大型超快自转近地小行星(436724) 2011 UW158的动力学行为与表面特征
Dynamical Behavior and Surface Features of Large Super-Fast Rotator Near-Earth Asteroid (436724) 2011 UW158
- São Paulo State University (UNESP)（圣保罗州立大学）
- Observatório Nacional (ON/MCTI)（国家天文台）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究通过三维形状模型和热物理建模，分析了超快自转小行星2011 UW158的动力学环境，发现内聚力维持其结构并保留赤道巨石，同时引入等效不稳定速度量化表面不稳定性，并评估站位保持机动成本。
AI中文摘要：
亚公里级超快自转且具有潜在危险的小行星(436724) 2011 UW158，其自转周期为0.61072小时，由此驱动了极端动力学环境。利用三维多面体形状模型，我们研究了在无内聚力和有内聚力修正条件下的表面动态稳定性，同时探讨了该快速自转、不规则天体区域中的周期轨道族、站位保持机动和能量状态。结果表明，在考虑内聚力后，有效坡度降至约45°，使得赤道附近能够保留最大尺寸约50米的巨石。有效势中离心项的支配地位使外部平衡点向内移动，形成高度不稳定的地质势区域，松散风化层易被抛射，从而阻止了极区以外的长期表面留存。为量化这种不稳定性，我们引入了等效不稳定速度（$v_{\mathrm{ei}}$），将传统逃逸速度分析扩展到超快自转体领域。这些结果与2011 UW158内部存在显著内聚力相一致，使其能够在超过经典自转屏障的旋转应力下保持结构完整性。此外，热物理建模揭示，超快自转产生近乎均匀的表面温度分布。最后，我们应用球谐函数方法计算小行星周围的周期轨道族，以在降低计算成本的同时评估站位保持机动的燃料消耗。总体而言，本研究刻画了2011 UW158的动力学环境，有助于理解近期在LSST巡天图像中发现的超快自转小行星。
英文摘要：
The sub-kilometer Super-Fast Rotator and Potentially Hazardous Asteroid (436724) 2011 UW158 exhibits an extreme dynamical environment driven by its rotational period of 0.61072 h. Using a 3-D polyhedral shape model, we investigate the surface dynamic stability under both cohesionless and cohesion-modified conditions, while also addressing families of periodic orbits, station-keeping maneuvers, and energy states in this rapidly rotating, irregular-body regime. Our results show that, with the inclusion of cohesion, the effective slopes decrease to ~45°, permitting the retention of boulders with maximum sizes of ~50 m near the equatorial region. The dominance of the centrifugal term in the effective potential shifts the exterior equilibrium points inward, creating highly unstable geopotential regions where loose regolith is susceptible to ejection, preventing long-term surface retention outside the polar regions. To quantify this instability, we introduce the equivalent instability speed ($v_{\mathrm{ei}}$), extending conventional escape speed analyses to the SFR regime. These results are consistent with significant internal cohesion in 2011 UW158, which enables the body to maintain structural integrity under rotational stresses exceeding the classical spin barrier. Additionally, thermophysical modeling reveals that the super-fast rotation produces a nearly uniform surface temperature distribution. Finally, we apply a spherical harmonics method to compute families of periodic orbits around the asteroid to assess the fuel cost of station-keeping maneuvers at reduced computational cost. Overall, this study characterizes the dynamical environment of 2011 UW158, contributing to the understanding of Super-Fast Rotator asteroids recently identified in LSST survey images.
