Near Earth Asteroids with measurable Yarkovsky effect

We seek evidence of the Yarkovsky effect among Near Earth Asteroids (NEAs) by measuring the Yarkovsky-related orbital drift from the orbital fit. To prevent the occurrence of unreliable detections we employ a high precision dynamical model, including the Newtonian attraction of 16 massive asteroids and the planetary relativistic terms, and a suitable astrometric data treatment. We find 21 NEAs whose orbital fits show a measurable orbital drift with a signal to noise ratio (SNR) greater than 3. The best determination is for asteroid (101955) 1999 RQ36, with an SNR ∼ 200. In some cases it is possible to constrain physical quantities otherwise unknown. Furthermore, the distribution of the detected orbital drifts shows an excess of retrograde rotators that can be connected to the delivery mechanism from the most important NEA feeding resonances and allows us to infer the obliquity distribution of NEAs. We discuss the implications of the Yarkovsky effect for impact predictions. In particular, for asteroid (29075) 1950 DA our results favor a retrograde rotation, which may have implications for the 2880 impact threat.

► We find 21 Near Earth Asteroids with measurable Yarkovsky effect.
► Planetary relativistic terms are needed for accurate Yarkovsky detections.
► Inaccurate astrometric schemes may lead to unreliable results.
► Our results are consistent with the Near Earth asteroid delivery mechanism.
► Earth impacts might be driven by the Yarkovsky effect.