼2.5σ) nonspherical shape for Altjira. The measured J2 is best explained as an unresolved inner binary, and an example hierarchical triple model gives the best fit to the observed astrometry. Using an updated non-Keplerian ephemeris (which is significantly different from the Keplerian predictions), we show that the predicted mutual event season for Altjira has already begun, with several excellent opportunities for observations through ∼2030.

The physical and orbital parameters of trans-Neptunian objects provide valuable information about the solar system's formation and evolution. In particular, the characterization of binaries provides insights into the formation mechanisms that may be playing a role at such large distances from the Sun. Studies show two distinct populations, and (38628) Huya occupies an intermediate position between the unequal-sized binaries and those with components of roughly equal sizes. In this work, we predicted and observed three stellar occultation events by Huya. Huya and its satellitewere detected during occultations in 2021 March and again in 2023 June. Additionally, an attempt to detect Huya in 2023 February resulted in an additional single-chord detection of the secondary. A spherical body with a minimum diameter of D = 165 km can explain the three single-chord observations and provide a lower limit for the satellite size. The astrometry of Huya's system, as derived from the occultations and supplemented by observations from the Hubble Space Telescope and Keck Observatory, provided constraints on the satellite orbit and the mass of the system. Therefore, assuming the secondary is in an equatorial orbit around the primary, the limb fitting was constrained by the satellite orbit position angle. The system density, calculated by summing the most precise measurement of Huya's volume to the spherical satellite average volume, is ρ1 = 1073 ± 66 kg m−3. The density that the object would have assuming a Maclaurin equilibrium shape with a rotational period of 6.725 ± 0.01 hr is ρ2 = 768 ± 42 kg m−3. This difference rules out the Maclaurin equilibrium assumption for the main body shape.

The Haumea family is the only known dynamical family in the trans-Neptunian region. To date, 10 family members have been unambiguously identified using near-infrared (NIR) spectral or photometric data in combination with their strong dynamical proximity and the rest of the family. In this work, we build off previous empirically constructed models of the family to identify 39 candidate family members and follow up on eight of them using the Hubble Space Telescope (HST) to measure their visible and NIR colors. Six of the candidates have strong water-ice absorption features—consistent with family membership. Based on these initial findings, our sample of 39 candidate family members should contain about 20 more water-rich objects. Combining the HST visible and NIR photometry with past results, we find no evidence for significant color heterogeneity within the family. Of the six new family members, two have Δv ∼ 300 m s−1, well outside of the traditionally defined velocity dispersion limit of ∼150 m s−1. As evidence suggests they are not affected by any of Neptune's resonances, we propose that these family members are the result of dynamical sculpting by Neptune during its outward migration. Further searches for far-flung family members will be able to further explore this hypothesis.

We present a new catalog of Kepler planet candidates that prioritizes accuracy of planetary dispositions and properties over uniformity. This catalog contains 4376 transiting planet candidates, including 1791 residing within 709 multiplanet systems, and provides the best parameters available for a large sample of Kepler planet candidates. We also provide a second set of stellar and planetary properties for transiting candidates that are uniformly derived for use in occurrence rate studies. Estimates of orbital periods have been improved, but as in previous catalogs, our tabulated values for period uncertainties do not fully account for transit timing variations (TTVs). We show that many planets are likely to have TTVs with long periodicities caused by various processes, including orbital precession, and that such TTVs imply that ephemerides of Kepler planets are not as accurate on multidecadal timescales as predicted by the small formal errors (typically 1 part in 10(6) and rarely >10(-5)) in the planets' measured mean orbital periods during the Kepler epoch. Analysis of normalized transit durations implies that eccentricities of planets are anticorrelated with the number of companion transiting planets. Our primary catalog lists all known Kepler planet candidates that orbit and transit only one star; for completeness, we also provide an abbreviated listing of the properties of the two dozen nontransiting planets that have been identified around stars that host transiting planets discovered by Kepler.

The dwarf planet Haumea is one of the most compelling trans-Neptunian objects to study, hosting two small, dynamically interacting satellites, a family of nearby spectrally unique objects, and a ring system. Haumea itself is extremely oblate due to its 3.9 hr rotation period. Understanding the orbits of Haumea's satellites, named Hi'iaka and Namaka, requires detailed modeling of both satellite–satellite gravitational interactions and satellite interactions with Haumea's nonspherical gravitational field (parameterized here as J2). Understanding both of these effects allows for a detailed probe of the satellites' masses and Haumea's J2 and spin pole. Measuring Haumea's J2 provides information about Haumea's interior, possibly determining the extent of past differentation. In an effort to understand the Haumea system, we have performed detailed non-Keplerian orbit fitting of Haumea's satellites using a decade of new, ultra-precise observations. Our fits detect Haumea's J2 and spin pole at ≳2.5σ confidence. Degeneracies present in the dynamics prevent us from precisely measuring Haumea's J2 with the current data, but future observations should enable a precise measurement. Our dynamically determined spin pole shows excellent agreement with past results, illustrating the strength of non-Keplerian orbit fitting. We also explore the spin–orbit dynamics of Haumea and its satellites, showing that axial precession of Hi'iaka may be detectable over decadal timescales. Finally, we present an ephemeris of the Haumea system over the coming decade, enabling high-quality observations of Haumea and its satellites for years to come.