2024-07-10 ミシガン大学
Concept illustration of a comet floating in space. Image credit: Nicole Smith, made with Midjourney
＜関連情報＞
- https://news.umich.edu/the-origins-of-dark-comets/
- https://www.sciencedirect.com/science/article/abs/pii/S0019103524002677
暗黒彗星の動力学的起源と進化経路の提案 The dynamical origins of the dark comets and a proposed evolutionary track
Aster G. Taylor, Jordan K. Steckloff, Darryl Z. Seligman, Davide Farnocchia, Luke Dones, David Vokrouhlický, David Nesvorný, Marco Micheli
Icarus Available online: 6 July 2024
DOI:https://doi.org/10.1016/j.icarus.2024.116207
Highlights
- The recently-defined “dark comets” may have two source populations.
- A truncated rotational fragmentation cascade explains their observed properties.
- This mechanism produces a unique and testable size-frequency distribution.
- A significant fraction of near-Earth objects may originate from this pathway.
- The material strengths of the dark comets are consistent with comets and asteroids.
Abstract
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 6 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.
