发表机构
NASA Goddard Space Flight Center; Northern Arizona University; Stuttgart Technical University of Applied Science; European Southern Observatory（美国国家航空航天局戈达德太空飞行中心; 北亚利桑那大学; 斯图加特应用技术大学; 欧洲南方天文台）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过UKIRT-WFCAM开展近红外分光光度调查，分析122颗近地小天体的分类多样性，发现观测到的分类以S型和CX型为主，去偏后内在种群以碳质天体为主，揭示了碳质物质的大气幸存情况，为行星防御等提供依据。
AI 中文摘要
近地小天体（NEO）是流星和陨石的直接来源种群，为内太阳系的成分与动力学演化提供了直接观测窗口。然而，它们尺寸小、自转速率快、可观测窗口短，长期以来限制了系统的成分表征。我们呈现了2016年至2024年间利用UKIRT-WFCAM仪器对新发现NEO开展的多年快速响应近红外分光光度测量调查结果。本项目共获取371组观测序列，得到122颗NEO的可靠测光测量值和概率性分类结果，这些NEO的直径范围为5米至150米，中位数尺寸为60米。我们采用经过光变曲线校正的Z、J、H和K波段测光，以及基于机器学习的分类框架，推导了观测到的和去偏后的分类分布随天体尺寸的变化关系。观测到的分类占比显示，小NEO种群以S型复合体和CX型复合体天体为主，二者比例近乎相等。然而，在考虑观测选择偏差后，推断出的内在种群实则以暗色碳质（CX型复合体）天体为主，这对小NEO种群的内在成分具有重要意义。我们进一步探究了小NEO、陨石降落统计数据与大气过滤效应之间的关系，发现相当一部分碳质物质可能无法在大气进入过程中幸存。这些结果凸显了对小NEO开展去偏调查对于解读陨石记录、优化主带天体输送模型、为未来任务目标选择及行星防御策略提供依据的重要性。
英文摘要
Small near-Earth objects (NEOs) represent the immediate source population of meteors and meteorites and provide a direct window into the compositional and dynamical evolution of the inner Solar System. However, their small sizes, rapid rotation rates, and short observability windows have historically limited systematic compositional characterization. We present results from a multi-year rapid-response near-infrared spectrophotometric survey of recently discovered NEOs conducted with the UKIRT-WFCAM instrument between 2016 and 2024. Our campaign obtained 371 observation sequences, yielding reliable color measurements and probabilistic taxonomic classifications for 122 NEOs, with diameters ranging from 5 m to 150 m and a median size of 60 m. We employed lightcurve-corrected Z, J, H, and K photometry and a machine-learning-based classification framework to derive both observed and debiased taxonomic distributions as a function of object size. The observed taxonomic fractions show a population of small NEOs dominated by S-complex and CX-complex objects in nearly equal proportions. After accounting for observational selection biases, however, the inferred intrinsic population is instead dominated by dark, carbonaceous (CX-complex) bodies, with important implications for the intrinsic composition of the small NEO population. We further explore the relationship between small NEOs, meteorite fall statistics, and atmospheric filtering effects, finding that a substantial fraction of carbonaceous material likely does not survive atmospheric entry. These results highlight the importance of debiased surveys of small NEOs for interpreting the meteorite record, refining delivery models from the main belt, and informing the selection of future mission targets and planetary defense strategies.
CommentsAccepted for publication in PSJ, 18 pages, 8 figures
