Physical parameters of selected Gaia mass asteroids

Abstract

Context. Thanks to the Gaia mission, it will be possible to determine the masses of approximately hundreds of large main belt asteroids with very good precision. We currently have diameter estimates for all of them that can be used to compute their volume and hence their density. However, some of those diameters are still based on simple thermal models, which can occasionally lead to volume uncertainties as high as 20-30%. Aims. The aim of this paper is to determine the 3D shape models and compute the volumes for 13 main belt asteroids that were selected from those targets for which Gaia will provide the mass with an accuracy of better than 10%. Methods. We used the genetic Shaping Asteroids with Genetic Evolution (SAGE) algorithm to fit disk-integrated, dense photometric lightcurves and obtain detailed asteroid shape models. These models were scaled by fitting them to available stellar occultation and/or thermal infrared observations. Results. We determine the spin and shape models for 13 main belt asteroids using the SAGE algorithm. Occultation fitting enables us to confirm main shape features and the spin state, while thermophysical modeling leads to more precise diameters as well as estimates of thermal inertia values. Conclusions. We calculated the volume of our sample of main-belt asteroids for which the Gaia satellite will provide precise mass determinations. From our volumes, it will then be possible to more accurately compute the bulk density, which is a fundamental physical property needed to understand the formation and evolution processes of small solar system bodies.

Determination of Rotation Periods for a Large Sample of Asteroids from the K2 Campaign 9

“…The spin and shape modelling of asteroids also requires precise knowledge of the rotational period (Kaasalainen & Torppa 2001). The volume and the density determination becomes possible when photometrically derived rotation period is combined with other techniques like adaptive optics imaging (e.g., Vernazza et al 2018;Carry et al 2019), occultation chord timings (e.g., Durech et al 2011), or thermal infrared observations (e.g., Hanuš et al 2018;Podlewska-Gaca et al 2020). Only a handful of Solar System objects have been visited by spacecrafts giving us a more or less complete picture of their structure: e.g.…”

Probabilistic modeling of asteroid diameters from Gaia DR2 errors

“…We fed the model with the 11,095 Gaia asteroids from Gaia EDR2 for which previous diameter measurements are available from the literature. The list of diameters was compiled from the works of Drummond (2000); Hanuš et al (2013); Nugent et al (2016); Viikinkoski et al (2017); Alí-Lagoa et al (2018); Sanchez et al (2019); Hanuš et al (2020); Herald et al (2020);Podlewska-Gaca et al (2020). Once the relation between the asteroid diameter and σI G , ĪG and σRA is learned via the logistic BART model, we applied it to the list of 2,886 Gaia DR2 asteroids for which we did not find any diameter information.…”