The Yarkovsky effect and bulk density of near-Earth asteroids from Gaia DR3

Abstract

Aims. The primary objective of this study is to utilize Gaia DR3 asteroid astrometry to detect the Yarkovsky effect, a non-gravitational acceleration that affects the orbits of small asteroids. We then computed the bulk densities for the sample of objects for which we obtained an estimation of the Yarkovsky effect. Methods. We used the version of the OrbFit software that is currently developed at the Minor Planet Center (MPC). We utilized the complete astrometric dataset from the MPC, encompassing all radar data and Gaia DR3 observations. The orbital computation was performed for a total of 446 Near-Earth Asteroids (NEAs; including 93 Potentially Hazardous Asteroids (PHAs)), and 54 094 Inner Main Belt Asteroids (IMBAs) as well as Mars Crossing asteroids. Furthermore, we used a new validation method which involved computing the A2 (the Yarkovsky effect) using different observational arcs to observe the stability of the result. We applied the Yarkovsky effect to determine the density of the studied asteroids. Results. Thanks to Gaia DR3 we significantly constrained orbital uncertainties and determined reliable A2 values for 49 Near-Earth Asteroids, including 10 new detections and for all improvements in signal-to-noise ratio. Additionally, we successfully determined the density, along with their uncertainties, for all of these objects. However, regarding IMBAs, although we have made progress, we do not detect Yarkovsky drift for any asteroid in the main belt. Conclusions. Adding a relatively small amount of ultra-precise astrometry from Gaia DR3 to the observations from the Minor Planet Center (MPC) not only significantly improves the orbit of the asteroid but also enhances the detectability of non-gravitational parame ters. Utilizing this improved dataset, we were able to determine the densities, along with their uncertainties, for the studied asteroids. Looking ahead, with the upcoming release of Gaia DR4, we anticipate even more detections for NEAs and new detections for IMBA and Mars Crossing Asteroids.