New Yarkovsky drift detections using astrometric observations of NEAs

Abstract

The Yarkovsky drift represents the semi-major axis variation of a celestial body due to the Yarkovsky effect. This thermodynamic effect acts more significantly on bodies with a diameter between \(\approx 10 \,\text {m}\) and \(\approx 30 \,\text {km}\). Therefore, the orbits of many minor bodies of the solar system are affected: knowing the value of the Yarkovsky drift can be crucial to accurately predict their positions, especially if the asteroids are Near Earth Asteroids (NEAs) and there may be a non-zero impact probability with the Earth. The direct computation of this effect is not easily achieved due to the scarce availability of NEAs physical information. Thus, the more promising method to estimate the Yarkovsky effect is through an orbital fit using seven parameters, the six orbital elements and a seventh parameter accounting for non-gravitational interactions. In this paper, we show the analysis of 1262 NEAs with Signal-to-Noise Ratio (SNR) greater or equal 2, of which 279 have the parameter S (absolute ratio between the Yarkovsky drift and its expected value) less than 1.5 and are therefore more reliable. Among these, 91 are not present in the literature, thus represent new Yarkovsky drift detections. Furthermore, we used our results to estimate the ratio of the retrograde over prograde rotators and to validate the dependence of the Yarkovsky drift from the diameter, da/dt \(\approx D^{-1}\).