Particle Ejection Contributions to the Rotational Acceleration and Orbit Evolution of Asteroid (101955) Bennu
Abstrakt
This paper explores the implications of the observed Bennu particle ejection events for that asteroid's spin rate and orbit evolution, which could complicate interpretation of the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) and Yarkovsky effects on this body's spin rate and orbital evolution. Based on current estimates of particle ejection rates, we find that the overall contribution to Bennu's spin and orbital drift is small or negligible as compared to the Yarkovsky and YORP effects.
However, if there is a large unseen component of smaller mass ejections or a strong directionality in the ejection events, it could constitute a significant contribution that could mask the overall YORP effect. This means that the YORP effect may be stronger than currently assumed.
The analysis is generalized so that the particle ejection effect can be assessed for other bodies that may be subject to similar mass loss events. Further, our model can be modified to address different potential mechanisms of particle ejection, which are a topic of ongoing study.
Plain Language Summary The near-Earth asteroid Bennu has been observed to be ejecting particles of rock from its surface. The possible effect of these particle ejections on the asteroid's spin rate and orbit is studied using numerical modeling.
We show that the effect is likely minimal, although for certain ejection geometries, their effect on the spin rate could be more important. The loss of mass caused by the particle ejections would likely limit the asteroid's rotational acceleration, suggesting that the acceleration effect on this body may be larger than assumed.
We consider how different mechanisms of ejection could be modeled using our approach.