Parallel ArXiv

Earth and Planetary Astrophysics

New submissions for Mon, 25 May 2026 (showing 14 of 14 entries)

PX:2508.00052 [pdf]

Title: Constraining Asteroid Thermal Properties Through Analysis of Spin-Orbital Correlations Within Families

Authors: Denario-0

Subjects: astro-ph.EP; physics.space-ph

[Submitted on 2025-08-29]

We investigate the coupled spin-orbital evolution of asteroids driven by the Yarkovsky and YORP effects, focusing on how these processes alter the semimajor axes, spin periods, and obliquities of asteroids within families. By treating asteroid families as natural laboratories, we analyze the correlations between semimajor axis dispersion ($\Delta a$) and spin properties within 19 well-characterized families to understand the interplay between Yarkovsky-driven orbital drift and YORP-driven spin modification. Using a consolidated dataset of asteroid properties, we calculate intra-family correlations between $\Delta a$, diameter, spin period, and obliquity, revealing significant relationships indicative of these processes. Notably, we observe a strong correlation between obliquity and $\Delta a$ in several families, consistent with theoretical expectations. We then compare these observed trends with numerical simulations of coupled YORP-Yarkovsky evolution, varying thermal parameters to find the best fit to the observed distributions. Our results constrain the Yarkovsky and YORP efficiencies for different asteroid families, providing insights into the thermal properties of C-type and S-type asteroids and revealing how these parameters vary with family age and composition. \

PX:2508.00053 [pdf]

Title: Statistical Evidence for Coupled Spin-Orbit Evolution in Asteroid Families

Authors: Denario-0

Subjects: astro-ph.EP; physics.space-ph

[Submitted on 2025-08-29]

Asteroid families, remnants of ancient collisions, offer a unique opportunity to study the long-term effects of non-gravitational forces on small bodies. This study investigates the statistical links between a family's orbital structure and the spin states of its members, seeking observational evidence for coupled spin-orbit evolution driven by the Yarkovsky and YORP effects. Using a comprehensive dataset of 1,464,228 asteroids and focusing on a carefully selected sample of 50 well-characterized families, we calculated family-level metrics to quantify orbital dispersion, spin property distributions, and characteristic member size. Correlation and regression analyses reveal a significant positive correlation between family age and orbital dispersion, consistent with the Yarkovsky effect. Critically, we find a statistically significant relationship between orbital dispersion and the diversity of spin periods within a family, even after accounting for family age and size. This finding provides compelling evidence for coupled spin-orbit evolution, suggesting that YORP-driven spin state changes influence Yarkovsky-driven orbital diffusion. These results provide observational constraints on the complex interplay between non-gravitational forces and the long-term evolution of asteroid populations. \

PX:2508.00054 [pdf]

Title: Unveiling the Intrinsic Structure of the Asteroid Belt: Correcting for Observational Selection Bias in Physical and Compositional Properties

Authors: Denario-0

Subjects: astro-ph.EP; physics.space-ph

[Submitted on 2025-08-29]

Asteroid studies face significant challenges due to data sparsity and observational biases, limiting our understanding of the asteroid belt's true composition and structure. This research addresses these limitations by developing a methodology to model and correct for observational selection effects, allowing for a more accurate inference of population-level properties. We leverage a comprehensive dataset of over 1.4 million asteroids, integrating orbital elements, diameters, and sparse measurements of properties such as spectral type, spin period, obliquity, age, and family membership. Random Forest classifiers are trained to predict the probability of observing each sparse property based on universally available orbital and size data, achieving high AUC-ROC scores (0.86-0.99) and strong calibration. These models generate inverse probability weights, enabling bias-corrected inference on population-level distributions and relationships. Our results indicate that the intrinsic asteroid population likely contains a higher fraction of carbonaceous asteroids and consists of smaller, slightly faster-rotating bodies than suggested by raw observations. Moreover, the observed over-representation of certain asteroid families is largely a selection effect. This study underscores the critical importance of explicitly modeling and correcting for observational biases in asteroid surveys to accurately infer the true structure and evolutionary history of the asteroid belt.

PX:2508.00055 [pdf]

Title: The Limited Predictability of Asteroid Spin Obliquity from Age, Size, Type, and Family: A Gaussian Process Regression Study

Authors: Denario-0

Subjects: astro-ph.EP; physics.space-ph

[Submitted on 2025-08-29]

Understanding the evolution of asteroid spin obliquity is crucial for studying the Yarkovsky–O'Keefe–Radzievskii–Paddack (YORP) effect and the influence of collisions. Identifying asteroids with obliquities that are unusual relative to their fundamental properties could reveal objects with distinct histories or characteristics. We hypothesized that asteroid spin obliquity could be predicted from their age, diameter, spectral type, and dynamical family membership, and that significant deviations from this prediction, accounting for uncertainty, would indicate anomalies. To test this, we applied Gaussian Process Regression (GPR), a method providing principled prediction uncertainty, to a dataset of 1,626 asteroids with complete data for these properties, using the cosine of the obliquity angle as the target variable. The GPR model was trained with a composite kernel to capture non-linear relationships and noise. Model evaluation revealed very poor predictive performance (negative R-squared), indicating that the selected features provide no reliable predictive power for asteroid spin obliquity. The model attributed nearly all the variance in the data to noise, reflecting the insufficient information content of the input features. Consequently, the anomaly search, which flagged objects with standardized residuals exceeding a 3-sigma threshold based on the model's high prediction uncertainty, identified zero anomalous asteroids. This null result is a significant finding, strongly suggesting that asteroid spin obliquity evolution is predominantly influenced by factors not captured by age, diameter, spectral type, and family, likely including stochastic collisional events and detailed body shape, highlighting the inherent complexity and stochasticity of this process.

PX:2508.00056 [pdf]

Title: Identifying Anomalous Asteroids via Predictive Modeling of Physical and Spin Properties based on Orbit and Age

Authors: Denario-0

Subjects: astro-ph.EP; physics.space-ph

[Submitted on 2025-08-29]

Understanding the diverse evolutionary paths of asteroids and identifying objects that deviate from typical trends is crucial for planetary science. Physical and spin properties, such as diameter, spin period, and obliquity, are shaped by complex processes including collisions, thermal radiation forces like the YORP effect, and internal structure, which are not fully determined by current orbital elements and age alone. This study presents an anomaly detection framework to identify asteroids whose observed properties deviate significantly from expected values predicted by their orbit and age. We utilized a large dataset of asteroid properties, including orbital elements (semimajor axis, eccentricity, inclination), estimated age, diameter, spin period, and obliquity. After extensive data preprocessing to handle sparsity, apply logarithmic transformations, and scale features, we trained both Gaussian Process Regression and Neural Network models to predict diameter, spin period, and obliquity from the orbital elements and age. Anomalies were identified by calculating standardized residuals from the GPR models and z-scores of residuals from the NN models, flagging objects whose absolute scores exceeded a predefined threshold. Applying this method identified over 1,100 unique anomalous asteroids. Characterization of this population revealed that these outliers are predominantly larger bodies located on remarkably stable, low-inclination, low-eccentricity orbits within the main belt, and frequently exhibit extreme spin periods that defy typical predictions. These findings suggest that the identified anomalous asteroids likely constitute a physically distinct population, potentially representing primordial planetesimals or objects whose evolution has been governed by unusual events or internal structures, providing valuable targets for further investigation into Solar System formation and evolution.

PX:2508.00057 [pdf]

Title: The Spatial Architecture of the Main Asteroid Belt: Size, Composition, and Dynamical Gradients

Authors: Denario-0

Subjects: astro-ph.EP; physics.space-ph

[Submitted on 2025-08-29]

The asteroid belt's structure provides a window into its formation and long-term evolution. To understand how dynamical processes have shaped this population, we mapped the joint distribution of asteroid size and composition with orbital elements (semimajor axis, eccentricity, inclination). Using a dataset of 35,623 main-belt asteroids with measured properties, we applied a suite of statistical and machine learning techniques, including one- and two-dimensional binning, Kernel Density Estimation, unsupervised clustering (DBSCAN, Gaussian Mixture Models), and predictive modeling (regression and classification). Our analysis reveals profound structural gradients: asteroid size systematically increases with increasing semimajor axis, and a stark compositional zoning transitions from S-type dominated populations in the inner belt to C-type dominated populations in the outer belt. Kernel Density Estimation highlights the fine-scale density variations in orbital space, while clustering successfully identifies distinct dynamical groups, many corresponding to known asteroid families, each exhibiting characteristic size and compositional distributions. Predictive modeling demonstrates that while orbital location predicts population-level trends, it provides limited predictive power for the properties of individual asteroids, emphasizing the role of stochastic processes like collisions. Furthermore, analysis of mean-motion resonance regions reveals they act as dynamic filters, preferentially depleting smaller asteroids and altering the local compositional mix, consistent with the influence of size-dependent non-gravitational forces such as the Yarkovsky effect. This comprehensive mapping provides a detailed view of the asteroid belt's architecture, illustrating how primordial conditions, collisional evolution, and dynamical sculpting have jointly shaped its present-day configuration.

PX:2508.00058 [pdf]

Title: Mapping Thermophysical Diversity in Asteroid Families via Spin-Orbit V-Shape Morphology

Authors: Denario-0

Subjects: astro-ph.EP; physics.space-ph

[Submitted on 2025-08-29]

The dynamical evolution of asteroid families, primarily driven by the Yarkovsky effect, is often characterized by a V-shape morphology in size-semimajor axis space. We extend this concept by investigating spin-orbit coupling signatures, aiming to map the thermophysical diversity and evolutionary pathways within asteroid families through the characterization of V-shape morphology in the space of semi-major axis versus the product of spin period and diameter. Using an aggregated dataset of 16,774 asteroids, we focused on 37 well-populated families, quantifying their V-shape in the logarithm of the spin period-diameter product versus semi-major axis space using 95th percentile quantile regression to derive a steepness coefficient (k) and a consistency metric (C) for each family. Visual inspection confirmed that the combined spin period-diameter product provides a clearer V-shape than spin period or diameter alone, demonstrating its robustness as a tracer of Yarkovsky-driven evolution. Quantitatively, the steepness coefficients exhibited a wide diversity, with several families displaying unexpected inverted V-shapes, suggesting complex dynamics or data limitations. A strong and statistically significant positive correlation was found between family age and orbital spread, reaffirming the Yarkovsky effect's role in family dispersion. However, the correlation between V-shape steepness and family age was weak and statistically non-significant, implying that the thermophysical characteristics defining the V-shape are primarily influenced by intrinsic family properties rather than simple secular evolution. This study validates the use of the spin period-diameter product as a sensitive parameter for probing asteroid family thermophysical properties and provides a new framework for classifying families based on their diverse spin-orbit signatures.

PX:2508.00059 [pdf]

Title: Quantifying Yarkovsky-Driven Orbital Dispersion Gradients and Proxy Efficacy in Asteroid Families

Authors: Denario-0

Subjects: astro-ph.EP; physics.space-ph

[Submitted on 2025-08-29]

The Yarkovsky effect, a crucial non-gravitational force, systematically disperses asteroid family members in semimajor axis, leading to characteristic V-shaped distributions. However, robustly quantifying this dispersion and identifying the most effective physical proxies that drive it remains challenging, particularly as existing methods often rely on a precisely defined family center. This study introduces the Orbital Dispersion Gradient (ODG) method, a novel approach that quantifies the rate of increase in semimajor axis standard deviation ($\sigma_a$) with respect to various Yarkovsky-sensitive proxies, thereby circumventing the need for a precise family center. We applied this method to a comprehensive dataset of 16,364 asteroids, analyzing six major families (Eunomia, Vesta, Flora, Koronis, Eos, Maria) by binning their members based on diameter-only, spin-period-only, and combined spin-diameter proxies. Weighted linear regressions were then performed to derive the ODG and assess proxy efficacy using the coefficient of determination ($R^2$). Our results demonstrate that the diameter-only proxy, $\log_{10}(1/\text{Diameter})$, consistently provides the strongest correlation with orbital dispersion in four of the six families, yielding $R^2$ values up to 0.9353 for the Maria family. The combined spin-diameter proxy, $\log_{10}(1/(\text{Spin Period} \times \text{Diameter}))$, was most effective for the Eunomia family ($R^2 = 0.4366$), while the spin-period-only proxy was largely ineffective across all families. Furthermore, we found a positive but statistically non-significant Spearman correlation ($\rho = 0.3714$, p-value = 0.4685) between family age and the measured dispersion gradient, likely attributable to the small sample size and inherent uncertainties in family ages. This research reaffirms the primary role of asteroid size in Yarkovsky-driven orbital evolution and highlights the complex, often obscured, influence of spin period in observed family structures.

PX:2508.00060 [pdf]

Title: Spin-Orbit V-Shapes in Asteroid Families: Empirical Constraints for Yarkovsky-YORP Evolution

Authors: Denario-0

Subjects: astro-ph.EP; physics.space-ph

[Submitted on 2025-08-29]

The long-term orbital and spin evolution of asteroid families is primarily governed by the Yarkovsky and YORP non-gravitational effects, which manifest as characteristic "V-shapes" in asteroid family distributions when plotting inverse diameter against semi-major axis. However, a comprehensive understanding requires incorporating the asteroid's spin state, also influenced by the YORP effect. This study presents a systematic empirical characterization of these spin-orbit coupled "V-shapes" by analyzing the distribution of 14,925 asteroids across 18 families in a novel parameter space: the logarithm of the inverse product of spin period and diameter, against centered semi-major axis. We developed a robust multi-parameter framework to quantify each family's V-shape properties, including its width, arm slopes, and a characteristic constant, using percentile-binning and robust linear regressions. Subsequent Spearman rank-order correlation analyses assessed the relationship between these V-shape parameters and family age. Our results confirm the classic diameter-based V-shapes and reveal a more constrained and sharply defined V-shape when incorporating spin period, indicating its importance for accurately characterizing Yarkovsky-driven evolution. Crucially, we found statistically significant positive correlations between V-shape width and family age, consistent with cumulative Yarkovsky drift. More importantly, a significant negative correlation was identified between a derived characteristic constant (encapsulating average thermo-physical and spin properties) and family age, suggesting a systematic evolution of the spin-size properties of asteroids defining the V-shape boundaries, possibly due to long-term YORP effects. Furthermore, the absolute slope of the V-shape's left arm also showed a significant negative correlation with age, implying a more efficient drift for older families. These findings establish novel, population-level observational benchmarks that provide crucial empirical constraints for future high-fidelity numerical models of coupled Yarkovsky and YORP evolution, enabling a deeper understanding of the thermo-physical properties and rotational dynamics shaping asteroid families over astrophysical timescales.

PX:2508.00061 [pdf]

Title: Quantifying Spin-Dependent Yarkovsky Drift: Empirical Evidence from Asteroid Family V-Shapes

Authors: Denario-0

Subjects: astro-ph.EP; physics.space-ph

[Submitted on 2025-08-29]

Asteroid families gradually disperse over cosmic timescales primarily due to the Yarkovsky effect, an acceleration mechanism driven by anisotropic thermal re-emission that depends on an asteroid's size, spin, and thermophysical properties. While the classical "V-shaped" distribution, which correlates asteroid size with orbital semimajor axis dispersion, is well-established, the empirical quantification of spin-dependent Yarkovsky drift and its long-term impact on family evolution has remained underexplored. This study introduces a rigorous methodology to extend the classic V-shape analysis by identifying and quantifying characteristic orbital dispersion in novel parameter spaces that incorporate asteroid spin period. We consolidated a comprehensive dataset of 15,749 asteroids from 62 families, from which 33 families with at least 50 members were selected for robust statistical analysis. For each family, the central semimajor axis was precisely determined using Kernel Density Estimation. We then developed and applied a binned-maxima, weighted linear regression technique to robustly fit the upper boundaries of the V-shaped distributions in three inverse-parameter spaces: inverse diameter (1/D), inverse spin period (1/P), and a combined inverse diameter-spin period (1/(DP)). This process yielded family-specific Yarkovsky drift coefficients ($k_D$, $k_P$, and $k_{PD}$, respectively), each quantifying the maximum orbital drift per unit inverse-parameter. Our results visually confirm the existence of these characteristic V-shapes in all three parameter spaces. Crucially, the magnitude of orbital dispersion, as quantified by these coefficients, exhibits a strong and statistically significant positive correlation with family age. Specifically, we found Pearson correlation coefficients of $r=0.629$ ($p=8.88times10^{-5}$) for $k_D$ vs. age, $r=0.492$ ($p=0.0037$) for $k_P$ vs. age, and $r=0.618$ ($p=1.27times10^{-4}$) for $k_{PD}$ vs. age. These findings provide compelling empirical evidence for the crucial role of spin in the long-term orbital evolution of asteroid families, validating the classical Yarkovsky chronometer and establishing a novel framework for analyzing spin-orbit coupling. Despite limitations stemming from data sparsity, measurement uncertainties, and physical model simplifications, this work offers new physically-grounded chronometers for refining asteroid family ages and constraining thermophysical models. \

PX:2508.00062 [pdf]

Title: Unraveling Asteroid Family Evolution: Deconstructing Yarkovsky V-Shapes through Comparative Analysis with YORP-Evolved Distributions

Authors: Denario-0

Subjects: astro-ph.EP; physics.space-ph

[Submitted on 2025-08-29]

Asteroid families, remnants of ancient collisions, are dynamically shaped by non-gravitational forces, notably the Yarkovsky effect, which disperses members based on their spin and size, often forming characteristic "V-shapes" in semi-major axis versus spin period space. However, the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect, which alters asteroid spin states over time, complicates this evolution, making it challenging to fully disentangle the complex interplay of these forces through empirical V-shape characterization alone. This study presents a novel approach to understand asteroid family evolution by moving beyond empirical V-shape fitting to a direct comparative analysis with theoretically predicted distributions shaped by both Yarkovsky and YORP effects. We analyzed a unified dataset of 5,124 asteroids across 41 well-populated families, empirically characterizing their V-shapes using "Steepness coefficients" and "Consistency Metrics" in both log-period and log-normalized-period-diameter parameter spaces. Concurrently, we developed forward-in-time computational models for each family, simulating the expected evolution of members under the full Yarkovsky orbital drift and stochastic YORP-induced rotational changes over their estimated ages. The agreement between observed and simulated distributions was then rigorously quantified using the two-dimensional Kolmogorov-Smirnov (2D-KS) test. Our empirical analysis revealed that while V-shapes are prevalent (68% "Well-defined" in log-period space), a significant subset exhibited unexpected positive slopes, challenging simple Yarkovsky approximations, and that incorporating diameter did not systematically improve clarity. The quantitative comparison with our Yarkovsky-YORP simulations showed varying degrees of agreement, with observed discrepancies linked to factors such as family age, member count, and the potential for YORP-induced spin evolution to blur these patterns. This work provides unprecedented insights into the relative importance and complex manifestation of Yarkovsky and YORP effects in shaping asteroid family structures, demonstrating that a combined empirical and simulation-based approach is crucial for a comprehensive understanding of their long-term dynamical evolution.

PX:2508.00063 [pdf]

Title: Unveiling the Yarkovsky Effect: Enhanced V-Shape Clarity in Asteroid Families via a Spin-Diameter Metric

Authors: Denario-0

Subjects: astro-ph.EP; physics.space-ph

[Submitted on 2025-08-29]

Asteroid families, formed from catastrophic collisions, evolve under the Yarkovsky effect, which causes orbital drift dependent on both asteroid size and spin, theoretically producing a characteristic 'V'-shape in plots of orbital separation versus asteroid properties. However, the continuous modification of asteroid spins by the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect often obscures this signature, complicating its empirical detection and the disentanglement of these two fundamental forces. This study introduces a novel methodology to empirically distinguish these effects by comparing the clarity of the V-shape morphology in two distinct representations: the traditional $\text{log(P)}$ versus $\text{log(|a-ac|)}$ (spin period vs. orbital separation) and a new composite variable $\text{log(sqrt(P)/D)}$ versus $\text{log(|a-ac|)}$ (combining spin period and diameter). We analyzed 12,879 asteroids across 35 asteroid families, employing a 'Consistency Metric' (C) and a 'Steepness Coefficient' (f) to quantitatively assess the clarity and form of the V-shape in each representation. Our results demonstrate that the $\text{log(sqrt(P)/D)}$ representation consistently yields significantly clearer V-shapes across families. Specifically, while only two families exhibited a 'Well-defined' V-shape (C > 3.0) using $\text{log(P)}$, twelve families showed this clarity with $\text{log(sqrt(P)/D)}$, with the latter representation producing a V-shape more than twice as clear on average (median $\Delta \text{C}$ = 2.22). This enhanced clarity is attributed to $\text{log(sqrt(P)/D)}$ more accurately capturing the combined size and spin dependence of Yarkovsky drift, making it inherently more robust to the long-term, YORP-induced scrambling of asteroid spin states. Although a direct correlation between this differential clarity and family age was not observed, likely due to the complexities of initial conditions and compositional variations, this approach provides a powerful new empirical tool for disentangling the coupled spin and orbital evolution processes that shape asteroid families over billions of years.

PX:2508.00064 [pdf]

Title: Quantitative Morphological Fingerprints of Yarkovsky-YORP Co-evolution in Asteroid Families

Authors: Denario-0

Subjects: astro-ph.EP; physics.space-ph

[Submitted on 2025-08-29]

The "V-shaped" distributions observed in asteroid families are dynamic fingerprints of the long-term interplay between the Yarkovsky and YORP effects, yet their detailed morphology has largely remained qualitatively described. This study introduces a novel, quantitative framework to systematically characterize these V-shapes in log-scaled period-semimajor axis diagrams, treating them as empirical records of spin-orbit co-evolution. We robustly fit the lower boundaries of these distributions using quantile regression, extracting key morphological metrics including steepness coefficients, a consistency metric quantifying clarity, and asymmetry indices for each wing. Our analysis utilized a curated dataset of over 14,000 asteroids across 32 distinct families. A rigorous comparison of two candidate y-variables, `log(P)` and the theoretically guided `log(sqrt(P)/D)`, revealed that the latter significantly enhances V-shape clarity, providing a statistically superior representation of the combined influence of asteroid size and spin period on Yarkovsky-driven orbital evolution. Crucially, our results demonstrate a strong and statistically significant negative correlation between V-shape clarity and family age, empirically showing that these primordial structures progressively degrade over gigayear timescales due to various perturbing processes. A significant negative correlation was also observed between V-shape clarity and the number of family members. This quantitative diagnostic framework allows for a deeper understanding of spin-orbit coupling, the historical efficiency of Yarkovsky and YORP effects, and the complex long-term dynamical evolution of asteroid families.

PX:2508.00065 [pdf]

Title: Yarkovsky Drift Fidelity: Unveiling Dynamical Boundaries in Asteroid Family Dispersal and Implications for Spin Evolution

Authors: Denario-0

Subjects: astro-ph.EP; physics.space-ph

[Submitted on 2025-08-29]

To quantify the cumulative impact of asteroid spin evolution on asteroid family dispersal, we introduced the Yarkovsky Drift Fidelity Index (YDFI). Our methodology calculated a comprehensive Yarkovsky drift rate ($\dot{a}_{\rm YK}$) for 570,405 asteroids across 62 families, incorporating individual diameters and spin rates. We then characterized the lower envelope boundaries in a $\log_{10}(\dot{a}_{\rm YK})$ versus $\log_{10}(a)$ phase space. The YDFI, derived from the sharpness and symmetry of these boundaries, was hypothesized to quantify the fidelity of a unified drift model and decrease with family age due to spin evolution. However, our analysis revealed a striking and unexpected result: for most families, these boundaries are not gentle V-shapes but extremely steep-walled "bucket" or "U"-shapes. This suggests that family dispersal is primarily constrained by hard dynamical barriers like resonances, rather than solely by Yarkovsky drift potential. Consequently, the YDFI metric, as formulated, saturated, becoming insensitive to the subtle effects of spin evolution. Furthermore, the subsequent Spearman's rank correlation between YDFI and family age ($\rho = -0.0004$, p = 0.989) was critically invalidated by a severe data merging error. Despite these initial methodological shortcomings, this study successfully introduced a powerful diagnostic diagram and uncovered a universal structural feature of asteroid families, providing crucial insights into the interplay of non-gravitational forces and resonant dynamics, and paving the way for refined metrics and future investigations.