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The JAXA/Hayabusa2 rendezvoused with the (162 173) Ryugu asteroid from June 2018 to November 2019, performing an artificial impact experiment on 5th April 2019. The goal of this work is to study the photometric properties' variation of the target area (latitude 7–10°N; longitude 303–305°E) after the artificial impact experiment. This is done by applying an empirical method based on the statistical analysis of the Optical Navigation Camera (ONC)'s data set (in particular, of the v band, centred at 0.55  |$\mu$| m), similar to that applied to other asteroids explored by space missions and to the NIRS3 data set of Ryugu. The method was firstly applied on the entire data set acquired between March and April 2019, covering most of the Ryugu surface. The retrieved average phase function of Ryugu is very similar to that obtained on the NIRS3 data set, according to the similar visible and near-infrared albedo values. Nevertheless, this phase function is flatter than other asteroids belonging to the same Ryugu taxonomic class. This can be attributed to the higher spatial resolution of Hayabusa2 observations, which flattens the phase function of dark asteroids by minimizing the effects of shadowing, as confirmed by photometric studies of other asteroids. Then, the photometric properties of the artificial impact crater area revealed a slight phase function steepening and narrowing after the impact: this could indicate that the exposed surface has a larger roughness and more porous particles. [ABSTRACT FROM AUTHOR]

The dynamics of binary asteroid systems are referred to as the full two-body problem (F2BP), which is one of the principal problems in astrodynamics. The gravitational interactions, including the mutual potential, force, and torque, are necessary quantities to acquire the solution of F2BP. However, it is usually difficult to balance accuracy with efficiency of the evaluations, due to the highly irregular shapes of the asteroids and the close distance between the two components. In this paper, a global model is proposed for evaluating the interactions between two polyhedral asteroids with arbitrary separating distances. First, the interactions are represented as the double surface integrals through the iterated divergence theorem, which is lossless. The integrals over the complex boundaries of bodies are then converted to the sum of subdomain integrals over triangular facets which are compatible with the polyhedron model. Finally, these integrals are conveniently approximated through the numerical quadrature. This work provides a general solution that avoids the divergence problem of most traditional models. The benchmarking tests against the exact solution between two ellipsoids verify its high precision even if the bodies are almost touching. Considering asteroids with irregular shapes, we investigate the evolution of the Moshup–Squannit system and compare the results with the traditional series-based model. The developed model makes a reasonable balance between accuracy and efficiency with different quadrature strategies. The simulations show that the developed model achieves a comparable precision with the 4th-order series solution and a relatively fast computation speed with an appropriate quadrature strategy. [ABSTRACT FROM AUTHOR]

Characterized by a composition that highlights extensive geochemical differentiation processes, basaltic asteroids are considered fragments of differentiated bodies. To study the smallest bodies in this population, an important tool is the photometric phase curve that can exhibit different behaviours according to the surface properties of the body. We present here the phase curves obtained for 10 V-type asteroids, nine belonging to the main belt population and one a near-Earth object, with observations acquired at the Observatório Astronômico do Sertão de Itaparica (Brazil). Different behaviours of the phase curves were found, as already obtained by studies of polarimetric curves. Adding to our results in the phase curves of 20 V-types from the literature, we found behaviours not expected for objects of moderate to high albedo in the opposition effect region. We attribute this result to the way regoliths are distributed on the surface of small asteroids, which are different from those of larger objects, although the surface composition is the same. [ABSTRACT FROM AUTHOR]

The ground-based characterization of asteroids is a key step for planning their exploration. The near-Earth asteroid 155140 (2005 UD) is a potential flyby target of Japan Aerospace Exploration Agency's DESTINY + (Demonstration and Experiment of Space Technology for INterplanetary voYage with Phaethon fLyby and dUst Science) mission, while (612267) 2001 SG286 has been considered as a possible target for in-situ exploration. We aim to determine their physical properties using the observations obtained with various telescopes from Canary Islands Observatory. For 2005 UD, we confirmed the two peak light curve, a rotation period of 5.224 |$\pm$| 0.003 h and an amplitude of 0.34 mag. However, a three peak solution seemed also to fit the light curve, but this was discarded as implausible. Using the obtained visible to near-infrared spectrum we classified it as a Cb type, and we found a spectral matching with heated carbonaceous chondrite meteorites of CM2 type. The thermal emission flux at 2.2  |$\mu \mathrm{ m}$| points to an albedo of |$p_V = 0.06~\pm ~0.02$|⁠. There are significant differences in the spectrum of 2005 UD compared to that of (3200) Phaeton, hypothesized as its parent body. The accurate visible spectrum obtained with the Gran Telescopio Canarias indicate that 2001 SG286 is an S-type asteroid. The photometric data obtained with Isaac Newton Telescope suggest a rotation period of 12.30 |$\pm$| 0.01 h and an amplitude of 0.64 mag. With these observations we found its absolute magnitude |$H$|  = 21.4 |$\pm$| 0.3, and estimate its size as 160 |$\pm$| 45 m. [ABSTRACT FROM AUTHOR]

We present photometric data of five near-Earth asteroids (NEAs) obtained in the framework of the NEO Rapid Observation, Characterization, and Key Simulations (NEOROCKS) project. The selected asteroids are (351545) 2005 TE15, (438908) 2009 XO, (501647) 2014 SD224, 2015 FC35, and 2016 CO247. Light curves were obtained for all the asteroids using the 0.46-m TAR2 telescope at the Teide Observatory (OT), and spectrophotometric data in g, r, i , z |$_s$| filters were obtained for asteroids (438908) 2009 XO and (501647) 2014 SD224 using the MuSCAT-2 instrument attached to the 1.52-m Carlos Sanchez Telescope also at the OT. We derived the rotational period of the five NEAs using Fourier series analysis of the rotational light curves. We found |$P = 10.6035 \pm 0.0010$| h for (351545) 2005 TE15, |$7.9140 \pm 0.006$| h for (501647) 2014 SD224, |$3.4211 \pm 0.0075$| h for 2015 FC35, and |$4.800 \pm 0.005$| h for 2016 CO247. We observed two periodic variations for (438908) 2009 XO, a long one with two possible periods of |$P_1 = 157.2 \pm 0.4$| h and |$P_2 = 304.0 \pm 0.4$| h and a large amplitude of 0.881 mag, and a short one with a period of |$P = 13.448 \pm 0.008$| h. Radar data suggest that (438908) 2009 XO could be a contact binary and its double period points towards a non-principal axis rotator. Finally, we used the spectrophotometric data to obtain colours and taxonomic classification for (438908) 2009 XO and (501657) 2014 SD224, concluding that both NEAs are S-type objects. [ABSTRACT FROM AUTHOR]

To incorporate the gravitational influence of Kuiper belt objects (KBOs) in planetary ephemerides, uniform-ring models are commonly employed. In this paper, for representing the KBO population residing in Neptune's 2:3 mean motion resonance (MMR), known as the Plutinos, we introduce a three-arc model by considering their resonant characteristics. Each 'arc' refers to a segment of the uniform ring and comprises an appropriate number of point masses. Then the total perturbation of Plutinos is numerically measured by the change in the Sun–Neptune distance (⁠|$\Delta d_{\mathrm {SN}}$|⁠). We conduct a comprehensive investigation to take into account various azimuthal and radial distributions associated with the resonant amplitudes (A) and eccentricities (e) of Plutinos, respectively. The results show that over a 100-yr period: (1) at the smallest |$e=0.05$|⁠ , the Sun–Neptune distance change |$\Delta d_{\mathrm {SN}}$| caused by Plutinos decreases significantly as A reduces. It can deviate from the value of |$\Delta d_{\mathrm {SN}}$| obtained in the ring model by approximately 100 km; (2) as e increases in the medium range of 0.1–0.2, the difference in |$\Delta d_{\mathrm {SN}}$| between the arc and ring models becomes increasingly significant; (3) at the largest |$e\gtrsim 0.25$|⁠ , |$\Delta d_{\mathrm {SN}}$| can approach zero regardless of A , and the arc and ring models exhibit a substantial difference in |$\Delta d_{\mathrm {SN}}$|⁠ , reaching up to 170 km. Then the applicability of our three-arc model is further verified by comparing it to the perturbations induced by observed Plutinos on the positions of both Neptune and Saturn. Moreover, the concept of the multiple-arc model, designed for Plutinos, can be easily extended to other MMRs densely populated by small bodies. [ABSTRACT FROM AUTHOR]

The stability of spatial orbits around the triangular libration points in the ephemeris model of the Earth–Moon system is studied. Five contributions are made: (1) practical stable spatial orbits in the ephemeris Earth–Moon system lasting thousands of years or even longer are first reported, and spatial stable regions are identified. (2) The mechanism that shapes the boundaries of the spatial stable regions is investigated, and is found to be related to resonances among the precession rates of the lunar orbit, the precession rates of the small body, the mean orbital motion of the Sun, and the libration frequency of the co-orbital motion. (3) Influence on the spatial stable regions from the solar radiation pressure is studied. It is found that the spatial stable region generally shrinks with increasing solar radiation pressure strength. Dust grains with sizes of millimetres in magnitude or smaller generally escape in hundreds of years while objects with larger sizes can stay for thousands of years or even longer; (4) difference between the bi-circular problem model and the ephemeris model in describing the spatial stable regions is presented. (5) The observation of possible objects in the spatial stable orbits is discussed. With the public's growing interest in the cislunar space, the current study is a good attempt to enhance the understanding of the practical orbital dynamics in the cislunar space. [ABSTRACT FROM AUTHOR]

On the dwarf planet Ceres, there are bright spots known as faculae. Four types of faculae are distinguished: (a) floor faculae, (b) faculae on Ahuna Mons, (c) rim/wall faculae found on craters' rims or walls, and (d) ejecta faculae in the form of bright ejecta blankets. Our investigation on the interaction of the hypothesized subsurface originated jet of gas and the granular material indicated that floor faculae (a) could be a result of separation of fine bright component of regolith. Here, we consider the hypothesis that the ejecta faculae (d) may be the result of separation of grains due to explosive gas expansion during the formation of the impact crater. We consider the axisymmetric gas motion above the surface of Ceres. We transform our system of equations into a dimensionless form. Our numerical model indicates that the separation effect is strong enough to separate the grains (according to size, density, and other aerodynamics properties). In some cases, separation gives a monotonic, systematic effect: smaller particles are ejected farther than heavier particles. Generally, however, the distance over which the particles will be thrown depends in a rather complicated way on the parameters of the particles and the parameters of motion of the gas. This property fits the faculae of type (d). Because we used the dimensionless form of the equations, our results can be also applied to other celestial bodies where the regolith contains volatile substances. This paper is an extension of our investigations on the origin of faculae (a). [ABSTRACT FROM AUTHOR]

Estimates of the frequency of planetary systems in the Milky Way are observationally limited by the low-mass planet regime. Nevertheless, substantial evidence for systems with undetectably low planetary masses now exists in the form of main-sequence stars that host debris discs, as well as metal-polluted white dwarfs. Further, low-mass sections of star formation regions impose upper bounds on protoplanetary disc masses, limiting the capacity for terrestrial or larger planets to form. Here, we use planetary population synthesis calculations to investigate the conditions that allow planetary systems to form only minor planets and smaller detritus. We simulate the accretional, collisional, and migratory growth of |$10^{17}$|  kg embryonic seeds and then quantify which configurations with entirely sub-Earth-mass bodies (⁠|$\lesssim\!\! 10^{24}$|  kg) survive. We find that substantial regions of the initial parameter space allow for sub-terrestrial configurations to form, with the success rate most closely tied to the initial dust mass. Total dust mass budgets of up to |$10^2 \ \mathrm{ M}_{\oplus }$| within 10 au can be insufficiently high to form terrestrial or giant planets, resulting in systems with only minor planets. Consequently, the prevalence of planetary systems throughout the Milky Way might be higher than what is typically assumed, and minor planet-only systems may help inform the currently uncertain correspondence between planet-hosting white dwarfs and metal-polluted white dwarfs. [ABSTRACT FROM AUTHOR]

Binary systems comprise approximately 15 per cent of the near-Earth asteroid population, yet thermal-infrared (IR) data are often interpreted for these bodies as if they are single objects. Thermal-IR light curves of binary asteroids (3905) Doppler and (175706) 1996 FG3 are analysed using an adaptation of the Advanced Thermophysical Model, deriving new constraints on their thermal inertias as |$\Gamma = 114 \pm 31\, \, \mathrm{J}\, \mathrm{m}^{-2}\, \mathrm{K}^{-1}\, \mathrm{s}^{-1/2}$| and |$\Gamma = 142 \pm 6\, \, \mathrm{J}\, \mathrm{m}^{-2}\, \mathrm{K}^{-1}\, \mathrm{s}^{-1/2}$|⁠ , respectively. We determine that this adapted model is suitable for binary systems where their primary rotation to secondary orbit period ratios can be approximately characterized by small integers. Objects with more complex orbital states require a model with alternative temperature convergence methodologies. Thermal inertia is shown to have a strong effect on binary thermophysical light-curve morphology, introducing significant modulations both inside and outside of mutual event times. The depths of eclipse events are shown to be suppressed at longer wavelengths due to the sensitivity to cooler parts of the surface, meanwhile surface roughness is shown to have little effect on the thermal light-curve morphology. A proof of concept model for the (65803) Didymos system is demonstrated, showing how such a binary model could be used to study the system during the European Space Agency's Hera mission, and the applicability of this adapted model to NASA's Lucy mission is also briefly discussed. [ABSTRACT FROM AUTHOR]

Asteroid 2016 HO |$_3$|⁠ , a small asteroid (<60 m) in super fast rotation state (⁠|$\sim$| 28 min), and is the target of China's Tianwen-2 asteroid sample-return mission. In this work, we investigate its structural stability using an advanced soft-sphere-discrete-element-model code, dembody , which is integrated with bonded-aggregate models to simulate highly irregular boulders. The asteroid body is numerically constructed by tens of thousands particles, and then is slowly spun up until structural failure. Rubble piles with different frictions, cohesions, morphologies, grain size distributions, and structures are investigated. We find a 2016 HO |$_3$| shaped granular asteroid would undergo tensile failure at higher strengths as opposed to shear failure in lower strengths, regardless of its shape and constituent grain size ratio. In the tensile failure regime, the critical tensile strength is proportional to the square of the spin rate, but surprisingly, is independent of the internal friction angle. Such relations indicate that the Maximum Tensile Stress criterion emerges as superior paradigm for investigating the failure behaviour of fast-rotating asteroids. We predict that the high-spin rate of asteroid 2016 HO |$_3$| requires a surface strength over |$\sim$| 3 Pa and a bulk tensile strength over |$\sim$| 10–30 Pa. Through comparing these strength conditions with the latest data from asteroid missions, we suggest a higher likelihood of a monolithic structure over a typical rubble pile structure. However, the possibility of the latter cannot be completely ruled out. In addition, the asteroid's surface could retain a loose regolith layer globally or only near its poles, which could be the target for sampling of Tianwen-2 mission. [ABSTRACT FROM AUTHOR]

The temporary capture (TC) of Jupiter-family objects has long been a pivotal focus in celestial mechanics research. This study investigates the TC of objects near Jupiter within the context of the planar circular restricted three-body problem (PCRTBP), employing Lagrangian coherent structures (LCSs) and periapsis Poincaré maps. Initially, LCSs are identified via periapsis Poincaré maps and applied to segment the phase space. Parameter scanning enables a detailed analysis, classifying the orbital behaviours of objects in the proximity of Jupiter into three distinct categories: TC, low-energy flyby, and collision, each designating specific regions in phase space. Subsequently, a novel method for screening potential TC objects within the Jupiter system is proposed and validated, informed by the dynamic characteristics of TC motions. The efficacy of this method is illustrated by the re-identification of six known TC comets and the prediction of a prospective TC asteroid, 2002 GV28. Within the framework of the PCRTBP, analogous TC trajectories for these comets and asteroids are identified, offering novel insights into the dynamics of TC events. [ABSTRACT FROM AUTHOR]

Asteroids pose significant threats to Earth, necessitating early detection for potential deflection. Leveraging machine learning (ML), we classify asteroids into near-Earth Asteroids (particularly Atens, Amors, Apollos, and Apoheles) and non-near-Earth asteroids, further categorizing them based on hazard potential. Training the seven models on a comprehensive data set of 4687 asteroids, we achieve high accuracy in prediction. The predictive capability of these models is critical for informed decision-making in planetary defense strategies. We apply different regularization techniques to prevent overfitting and validate the models using a large unseen data set. A rigorous long-term N -body integration spanning 1 Myr is executed utilizing the Mercury N -body integrator to illuminate the evolution of asteroid properties over extended temporal scales. Following this integration process, the best-performing ML model is employed to classify asteroids based on their orbital characteristics and hazardous status respectively. Our findings highlight the effectiveness of ML in asteroid classification and prediction, paving the way for large-scale applications. By dividing a 1 Myr integration into intervals, we uncover temporal trends in asteroid behaviour, revealing insights into hazard evolution and ejection patterns. Notably, initially, hazardous asteroids tend to transition to non-hazardous states over time, elucidating key dynamics in planetary defense. We illustrate these findings through plotted graphs, providing valuable insights into asteroid dynamics. These insights are instrumental in advancing our understanding of long-term asteroid behaviour, with significant implications for future research and planetary protection efforts. [ABSTRACT FROM AUTHOR]

We present an analysis of a stellar occultation event caused by a near-Earth asteroid (98943) 2001 CC21, an upcoming flyby target in the Hayabusa2 extended mission, on 2023 March 5. To determine the asteroid's shape from diffraction-affected light curves accurately, we developed a novel data-reduction technique named the Diffracted Occultation's United Simulator for Highly Informative Transient Explorations (DOUSHITE). Using DOUSHITE-generated synthetic models, we derived constraints on (98943) 2001 CC21's shadow shape from the single-chord occultation data. Our results suggest a significant elongation of the shadow with an axis ratio of |$b/a = 0.37\pm 0.09$|⁠. This shape could be crucial for planning Hayabusa2's high-speed flyby to optimise the limited imaging opportunities. [ABSTRACT FROM AUTHOR]

In an attempt to further characterize the near-Earth asteroid (NEA) population, we present 38 new light curves acquired between 2020 September and 2023 November for NEAs (7335) 1989 JA, (7822) 1991 CS, (154244) 2002 KL6, and (159402) 1999 AP10, obtained from observations taken at the Teide Observatory (Tenerife, Spain). With these new observations along with archival data, we computed their first shape models and spin solutions by applying the light-curve inversion method. The obtained rotation periods are in good agreement with those reported in previous works, with improved uncertainties. Additionally, besides the constant period models for (7335) 1989 JA, (7822) 1991 CS, and (159402) 1999 AP10, our results for (154244) 2002 KL6 suggest that it could be affected by a Yarkovsky–O'Keefe–Radzievskii–Paddack acceleration with a value of |$\upsilon \simeq -7\times 10^{-9}$| rad d |$^{-2}$|⁠. This would be one of the first detections of this effect slowing down an asteroid. [ABSTRACT FROM AUTHOR]

Particle–particle and particle–gas processes significantly impact planetary precursors such as dust aggregates and planetesimals. We investigate gas permeability (⁠|$\kappa$|⁠) in 12 granular samples, mimicking planetesimal dust regoliths. Using parabolic flights, this study assesses how gravitational compression – and lack thereof – influences gas permeation, impacting the equilibrium state of low-gravity objects. Transitioning between micro- and hyper-gravity induces granular sedimentation dynamics, revealing collective dust–grain aerodynamics. Our experiments measure |$\kappa$| across Knudsen number (Kn) ranges, reflecting transitional flow. Using mass and momentum conservation, we derive |$\kappa$| and calculate pressure gradients within the granular matrix. Key findings: (i) As confinement pressure increases with gravitational load and mass flow, |$\kappa$| and average pore space decrease. This implies that a planetesimal's unique dust-compaction history limits subsurface volatile outflows. (ii) The derived pressure gradient enables tensile strength determination for asteroid regolith simulants with cohesion. This offers a unique approach to studying dust-layer properties when suspended in confinement pressures comparable to the equilibrium state on planetesimals surfaces, which will be valuable for modelling their collisional evolution. (iii) We observe a dynamical flow symmetry breaking when granular material moves against the pressure gradient. This occurs even at low Reynolds numbers, suggesting that Stokes numbers for drifting dust aggregates near the Stokes–Epstein transition require a drag force modification based on permeability. [ABSTRACT FROM AUTHOR]

We have studied the evolution of near-Earth asteroid (NEA) families and pairs to inform future searches. To do so, we integrated clusters of simulated NEAs with different initial conditions, namely the orbital inclination, ejection speed, and the effects of mean-motion resonances on the parent body prior to breakup while also varying the orbit, mass, and number of perturbing planetary bodies. We studied the orbital element dispersion rates of NEA family members and found a power-law increase in those families whose orbits brought them close to a planet. This allowed us to conclude that family dispersion is significantly affected by the Kozai–Lidov effect due to oscillations in the eccentricity, and that the rate of dispersion is slowest at high inclination relatively far from the nearest planet. In most cases, the ejection speed of the initial breakup does not affect the dispersion, except within weaker mean-motion resonances where more violent breakups will result in the ejection of a fraction of the asteroids, causing a large increase in dispersion. Within mean-motion resonances, where Kozai–Lidov oscillations are slowed, increases in the dispersion of a family are delayed, leading them to be identifiable for longer. [ABSTRACT FROM AUTHOR]

While the data analysis of γ-ray telescopes has now become more robust, some signals may be misinterpretations of a time-variable foreground emission from the Solar system, induced by low-energy cosmic-ray interactions with asteroids. Our goal is to provide emission templates for this time-variable diffuse γ-ray foreground by considering the populations of Main Belt Asteroids, Jovian and Neptunian Trojans, Kuiper Belt Objects, and the Oort Cloud. We model the spatial distribution of all known asteroids by performing 3D-fits to determine their density profiles and calculate their appearances by line-of-sight integrations. Because Earth and the asteroids are moving with respect to each other, we obtain diffuse emission templates varying on time-scales of days to decades. We find that the temporal variability can lead to flux enhancements that may mimic emission features unless properly taken into account. This variation is further enhanced by the Solar cycle as the cosmic-ray spectrum is attenuated by the Solar modulation potential, leading to a relative flux increase of the outer asteroids. The cumulative effect of the time-dependent emission is illustrated for the case of the '511 keV OSSE fountain', and for emission features near the Galactic Centre, both being possible misinterpretations of the Solar system albedo. We recommend that γ-ray data analyses should always take into account the possibility of a time-variable foreground. Due to the ecliptic overlap with the Galactic plane, the Galactic emission is expected to be weaker by 0.1–20 per cent, depending on time (relative planetary motion), energy, and Solar cycle, which has consequences for the interpretation of dark matter annihilation cross sections, cosmic-ray spectra and amplitudes, as well as nucleosynthesis yields and related parameters. [ABSTRACT FROM AUTHOR]

On 18 May 2024, a superbolide traversed the western part of the Iberian Peninsula, culminating its flight over the Atlantic Ocean and generating significant media attention. This event was caused by a weak carbonaceous meteoroid of 1 m, entering the atmosphere at 40.4 km s |$^{-1}$| with an average slope of 8.5 |$^\circ$|⁠. The luminous phase started at 133 km and ended at an altitude of 54 km. The meteoroid's heliocentric orbit had an inclination of 16.4 |$^\circ$|⁠ , a high eccentricity of 0.952, a semimajor axis of 2.4 au, and a short perihelion distance of 0.12 au. The superbolide was recorded by multiple ground-based stations of the Spanish Fireball and Meteorite Network and the European Space Agency, as well as by the U.S. Government sensors from space. Due to the absence of observable deceleration, we successfully reconciled satellite radiometric data with a purely dynamic atmospheric flight model, constraining the meteoroid's mass and coherently fitting its velocity profile. Our analysis shows a good agreement with the radiant and velocity data reported by the Center for Near-Earth Object Studies, with a deviation of 0.56 |$^\circ$| and 0.1 km s |$^{-1}$|⁠ , respectively. The presence of detached fragments in the lower part of the luminous trajectory suggests that the meteoroid was a polymict carbonaceous chondrite, containing higher-strength macroscopic particles in its interior due to collisional gardening, or a thermally processed C-type asteroid. The orbital elements indicate that the most likely source is the Jupiter-Family Comet region, aligning with the Solar and Heliospheric Observatory comet family, as its sunskirting orbit is decoupled from Jupiter. This event provides important information to characterize the disruption mechanism of near-Sun objects. [ABSTRACT FROM AUTHOR]

White dwarf atmospheres are frequently polluted by material from their own planetary systems. Absorption features from Ca, Mg, Fe, and other elements can provide unique insights into the provenance of this exoplanetary material, with their relative abundances being used to infer accretion of material with core- or mantle-like composition. Across the population of white dwarfs, the distribution of compositions reveals the prevalence of geological and collisional processing across exoplanetary systems. By predicting the distribution of compositions in three evolutionary scenarios, this work assesses whether they can explain current observations. We consider evolution in an asteroid belt analogue, in which collisions between planetary bodies that formed an iron core lead to core- or mantle-rich fragments. We also consider layer-by-layer accretion of individual bodies, such that the apparent composition of atmospheric pollution changes during the accretion of a single body. Finally, we consider that compositional spread is due to random noise. We find that the distribution of Ca, Fe, and Mg in a sample of 202 cool DZs is consistent with the random noise scenario, although 7 individual systems show strong evidence of core-mantle differentiation from additional elements and/or low noise levels. Future surveys that detect multiple elements in each of a few hundred white dwarfs, with well-understood biases, have the potential to confidently distinguish between the three models. [ABSTRACT FROM AUTHOR]

This paper presents a general strategy for tracking the scale-span movement process of asteroid regolith materials. It achieves the tracking of the mass movement on the asteroid at a realistic scale, under conditions of high-resolution asteroid surface topography (submeter level) and actual regolith particle sizes. To overcome the memory exponential expansion caused by the enlarged computational domain, we improved the conventional cell-linked list method so that it can be applied to arbitrarily large computational domains around asteroids. An efficient contact detection algorithm for particles and polyhedral shape models of asteroids is presented, which avoids traversing all surface triangles and thus allows us to model high-resolution surface topography. A parallel algorithm based on Compute Unified Device Architecture for the gravitational field of the asteroid is presented. Leveraging heterogeneous computing features, further architectural optimization overlaps computations of the long-range and short-range interactions, resulting in an approaching doubling of computational efficiency compared to the code lacking architectural optimizations. Using the above strategy, a specific high-fidelity discrete element method code that integrates key mechanical models, including the irregular gravitational field, the interparticle and particle-surface interactions, and the coupled dynamics between the particles and the asteroid, is developed to track the asteroid regolith mass movement. As tests, we simulated the landslide of a sand pile on the asteroid's surface during spin-up. The simulation results demonstrate that the code can track the mass movement of the regolith particles on the surface of the asteroid from local landslides to mass leakage with good accuracy. [ABSTRACT FROM AUTHOR]

The Japanese probe Hayabusa 2 recently visited the NEA (162173) Ryugu. This mission provided valuable information about the asteroid, including in situ images and a surface sample brought back to the Earth. The data suggests that Ryugu has likely been affected by space weathering, but the underlying cause of the surface modification remains unclear. This paper aims to shed light on the problem by providing new information about the possible past orbital path of Ryugu. We used a procedure to estimate how Ryugu has dynamically evolved since it entered the NEAs' region and whether this can explain the observed data. We have conducted numerical integrations of the N -body gravitational problem. The system comprises the Sun, the Solar system's eight planets, and a group of 29 000 test particles initially placed in the main asteroidal belt (MAB) near the ν6 secular resonance. We then tracked the particles that left the MAB and eventually arrived close to Ryugu's current orbit. Our analysis showed that out of 307 clones of Ryugu, only three came very close to the Sun at a distance of less than 0.1 au. Consequently, it is unlikely that Ryugu has undergone significant surface temperature variations. We also computed that ∼70 per cent of the clones have spent more than 5 Myr at an equivalent distance of 1 au from the Sun. This result suggests that Ryugu has been exposed to significant amounts of solar radiation over a long period, which may have resulted in space weathering effects on its surface. [ABSTRACT FROM AUTHOR]

This paper attempts to present a comprehensive analysis of the photopolarimetric properties of asteroids. In light of the limitations identified in several previously employed empirical formulae, this paper introduces a new formula that offers a reliable fit for the phase-polarization curve of asteroids. The validity of the new empirical formula is confirmed by analysing polarimetric data for lunar soil samples across a wide range of phase angles and various spectral bands. Notably, this investigation reveals a strong negative correlation between |$P_{\mathrm{ max}}$| and wavelength (⁠|$\lambda$|⁠) for lunar soil samples. Furthermore, the examination of key features of the phase-polarization curve of asteroids, such as the polarization minimum (⁠|$P_{\mathrm{ min}}$|⁠), polarization maximum (⁠|$P_{\mathrm{ max}}$|⁠), and the slope (h) at the inversion angle, allows us to explore their correlations with the geometric albedo (A) of asteroids. We have investigated whether our photopolarimetric studies could corroborate the existing classification scheme for asteroids, which divides them into three major composition classes: Chondrite (C), Metallic (M), and Stony (S)-types, based on spectral analysis. Our findings have revealed a good agreement with the existing classification. Each class is characterized by a specific combination of geometric albedo (A) and polarimetric properties (⁠|$P_{\mathrm{ min}}$|⁠ , |$P_{\mathrm{ max}}$|⁠ , and h) observed in asteroids, represented by four distinct regions. Interestingly, besides the three main types (C-, M-, and S-), we have found an overlapping region containing both M- and S-type asteroids. [ABSTRACT FROM AUTHOR]

Node secular resonances, or s -type secular resonances, occur when the precession frequencies of the node of an asteroid and some planets are in commensurability. They are important for changing the proper inclination of asteroids interacting with them. Traditionally, identifying the asteroid resonant status was mostly performed by visual inspection of plots of the time series of the asteroid resonant argument to check for oscillations around an equilibrium point. Recently, deep learning methods based on convolutional neural networks (CNNs) for the automatic classification of images have become more popular for these kinds of tasks, allowing for the classification of thousands of orbits in a few minutes. In this work, we study 11 s -type resonances in the asteroid main belt and in the Hungaria region and focus on the four most diffusive ones. Two secular resonances in the Hungaria region, the 2 · s − s 4 − s 6 and the s − 2 · s 6 + s 7 − g 6 + g 8 overlap, but this has negligible effects in terms of chaotic dynamics. Here, we obtained filtered images of the resonant arguments by filtering out all low-frequency signals with a Butterworth filter. A simple method based on amplitudes and periods of librations can perform a preliminary selection of asteroids in librating orbits. Our results show that CNN models applied to filtered images are much more effective in terms of metrics like accuracy, Precision, Recall, and F1-score than those that use images of osculating resonant arguments. Filtered resonant arguments should be preferentially used to identify asteroids interacting with secular resonances. [ABSTRACT FROM AUTHOR]

The orbit solution of near-Earth asteroids heavily relies on ground-based optical observations. The orbit uncertainty is limited by the insufficient observation quantity and quality. The Chinese Tianwen-2 mission targets a near-Earth asteroid (469219) Kamo'oalewa and a main-belt comet, 311P/PANSTARRS. To accurately determine the orbit of Kamo'oalewa, more optical observations are needed. Autonomous observation experiments focusing on Kamo'oalewa were carried out using the 2.16-m telescope at the Xinglong Observatory of the National Astronomical Observatory of China. We found that this telescope could observe near-Earth asteroids as faint as a magnitude of 22.8. Based on the stacking method and trailed star extraction algorithm, 14 optical observations were obtained from 2022 to 2024. The orbit for Kamo'oalewa was determined by combining our observations with historical observations between 2004 and 2024. The inclusion of our observations results in improved orbital uncertainties of Kamo'oalewa by 18.67, 7.93, and 11.12 km (1σ) in the X, Y , and Z directions, respectively. Furthermore, by combining all existing and simulated observations, the uncertainty of the orbital determination of Kamo'oalewa was analysed. When using an additional 180 group observations from 3 Chinese observatories over 2 yr, the orbital uncertainties of Kamo'oalewa in the 3 directions could be reduced to 30 km (1σ). [ABSTRACT FROM AUTHOR]

Potentially Hazardous Asteroids (PHAs) are a special subset of Near-Earth Objects (NEOs) that can come close to the Earth and are large enough to cause significant damage in the event of an impact. Observations and researches of Earth-PHAs have been underway for decades. Here, we extend the concept of PHAs to Mars and study the feasibility of detecting Mars-PHAs in the near future. We focus on PHAs that truly undergo close approaches with a planet (dubbed CAPHAs) and aim to compare the actual quantities of Earth-CAPHAs and Mars-CAPHAs by conducting numerical simulations incorporating the Yarkovsky effect, based on observed data of the main asteroid belt. The estimated number of Earth-CAPHAs and Mars-CAPHAs are 4675 and 16910, respectively. The occurrence frequency of Mars-CAPHAs is about 52 per year, which is 2.6 times that of Earth-CAPHAs, indicating significant potential for future Mars-based observations. Furthermore, a few Mars-CAPHAs are predicted to be observable even from Earth around the time of next Mars opposition in 2025. [ABSTRACT FROM AUTHOR]

We investigate the photometric properties of 35 well-observed asteroids using dense ground-based and sparse ATLAS survey data. Focusing on two-colour photometric phase functions, derived using inverse methods, we explore the wavelength dependence. Our study reveals distinct (G 1, G 2) domains for cyan and orange filters, especially among some S-complex asteroids. For other asteroids, substantial uncertainties prevail, or their distributions of phase curve parameters overlap, precluding definitive conclusions on wavelength dependence. Notably, for S-complex objects, the effect appears systematic, characterized by lower G 2 values in the cyan filter. The effect can be explained by considering the known geometric albedo correlation: higher albedo corresponds to flatter, whereas lower albedo corresponds to steeper phase curves. In the case of equal albedo, asteroids with red spectral slopes have a more pronounced opposition effect in red and asteroids with blue spectral slopes in blue filters. We explore the variation of slope differences of orange and cyan phase curves with phase angle. For most asteroids, the largest nominal variation is observed at phase angles < 10°. This suggests that the phase colouring for the orange–cyan colour slope is more pronounced at small phase angles. Through meticulous analysis of the opposition effect amplitudes, we also pinpoint preferred rotational pole solutions. We identify inconsistencies between phase curve parameters and spectral types in specific cases. The shape- and geometry-corrected phase curves signify an important advancement in studying asteroid photometric behaviour and may offer a deeper understanding of surface and regolith properties previously obscured by these effects, such as surface roughness. [ABSTRACT FROM AUTHOR]

Sparse and serendipitous asteroid photometry obtained by wide field surveys such as the Asteroid Terrestrial-impact Last Alert System (ATLAS) is a valuable resource for studying the properties of large numbers of small Solar System bodies. We have gathered a large data base of ATLAS photometry in wideband optical cyan and orange filters, consisting of 9.6 × 107 observations of 4.5 × 105 main belt asteroids and Jupiter Trojans. We conduct a phase curve analysis of these asteroids considering each apparition separately, allowing us to accurately reject outlying observations and to remove apparitions and asteroids not suitable for phase curve determination. We obtain a data set of absolute magnitudes and phase parameters for over 100 000 selected asteroids observed by ATLAS, |$\sim 66\, 000$| of which had sufficient measurements to derive colours in the ATLAS filters. To demonstrate the power of our data set we consider the properties of the Nysa–Polana complex, for which the ATLAS colours and phase parameters trace the S-like and C-like compositions amongst family members. We also compare the properties of the leading and trailing groups of Jupiter Trojans, finding no significant differences in their phase parameters or colours as measured by ATLAS, supporting the consensus that these groups were captured from a common source population during planetary migration. Furthermore, we identify ∼9000 asteroids that exhibit large shifts in derived absolute magnitude between apparitions, indicating that these objects have both elongated shapes and spin axes with obliquity ∼90 degrees. [ABSTRACT FROM AUTHOR]

The potentially hazardous asteroid 99942 Apophis will have a very close approach to the Earth in 2029. The encounter on its own may provide measurements of Earth's effects on Apophis' surface and also contribute to the improvement of some physical characteristics of the asteroid. In a previous work, we assumed the existence of a hypothetical disc of particles around Apophis before the 2029 encounter, and identified the particles that would escape from the gravity domain of Apophis due to the Earth's gravitational perturbation during the close encounter. In the current work, we investigate the possibility of a meteor activity originating from this event. We study the orbital evolution of these particles computing the MOIDs of the particles with respect to the Earth for the following 200 yr. Our results are not favourable for a meteor activity on Earth. However, a meteoroid activity on the Moon might happen during the encircling period after 88 yr of the 2029 encounter. [ABSTRACT FROM AUTHOR]

Quantifying electron trapping and transfer to small molecules is crucial for interfacial chemistry. In an astrochemical context, we study how NH3 clusters in both crystalline and amorphous forms can capture low-energy electrons to form ammoniated electrons. Electron affinities, vertical detachment energies, and vertical attachment energies were computed via ab initio static and dynamics simulations, (DFT, DLPNO-CCSD(T);AIMD), for (NH3) n clusters (n = 4, 5, 6, 8, 14, 23, and 38). Our results indicate that the clusters could trap and stabilize the unpaired electron which is always externally localized on the clusters. Interactions of the ammoniated electron clusters with astrochemically relevant molecules indicate that electron transfer to water and methanol are feasible, forming the radical anions (H2O)−· and (CH3OH)−·. The trapping of electrons by both crystalline and amorphous NH3 ices, and subsequent transfer to small molecules, highlights 'astro-electrochemical' reactions, and has implications for both astrochemistry as well as terrestrial cluster science. [ABSTRACT FROM AUTHOR]

Combining archival photometric observations from multiple large-area surveys spanning the past 17 years, we detect long-term variability in the light curves of ZTF J032833.52−121945.27 (ZTF J0328−1219), ZTF J092311.41+423634.16 (ZTF J0923+4236), and WD 1145+017, all known to exhibit transits from planetary debris. ZTF J0328−1219 showed an overall fading in brightness from 2011 through to 2015, with a maximum dimming of ≃0.3 mag, and still remains ≃0.1 mag fainter compared to 2006. We complement the analysis of the long-term behaviour of these systems with high-speed photometry. In the case of ZTF J0923+4236 and WD 1145+017, the time-series photometry exhibits vast variations in the level of transit activity, both in terms of numbers of transits, as well as their shapes and depths, and these variations correlate with the overall brightness of the systems. Inspecting the current known sample of white dwarfs with transiting debris, we estimate that similar photometric signatures may be detectable in one in a few hundred of all white dwarfs. Accounting for the highly aligned geometry required to detect transits, our estimates imply that a substantial fraction of all white dwarfs exhibiting photospheric metal pollution from accreted debris host close-in planetesimals that are currently undergoing disintegration. [ABSTRACT FROM AUTHOR]

Physical properties of ten millimetre-sized meteoroids from the Southern Delta Aquariids (SDA) shower are derived using optical observations from the Canadian Automated Meteor Observatory between 2020 and 2023. The meteors are found to ablate in two distinct erosion stages, the second stage showing a single, bright leading fragment. Our modelling interprets these observations as evidence for equal masses of compact grains embedded in a porous, low density matrix. The average bulk density of SDA meteors is found to be 1420 ± 100   |$\rm {kg \ m^{-3}}$|⁠ , with the compact component having a density of 2310 ± 160 |$\rm {kg \ m^{-3}}$| and the porous component a density of 700 ± 110   |$\rm {kg \ m^{-3}}$|⁠. The high bulk density of SDA meteors is comparable to densities found for the Quadrantid and Geminid showers, both of which also have low perihelion distances. This suggests that thermal desorption may play a significant role in the processing of meteoroids. [ABSTRACT FROM AUTHOR]

Statistical analysis of samples of the orbits of celestial bodies is complicated by the fact that the Keplerian orbit is a multidimensional object, the coordinate representation of which non-linearly depends on the choice of orbital elements. In this work, using the construction of the Fréchet mean, concepts of mean orbit and dispersion of the orbit family are introduced, consistent with the distance function on the orbit set. The introduced statistical characteristics serve as analogues of sample mean and variance of a one-dimensional random variable. Exact formulas for calculating the elements of mean orbits and dispersion quantities with respect to two metrics on the orbit space are derived. For a large sample of meteoroid orbits from the Geminid stream, numerical simulations of orbit evolution over 20 000 yr in the past were conducted. By analysing the dependency of statistical characteristics on time, estimates for the age of the stream and the gas outflow velocity are obtained under the assumption of the birth of the Geminids due to the rapid destruction of the cometary nucleus. The estimate of the age of the stream lies in the interval from 1200 to 2400 yr, and the speed of gas outflow at perihelion should have been more than 1.2 km s−1. [ABSTRACT FROM AUTHOR]

The Hera mission will arrive at the Didymos system to study the efficiency of momentum transfer and to further investigate the binary system in great detail after the Double Asteroid Redirection Test (DART) mission impact. We took advantage of two online data bases of meteorites spectra and of recent Didymos spectra taken before and after the DART impact. We performed the first selection based on the comparison of the band centre values of the silicate absorption bands (localized at 1 and 2  μ m) between Didymos and the meteorites. The second selection was made defining a four-dimensional space parameter whose dimensions were the band depth and the slope of the two bands, normalized to Didymos values. We introduced a distance measure to find the closest meteorites to Didymos in this space. Finally, we made the last selection based on other criteria, such as the presence of different spectra of the same meteorite, the presence of different spectra from different data bases, and the comparison with the literature. The result of this work is a list of six meteorites that are the most analogous to Didymos system. We also found out that Didymos is most probably mainly composed of L/LL ordinary chondrites, with a preference for the LL sub-type. From our list of meteorites, we were able to estimate the normalized abundance of olivine and pyroxene of Didymos. Finally, a match between Didymos and OC meteorites was also found in the Mid-InfraRed (MIR) range. [ABSTRACT FROM AUTHOR]

In recent years, the rapid development of exoplanet research has provided us with an opportunity to better understand planetary systems in the universe and to search for signs of life. In order to further investigate the prevalence of habitable exoplanets and to validate planetary formation theories, as well as to comprehend planetary evolution, we have utilized confirmed exoplanet data obtained from the NASA Exoplanet Archive database, including data released by telescopes such as Kepler and TESS. By analyzing these data, we have selected a sample of planets around F, G, K, and M-type stars within a radius range of 1 to 20 R ⊕ and with orbital periods ranging from 0.4 days to 400 days. Using the IDEM method based on these data, we calculated the overall formation rate, which is estimated to be 2.02%. Then, we use these data to analyze the relationship among planet formation rates, stellar metallicity, and stellar gravitational acceleration ( log g ). We firstly find that the formation rate of giant planets is higher around metal-rich stellars, but it inhibits the formation of gas giants when log g > 4.5, yet the stellar metallicity seems to have no effect on the formation rate of smaller planets. Secondly, the host stellar gravitational acceleration affects the relationship between planet formation rate and orbital period. Thirdly, there is a robust power-law relationship between the orbital period of smaller planets and their formation rate. Finally, we find that, for a given orbital period, there is a positive correlation between the planet formation rate and the log g . [ABSTRACT FROM AUTHOR]

By using recent observations of the Dydimos−Dimorphos system from the Hubble Space Telescope , 37 boulders with a size of 4 to 7 m ejected from the system during the impact with the DART spacecraft were identified. In this work, we studied the orbital evolution of a swarm of boulders with a similar size to that of the detected ones. By using recent estimates for the ejection velocity of the boulders, we numerically propagated the dynamics of the swarm for 20 kyr in the future. We found that the ejection velocities and the non-gravitational effects are not strong enough to change the secular evolution significantly. The minimum orbit intersection distance (MOID) with the Earth will be reached in about 2.5 kyr, but it will not fall below 0.02 au. On the contrary, the Mars MOID will be very small in four instances, two near 6 kyr and the other two near 15 kyr. Therefore, there may be a chance for them to impact Mars in the future. Given the rarefaction of the Martian atmosphere, we expect the boulders to arrive intact on the ground and excavate a small impact crater. The results presented here provide a further indication that some meteorites found on Earth originated in collisions of ∼100 m near-Earth asteroids with projectiles of ∼1 m in size. [ABSTRACT FROM AUTHOR]

The minimal sizes of impactors that produced asteroid families were calculated, and their maximal sizes, i.e. the size that corresponds to head-on collisions, were estimated. We used data for 16 large families and the physical parameters of some members of these families available in NASA's JPL updated in 2022. We found that the typical minimal sizes of family-forming impactors were of the order of one-tenth the size of the parent bodies (PBs). The Themis family, for which the ratio of the radii r imp/ R PB = 0.08 and the mass loss is as large as 0.55, presents an example. The families of Juno and Euphrosyne, with the impactor to PB size ratio of an order of 0.01, are rather exceptional. The PBs of Juno and Euphrosyne families lost only 0.0014 and 0.0061 of their mass, respectively. It was found that the double structure of the Vesta family could have originated from two impacts by the bodies with radii as small as about 4 km, at least. [ABSTRACT FROM AUTHOR]

The mutual gravitational interaction of binary asteroids, which make up approximately 15 per cent of the near-Earth asteroid (NEA) population, provides a continuous tidal force, creating ground motion. We explore the potential of kilometre-sized binary asteroids as targets for seismological studies of their interior structure. We use a numerical model wherein each body is constructed of discrete particles interacting via gravity and contact forces. The system's orbital properties are modelled based on those of typical binary NEAs: a secondary body orbits a primary body at a distance of a few to 10 primary radii, resulting in orbital periods of a few tens of hours. We varied the elastic moduli (stiffness) of the constituent particles and measured a strain of a few micrometres caused by the orbiting satellite. Over eight orbital periods, the acceleration of the strain vector along the primary body's equatorial axis indicates that tidally induced ground motion generated by a binary asteroid system is detectable by modern seismometers, like the instruments deployed on the InSight mission to Mars. Owing to the relatively short orbital period of the satellite – a mean of 25.8 h for known binary NEAs – only a modest mission lifetime would be required for a seismometer to adequately characterize an asteroid's interior through tidally induced deformation. Future deployment of seismometers on binary asteroids will allow for a detailed characterization of the structure of these objects. [ABSTRACT FROM AUTHOR]

For fast-rotating asteroids, observed light curves could be very different from real light curves due to long exposure time. We present an improved observed light-curve model that accounts for long exposure time often encountered in observations of fast-rotating asteroids. By integrating brightness over time, we derive a more accurate observed light-curve model, allowing for better shape and spin state inversion results. Our analysis demonstrates that the fast-rotating model is more suitable for spin state inversion with longer exposure time, while the Kaasalainen model suffices for shorter exposure time. For spin state and shape inversion, exposure times of approximately 0.4 P and 0.2 P represent critical thresholds, respectively, beyond which the fast-rotating model exhibits superior performance. Notably, scattering parameters have minimal impact on the shape inversion results. These findings contribute valuable insights to the determination of shape and spin states for fast-rotating asteroids, shedding light on the challenges posed by long exposure time in such investigations. [ABSTRACT FROM AUTHOR]

This work presents novel findings that broaden our understanding of the amount of water that can be transported to the Earth. The key innovation lies in the combined usage of smoothed particle hydrodynamics (SPH) and N -body codes to assess the role of collision fragments in water delivery. We also present a method for generating initial conditions that enables the projectile to impact at the designated location on the target's surface with the specified velocity. The primary objective of this study is to simulate giant collisions between two Ceres-sized bodies by SPH near the ν6 secular resonance and follow the evolution of the ejected debris by numerical N -body code. With our method 6 different initial conditions for the collision were determined, and the corresponding impacts were simulated by SPH. Examining the orbital evolution of the debris ejected after collisions, we measured the amount of water delivered to the Earth, which is broadly 0.001 ocean equivalents of water, except in one case where one large body transported 7 per cent oceans of water to the planet. Based on this and taking into account the frequency of collisions, the amount of delivered water varies between 1.2 and 8.3 ocean's worth of water, depending on the primordial disc mass. According to our results, the prevailing external pollution model effectively accounts for the assumed water content on the Earth, whether it's estimated at 1 or 10 ocean's worth of water. [ABSTRACT FROM AUTHOR]

This work deals with a possible ultraviolet and infrared luminescence of the solid substance of the near-Earth objects. In particular, features of the phenomena of photoluminescence and cathodoluminescence of substance of these objects are considered. It is shown that ultraviolet and infrared luminescence of these objects can be revealed by orbital-based instruments. It is demonstrated that detectability of luminescence of near-Earth objects opens up the possibilities for determination of the physical–chemical properties of their solid substance and finding of the dark small low-albedo bodies, which could approach dangerously closer to the Earth. Equations for calculation of luminescence intensity of these objects are proposed. Data on the luminescence of the corresponding minerals and the numerical values of the yields of luminescence and albedo, as the conditions for the detectability of the luminescence of near-Earth objects are presented as well. [ABSTRACT FROM AUTHOR]

Linear secular resonances happen when there is a commensurability between the precession frequency of the pericenter, g , or longitude of the node, s , of an asteroid and a planet. Non-linear resonances are higher order combinations of these frequencies. Here, we studied the three most diffusive g -type non-linear secular resonances using Artificial Neural Networks. We identified a population of more than 2100 resonant objects in the g − 2 g 6 + g 5 and g − 3 g 6 + 2 g 5 resonances. This allows the creation of a Convolutional Neural Network model for the g − 2 g 6 + g 5 resonance, able to predict the status of several thousands of asteroids in seconds. We identified 12 new possible dynamical groups among the resonant population, including the 5507 and 170776 families, which have both estimated ages of less than 7 Myr. These are the two first-ever identified young families in resonant configurations of the investigated resonances, which allows for setting limits on their original ejection velocity field. [ABSTRACT FROM AUTHOR]

Investigating the hypervelocity impact process on rubble-pile asteroids is crucial for understanding the formation and evolution of small celestial bodies, and has important implications for planetary defence. In recent years, numerical simulations have been widely used to model asteroid impacts, as a complement to experimental and theoretical approaches. In particular, the hybrid SPH–DEM framework has been introduced to describe the multistage dynamics involving shock propagation and gravitational re-accumulation. However, the tension between modelling accuracy and computational costs poses significant challenges in rubble-pile impact simulations. In this study, we introduce two distinct particle configurations, i.e. multiple layers of similar-sized surface contact particles and a set of different-sized gravity particles, to efficiently describe the large irregular boulders during long-term evolution. Accordingly, the new transition algorithms are implemented to convert the smoothed particle hydrodynamics (SPH) results into the desired discrete-element method (DEM) configurations. With the proposed method, the complexity of contact computation is reduced from |$\mathcal {O}(N)$| to |$\mathcal {O}(N^{2/3})$|⁠ , and the gravity computation is accelerated by about one hundred times while maintaining the same level of resolution. The method is then used to simulate the double asteroid redirection test impact on the rubble-pile asteroid Dimorphos. Our numerical simulations have reproduced the observation results regarding momentum transfer and mass ejection. Moreover, we predict that the impact event will form a final crater larger than 45–68 m in diameter and lead to global resurfacing of the target. The renewed surface and fresh interior will be accessible to the upcoming Hera mission, providing new perspectives on the formation and evolution of the rubble-pile binary asteroids. [ABSTRACT FROM AUTHOR]

We apply the Hierarchical Clustering method (HCM) and Selective Backward Integration method (BIM) to search for associated families and young families for all main-belt active asteroids (MBAAs) known to date. We find four newly candidate sub-groups of known families, which include the candidate Brueghel family associated with 176P/LINEAR, the candidate 324P group associated with 324P/La Sagra, the candidate G1 group associated with P/2016 G1, and the candidate Tutenchamun family associated with (62412) 2000 SY178. Additionally, we identify three entirely new candidate families, the Interamnia family associated with P/2021 A5, the candidate 457P group associated with 457P/Lemmon-PANSTARRS, and the candidate Scheila family associated with (596) Scheila. We also reveal two newly identified family associations with known families between 259P/Garradd and the Adeona family, P/2019 A4 and the Jones family. All main-belt comets (MBCs) are likely associated with young and primitive families. Some unstable MBCs, which cannot be identified using HCM, may still originate from young and primitive families. However, due to dynamic diffusion, they cannot be conclusively linked to current families. Impact-disrupted asteroids could be linked with young families and they may change their original spectrum under the impact activity. Rotational fission of young and primitive asteroids might be a useful mechanism for facilitating the exposure of subsurface ice, and therefore triggering sublimation-driven activity. Rapid rotation and sublimation activity mechanisms are likely coupled. Therefore, further research should be made on such fast rotational asteroids that are located in primitive families. [ABSTRACT FROM AUTHOR]

Submicron debris released in interplanetary collisions gets charged in the solar wind and generates disturbances to the magnetic field environment. The unique magnetic field disturbances, named interplanetary field enhancements (IFEs) are recorded by many spacecraft. In this study, we have developed a novel model to trace the IFEs to their origins. By employing this model, we can pinout regions with highly collision frequencies, thereby identifying regions of intense collisional activity. The model can help constrain interplanetary magnetic disturbances and our results can be used to guide part of the interplanetary-object survey. [ABSTRACT FROM AUTHOR]

On 2023 December 12, the star α Orionis will be occulted by asteroid (319) Leona. This represents an extraordinary and unique opportunity to analyse the brightness distribution of Betelgeuse's photosphere with extreme angular resolution by studying light curves from different points on Earth and at different wavelengths. Here we present observations of another occultation by asteroid Leona, on 2023 September 13, whose goal was to determine Leona's projected shape and size in preparation for the December 12th event and its interpretation. The occultation campaign was highly successful with 25 positive detections from 17 different sites and a near miss. The effective diameter in projected area derived from the positive detections was 66 ± 2 km using an elliptical fit to the instantaneous limb. The body is highly elongated, with dimensions of 79.6 ± 2.2 km × 54.8 ± 1.3 km in its long and short axis, respectively, at occultation time. This result, in combination with dense time series photometry of Leona that we recently obtained, together with archival sparse photometry, allowed us to predict the angular size of the asteroid for the Betelgeuse event and to simulate the expected brightness change. Also, an accurate position coming from the occultation is provided, to improve the orbit of Leona. [ABSTRACT FROM AUTHOR]

In this work, we explore how to classify asteroids in co-orbital motion with a given planet using Machine Learning. We consider four different kinds of motion in mean motion resonance with the planet, nominally Tadpole at L 4 and L 5, Horseshoe and Quasi-Satellite , building three data sets defined as Real (taking the ephemerides of real asteroids from the JPL Horizons system), Ideal and Perturbed (both simulated, obtained by propagating initial conditions considering two different dynamical systems) for training and testing the Machine Learning algorithms in different conditions. The time series of the variable θ (angle related to the resonance) are studied with a data analysis pipeline defined ad hoc for the problem and composed by: data creation and annotation, time series features extraction thanks to the tsfresh package (potentially followed by selection and standardization) and the application of Machine Learning algorithms for Dimensionality Reduction and Classification. Such approach, based on features extracted from the time series, allows to work with a smaller number of data with respect to Deep Learning algorithms, also allowing to define a ranking of the importance of the features. Physical interpretability of the features is another key point of this approach. In addition, we introduce the SHapley Additive exPlanations for Explainability technique. Different training and test sets are used, in order to understand the power and the limits of our approach. The results show how the algorithms are able to identify and classify correctly the time series, with a high degree of performance. [ABSTRACT FROM AUTHOR]

Solar system Centaurs originate in trans-Neptunian space from where planet orbit crossing events inject their orbits inside the giant planets' domain. Here, we examine this injection process in the three-body problem by studying the orbital evolution of trans-Neptunian asteroids located at Neptune's collision singularity as a function of the Tisserand invariant, T. Two injection modes are found, one for T > 0.1, or equivalently prograde inclinations far from the planet, where unstable motion dominates injection, and another for T ≤ 0.1, or equivalently polar and retrograde inclinations far from the planet, where stable motion dominates injection. The injection modes are independent of the initial semimajor axis and the dynamical time at the collision singularity. The simulations uncovered a region in the polar corridor where the dynamical time exceeds the Solar system's age suggesting the possibility of long-lived primordial polar trans-Neptunian reservoirs that supply Centaurs to the giant planets' domain. [ABSTRACT FROM AUTHOR]

We analyse the role of the general relativity (GR) on the nodal librations of test particles located at the Habitable Zone (HZ) around a solar-mass star, which evolve under the influence of an eccentric planetary-mass perturber with a semimajor axis of 0.1 au. Based on a secular Hamiltonian up to quadrupole level, we derive analytical criteria that define the nodal libration region of an HZ particle as a function of its eccentricity e 2 and inclination i 2, and the mass m 1 and the eccentricity e 1 of the perturber. We show that an HZ particle can experience nodal librations with orbital flips or purely retrograde orbits for any m 1 and e 1 by adopting a suitable combination of e 2 and i 2. For m 1 < 0.84 MJup, the greater the m 1 value, the smaller the e 2 value above which nodal librations are possible for a given e 1. For m 1 > 0.84 MJup, an HZ test particle can undergo nodal librations for any e 2 and appropriate values of e 1 and i 2. The same correlation between m 1 and e 2 is obtained for nodal librations with orbital flips, but a mass limit for m 1 of 1.68 MJup is required in this case. Moreover, the more massive the inner perturber, the greater the nodal libration region associated with orbital flips in the (e 1, i 2) plane for a given value of e 2. Finally, we find good agreements between the analytical criteria and results from N -body simulations for values of m 1 ranging from Saturn-like planets to super-Jupiters. [ABSTRACT FROM AUTHOR]

We present 24 new dense light curves of the near-Earth asteroids (3103) Eger, (161989) Cacus, (2100) Ra-Shalom, and (12711) Tukmit, obtained with the Instituto Astrofísico Canarias 80 and Telescopio Abierto Remoto 2 telescopes at the Teide Observatory (Tenerife, Spain) during 2021 and 2022, in the framework of projects visible NEAs observations survey and NEO Rapid Observation, Characterization and Key Simulations. The shape models and rotation state parameters (P , λ, β) were computed by applying the light curve inversion method to the new data altogether with the archival data. For (3013) Eger and (161989) Cacus, our shape models and rotation state parameters agree with previous works, though they have smaller uncertainties. For (2100) Ra-Shalom, our results also agree with previous studies. Still, we find that a Yarkovsky–O'Keefe–Radzievskii–Paddack acceleration of υ = (0.223 ± 0.237) × 10−8 rad d−2 slightly improves the fit of the light curves, suggesting that (2100) Ra-Shalom could be affected by this acceleration. We also present for the first time a shape model for (12711) Tukmit, along with its rotation state parameters (P  = 3.484900 ± 0.000031 h, λ = 27° ± 8°, β = 9° ± 15°). [ABSTRACT FROM AUTHOR]