A number of intriguing patterns have been identified in the distributions of the orbital elements of the known extreme trans-Neptunian objects or ETNOs --those with semimajor axis greater than 150 au and perihelion distance greater than 30 au. The announcement of the discovery of 2015 BP519, also known as Caju, has been hailed by some as a consistent piece of robust evidence for the existence of a yet-to-be-discovered massive planet far beyond the trans-Neptunian belt. In this Note, we use the latest data available to provide evidence against 2015 BP519 having followed the same dynamical pathway that placed other ETNOs where they are now. As an statistical outlier within the 29 known ETNOs, 2015 BP519 cannot be used as a reference to further support the trends perhaps present for other ETNOs. Asteroid 2015 BP519 represents a case of extreme dynamical anticorrelation within the ETNO orbital realm and the value of the distance to its descending node, nearly 700 au from the Sun, is the largest of any known ETNO.
This article reviews the different mechanisms affecting the orbits of trans-Neptunian objects, ranging from internal perturbations (planetary scattering, mean-motion resonances, secular effects) to external perturbations (galactic tides, passing stars). We outline the theoretical tools that can be used to model and study them, focussing on analytical approaches. We eventually compare these mechanisms to the observed distinct populations of trans-Neptunian objects and conclude on how they participate to the sculpting of the whole distribution.
Context: The discovery of distant trans-Neptunian objects has led to heated discussions about the structure of the outer Solar System. Aims: We study the dynamical evolution of small bodies from the Hill regions of migrating giant gaseous clumps that form in the outer solar nebula via gravitational fragmentation. We attempt to determine whether the observed features of the orbital distribution of distant trans-Neptunian objects could be caused by this process. Methods: We consider a simple model that includes the Sun, two point-like giant clumps with masses of ~ 10 Jupiter masses, and a set of…
The Pluto system is an archetype for the multitude of icy dwarf planets and accompanying satellite systems that populate the vast volume of the solar system beyond Neptune. New Horizons' exploration of Pluto and its five moons gave us a glimpse into the range of properties that their kin may host. Furthermore, the surfaces of Pluto and Charon record eons of bombardment by small trans-Neptunian objects, and by treating them as witness plates we can infer a few key properties of the trans-Neptunian population at sizes far below current direct-detection limits. This chapter summarizes what we hav…
Trans-Neptunian objects and Centaurs are small solar system bodies that reside in the outer parts of the solar system. These objects present photometric behaviours that are influenced due to a change in their aspect angle. Using absolute photometric measurements and rotational light-curves at different location on their orbits allow to model their photometric behaviour and obtain physical properties such as pole orientation, shape, density, and even detecting different peculiarities as departure from hydrostatic equilibrium or rings. In this work, I present how these models are performed in or…
The dependences of inclinations of orbits of secondaries in the discovered trans-Neptunian binaries on the distance between the primary and the secondary, on the eccentricity of orbits of the secondary around the primary, on the ratio of diameters of the secondary and the primary, and on the elements of heliocentric orbits of these binaries are studied. These dependences are interpreted using the model of formation of a satellite system in a collision of two rarefied condensations composed of dust and/or objects less than 1 m in diameter. It is assumed in this model that a satellite system for…
The formation of trans-Neptunian satellite systems at the stage of rarefied preplanetesimals (i.e., condensations of dust and/or objects less than 1 m in diameter) is discussed. It is assumed that trans-Neptunian objects (including those with satellites) could form as a result of compression of parental rarefied preplanetesimals. The formulas for calculating the angular momentum of two colliding condensations with respect to their center of mass, which were applied earlier in (Ipatov, 2010) in the comparison of such momenta with the angular momenta of observed satellite systems, are used to es…
Neptunian Trojans (NTs), trans-Neptunian objects in 1:1 mean-motion resonance with Neptune, are generally thought to have been captured from the original trans-Neptunian protoplanetary disk into co-orbital resonance with the ice giant during its outward migration. It is possible, therefore, that the colour distribution of NTs is a constraint on the location of any colour transition zones that may have been present in the disk. In support of this possible test, we obtained $g$, $r$, and $i$-band observations of 18 NTs, more than doubling the sample of NTs with known visible colours to 31 object…
Aims. We study the dynamical evolution of a system consisting of the giant planets and a massive planetesimal disk over the age of the Solar System. The main question addressed in this study is whether distant trans-Neptunian objects could have come about as a result of the combined action of planetary perturbations and the self-gravity of the disk. Methods. We carried out a series of full N-body numerical simulations of gravitational interactions between the giant planets and a massive outer disk of planetesimals. Results. Our simulations show that the collective gravity of the giant planets …
A relatively massive and moderately eccentric disk of trans-Neptunian objects (TNOs) can effectively counteract apse precession induced by the outer planets, and in the process shepherd highly eccentric members of its population into nearly-stationary configurations which are anti-aligned with the disk itself. We were sufficiently intrigued by this remarkable feature to embark on an extensive exploration of the full spatial dynamics sustained by the combined action of giant planets and a massive trans-Neptunian debris disk. In the process, we identified ranges of disk mass, eccentricity and pr…
In this work, we focused on observations of six trans-Neptunian objects (TNOs) whose apparent magnitudes are brighter than 20 mag. We present the results of astrometric and photometric observations of (134340) Pluto, (136108) Haumea, (136472) Makemake, (136199) Eris, (90482) Orcus and (20000) Varuna obtained at the Kyiv comet station (Code MPC 585) in 2017-2019. For observations, we used the 0.7-m reflector AZT-8 with the FLI PL4710 CCD camera and filters of the Johnson-Cousins photometric system. From our images, we measured the objects astrometric positions, calculated apparent magnitudes in…
The discovery and characteristics of transneptunian binaries are reviewed. In the 20 years since their first discovery, a wealth of detail has emerged including the frequency of binaries in different populations, their relative sizes and separations, and colors. Taken globally, these properties give strong clues to the origin and evolution of the populations where these binaries are found. In the last ten years and increasing number of binary orbits have been determined which yields a new trove of information on their masses and densities as well as details of their orbits including inclinatio…
Dynamical features of a massive disk of distant trans-Neptunian objects are considered in the model of the formation of small bodies in the Hill region of a giant gas-dust clump that arose as a result of gravitational instability and fragmentation of the protoplanetary disk. The dynamical evolution of orbits of small bodies under the action of gravitational perturbations from the outer planets and self-gravity of the disk has been studied for a time interval of the order of a billion years. It is shown that the secular effects of the gravitational action of a massive disk of small bodies lead …
Secular dynamics inside MMRs plays an essential role in governing the dynamical structure of the trans-Neptunian region and sculpting the orbital distribution of trans-Neptunian objects (TNOs). In this study, semi-analytical developments are made to explore the von Zeipel-Lidov-Kozai (ZLK) resonance inside mean motion resonances (MMRs). To this end, a semi-secular model is formulated by averaging theory and then a single-degree-of-freedom integrable model is achieved based on the adiabatic invariance approximation. In particular, we introduce a modified adiabatic invariant, which is continuous…
Space-based observatories at the second Sun-Earth Lagrange Point (L2) offer a unique opportunity to efficiently determine the orbits of distant solar system objects by taking advantage of the parallax effect that arises from nearly simultaneous ground- and space-based observations. Given the typical orbit of an observatory about L2, the observational baseline of $\sim1.5\times10^6$ km between L2 and Earth results in an instantaneous parallax of $\sim$10''-100'', even for the most distant of detectable trans-Neptunian objects (TNOs) in our solar system. Current ground-based strategies for measu…
Asymmetric debris discs have been found around stars other than the Sun; asymmetries are sometimes attributed to perturbations induced by unseen planets. The presence or absence of asymmetries in our own trans-Neptunian belt remains controversial. The study of sensitive tracers in a sample of objects relatively free from the perturbations exerted by the four known giant planets and most stellar flybys may put an end to this debate. The analysis of the distribution of the mutual nodal distances of the known extreme trans-Neptunian objects (ETNOs) that measure how close two orbits may get to eac…
Numerical analysis of Lyapunov Times for Trans-Neptunian Objects and Main-Belt Asteroids: stability, accuracy, and methodological comparisons
Centrum Badań Kosmicznych Polskiej Akademii Nauk (CBK PAN)（波兰科学院太空研究中心）；Astronomical Observatory, University of Warsaw（华沙大学天文台）；Cilium Engineering Sp. z o.o.（Cilium工程公司）
Photometric Measurements of H2O Ice Crystallinity on Trans-Neptunian Objects
我们提出了一种测量水冰结晶度的表面上的trans-neptunian对象（TNOs）的近红外窄带成像。新开发的光度技术使我们能够有效地确定在结晶H2O冰的1.65微米的吸收功能的强度。我们的数据为三个大的对象，妊神星，夸欧尔星和奥库斯，这是已知的表面上含有结晶水冰，显示了合理的结果与高分数的结晶相。当H_2O-冰颗粒尺寸大于~20 μ m时，堆积度明显低于1.0，表明存在非晶相。特别是，奥库斯表现出高丰度的无定形H2O冰相比，妊神星和夸欧尔星，可能表明体的体积密度和表面结晶度之间的相关性。我们还发现了结晶H2O冰的存在Typhon和2008 AP 129，这两个都小于最小尺寸限制诱导cryovolcanism以及从无定形过渡到结晶通过热演化由于长寿命同位素的衰变。
We report the rotational lightcurves of 21 trans-Neptunian objects (TNOs) in Neptune's 2:1 mean motion resonance obtained with the 6.5 m Magellan-Baade telescope and the 4.3 m Lowell Discovery Telescope. The main survey's goal is to find objects displaying a large lightcurve amplitude which is indicative of contact binaries or highly elongated objects. In our sample, two 2:1 resonant TNOs showed a significant short-term lightcurve amplitude: 2002 VD$_{130}$ and (531074) 2012 DX$_{98}$. The full lightcurve of 2012 DX$_{98}$ infers a periodicity of 20.80$\pm$0.06h and amplitude of 0.56$\pm$0.03m…
We carried out an extensive analysis of the stability of the outer solar system, making use of the frequency analysis technique over short-term integrations of nearly a hundred thousand test particles, as well as a statistical analysis of 200, 1 Gyr long numerical simulations, which consider the mutual perturbations of the giant planets and the 34 largest trans-Neptunian objects (we have called all 34 objects ``dwarf planets'', DPs, even if probably only the largest of them are true DPs). From the frequency analysis we produced statistical diffusion maps for a wide region of the $a$-$e$ phase-…
Discovery of a satellite of the large trans-Neptunian object (225088) 2007OR10
2007 OR 10是目前已知的第三大矮行星，有效辐射直径约为1535公里。它有一个缓慢的旋转周期约45小时，被怀疑是由当时未被发现的卫星的潮汐相互作用引起的。在这里，我们报告发现一个可能的卫星2007 OR 10，确定档案哈勃太空望远镜WFC 3/UVIS系统图像。虽然卫星是在两个历元上被探测到的，但这并不能明确地确定轨道和轨道周期。对系统质量的可行估计为1.5-5.8x10^21 kg，因此轨道周期可能为35 - 100 d。在哈勃望远镜的图像中，这颗卫星比2007 OR 10暗4.2米，相当于237公里的直径，假设它与主星有相等的椭圆度。由于月球的体积相对较小，因此先前对月球的大小和轨道的估计保持不变。有了这个发现，所有大于1000公里的海王星外天体都有卫星，这对年轻的太阳系的月球形成理论来说是一个重要的限制。
Evidence for a possible bimodal distribution of the nodal distances of the extreme trans-Neptunian objects: avoiding a trans-Plutonian planet or just plain bias?
A critical step toward the emergence of planets in a protoplanetary disk consists in accretion of planetesimals, bodies 1-1000 km in size, from smaller disk constituents. This process is poorly understood partly because we lack good observational constraints on the complex physical processes that contribute to planetesimal formation. In the outer solar system, the best place to look for clues is the Kuiper belt, where icy planetesimals survived to this day. Here we report evidence that Kuiper belt planetesimals formed by the streaming instability, a process in which aerodynamically concentrate…
Observational Constraints on Planet Nine: Astrometry of Pluto and Other Trans-Neptunian Objects
我们使用冥王星和其他TNO的天体测量来限制Batygin和Brown（2016）假设的可能的额外行星（行星九）的天空位置，距离和质量。我们发现，在广阔的天空区域，包含一个巨大的，遥远的行星降低了适合的观测。然而，在其他地区，通过增加这样一颗行星，拟合得到了显著改善。我们的最佳拟合表明，一颗行星的质量比Batygin和Brown（2016）基于遥远的海王星外天体的轨道分布（或Fienga et al.（2016）基于卡西尼飞船测量的距离）所认为的更大或更近。倾向于更大和更近的扰动行星的趋势是由冥王星天体测量的残差驱动的，使用现代恒星目录（Buie和Folkner 2015）从照相板重新测量，这表明在20年的时间里，在decliter中有一个明显的趋势，这驱动了对大扰动的偏好。虽然这种趋势可能是观测中未知来源的系统误差的结果，但一个可能的解决方案是，这种deconstructive趋势可能是由于来自一个天体的扰动，除了第九行星之外，它更接近冥王星，但质量比第九行星小。
Using data from the Infrared Array Camera on the Spitzer Space Telescope, we present photometric observations of a sample of 100 trans-Neptunian objects (TNOs) beyond 2.2 μm. These observations, collected with two broad-band filters centered at 3.6 and 4.5 μm, were done in order to study the surface composition of TNOs, which are too faint to obtain spectroscopic measurements. With this aim, we have developed a method for the identification of different materials that are found on the surfaces of TNOs. In our sample, we detected objects with colors that are consistent with the presence of smal…
Probing close-in satellites of Trans-Neptunian Objects through thermal and direct size measurements
Instituto de Astrofísica de Andalucía, IAA-CSIC（安达卢西亚天体物理研究所）；Deutsches Zentrum für Astrophysik (DZA)（德国天体物理学中心）；Max-Planck-Institut für extraterrestrische Physik（马克斯·普朗克地外物理学研究所）
Looking at the orbits of small bodies with large semimajor axes, we are compelled to see patterns. Some of these patterns are noted as strong indicators of new or hidden processes in the outer Solar System, others are substantially generated by observational biases, and still others may be completely overlooked. We can gain insight into the current and past structure of the outer Solar System through a careful examination of these orbit patterns. In this chapter, we discuss the implications of the observed orbital distribution of distant trans-Neptunian objects (TNOs). We start with some cauti…
We analyze the uncertainty in grain size estimation of pure methane (CH4) and nitrogen saturated with methane (N2:CH4) ices, the most abundant volatile materials on trans-Neptunian objects (TNOs) and Kuiper belt objects (KBOs). We compare the single scattering albedo, which determines the grain size estimation of outer solar system regolith (Hansen, 2009), of these ices using the Mie scattering model and two other Hapke approximations (Hapke, 1993) in radiative transfer scattering models (RTM) at near-infrared (NIR) wavelengths (1-5 $μ$m). The equivalent slab (Hapke Slab) approximation model p…
Trans-Neptunian Binary Mutual Events in the 2020s and 2030s
Florida Space Institute, University of Central Florida（佛罗里达太空研究所，中佛罗里达大学）；Lowell Observatory（洛厄尔天文台）；Northern Arizona University（北亚利桑那大学）；Brigham Young University Department of Physics & Astronomy（杨百翰大学物理与天文学系）
Reflection spectroscopy in the Near Infrared (NIR) is used to investigate the surface composition of Trans-Neptunian objects (TNOs). In general, these spectra are difficult to interpret due to the low apparent brightness of the TNOs, causing low signal-to-noise ratio even in spectra obtained with the largest telescopes available on the Earth, making necessary to use filtering techniques to analyze and interpret them. The purpose of this paper is to present a methodology to analyze the spectra of TNOs. Specifically, we aim at filtering these spectra in the best possible way: maximizing the remo…
Colors and taxonomy of Centaurs and Trans-Neptunian Objects
对半人马座和海王星外天体（TNO）表面性质的研究提供了有关外太阳系早期条件和演化的重要信息。由于大多数这些遥远的冰体都很微弱，测光目前是调查其中统计上重要数量的最佳技术。我们的目标是研究大样本外太阳系小天体的颜色特性，并确定它们的分类。我们分别利用甚大望远镜（欧洲南方天文台）的FORS 2和ISAAC仪器对半人马座和TNO进行了可见光和近红外测光。使用G模式分析，我们根据Barucci et al.（2005 a）系统推导出分类学分类。我们报告了31个天体的光度观测，其中10个天体的颜色是首次报道。28个半人马和TNOs已被分配到一个分类。我们将整个样本的38个对象（28个对象来自这项工作，10个对象来自DeMeo et al. 2009 a）与以前分类的TNOs和半人马结合起来，寻找分类和动态之间的相关性。我们比较了我们的光度测量结果的文献数据，发现暗示的异质性表面的4个对象。
