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A new era in the Yarkovsky effect detection on near-Earth asteroids

Presentation #310.02 in the session Asteroids: Dynamics (Oral Presentation)

Published onOct 23, 2023
A new era in the Yarkovsky effect detection on near-Earth asteroids

The Yarkovsky effect is the most important non-gravitational perturbation affecting the dynamics of asteroids smaller than about 30 km. It is a thermal effect caused by non-isotropic re-emission of heat, and it mainly produces a drift in the semimajor axis. This perturbation is typically small, and its estimation can be attempted by means of orbit determination only under certain circumstances, i.e. when the observational arc is long enough and the observations are of good quality.

Estimating the Yarkovsky effect is useful for different reasons. For instance, it can help in the physical characterization of asteroids, or in determining global properties of the near-Earth asteroids (NEAs) population. From a planetary defence point of view, it is fundamental to correctly evaluate the impact threat of a NEA, because the Yarkovsky effect may change the location of the impact keyhole. Several previous works were dedicated to the determination of the Yarkovsky effect on NEAs, however an automatic procedure for the update of the catalogue is not in place yet.

In this work, we present an algorithm for the automatic detection of the Yarkovsky effect on NEAs. The procedure is based on three steps: 1) shortlist of candidates for Yarkovsky detection; 2) orbit determination on the shortlisted candidates; 3) validation of the detections. Step 1 is done by estimating a probability density function (PDF) of the expected Yarkovsky semi-major axis drift, and an NEA is shortlisted by using a statistical criterion. At Step 2, the orbit determination is similar to that of Farnocchia et al. 2013. Finally, at step 3) a detection is accepted or rejected by using again a statistical comparison based on the expected drift of Step 1.

Among the known NEAs, the algorithm identified 361 positive Yarkovsky effect detections, increasing the current set by about 25%. The automatization of this process is a crucial step in light of the beginning of the operational activities of new surveys such as the LSST and the ESA Flyeye Telescope, and the availability of new large sets of data opens up new possibilities in asteroid research. The procedure is now adopted by the ESA NEO Coordination Centre, and data are automatically made available on the web portal ( https://neo.ssa.esa.int/).

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