The Dynamical Origins of the Dark Comets and a Proposed Evolutionary Track

So-called ‘dark comets’ are small, morphologically inactive near-Earth objects (NEOs) that exhibit nongravitational accelerations inconsistent with radiative effects. These objects exhibit short rotational periods (minutes to hours), where measured. We find that the strengths required to prevent catastrophic disintegration are consistent with those measured in cometary nuclei and expected in rubble pile objects. We hypothesize that these dark comets are the end result of a rotational fragmentation cascade, which is consistent with their measured physical properties. We calculate the predicted size-frequency distribution for objects evolving under this model. Using dynamical simulations, we further demonstrate that the majority of these bodies originated from the 𝜈6 resonance, implying the existence of volatiles in the current inner main belt. Moreover, one of the dark comets, (523599) 2003 RM, likely originated from the outer main belt, although a JFC origin is also plausible. These results provide strong evidence that volatiles from a reservoir in the inner main belt are present in the near-Earth environment.

所谓的‘暗彗星’是一类体积较小、形态上无活动迹象的近地天体（NEOs），其表现出的非引力加速度与辐射效应不符。在已完成测量的案例中，这类天体的自转周期极短，仅为数分钟至数小时。我们发现，防止其发生灾难性瓦解所需的结构强度，与彗星核测得的强度以及砾石堆天体的理论预期强度相符。我们推测，这类暗彗星是自转碎裂级联过程的最终产物，这一结论与它们已测得的物理属性相一致。我们针对该模型下演化的天体，计算了其预测的尺寸-频率分布。通过动力学模拟，我们进一步证实，这类天体中的绝大多数起源于ν6共振区域，这意味着当前的内主小行星带中存在挥发物。此外，其中一颗暗彗星(523599) 2003 RM很可能起源于外主小行星带，尽管木星族彗星（JFC）起源的假说也具有合理性。上述研究结果为内主小行星带储层中的挥发物存在于近地环境中提供了强有力的证据。