GaiaDR3: A sharp window into physical properties of asteroids

The first photometric measurements from the ESA's Gaia mission [1] were released in April 2018 as part of the second data release (DR2, [2]). Although the dataset contained astrometry and photometry only for about 14,000 asteroids [3], we were still able to successfully derive physical models for almost 200 asteroids, containing mostly new solutions [4]. The utilized physical model includes rotation period, orientation of the spin axis and the 3D shape model. We used a convex inversion method based on the inversion of photometric measurements.

The recent Gaia data release 3 (DR3, [5]) from June 2022 provided a significantly larger amount of photometric measurements - typically a few tens of individual measurements for >150,000 asteroids (>3,000,000 photometric data points in total).

We downloaded the data from the Gaia archive and processed them following the same procedure as in the case of the DR2 data. From all ∼150,000 asteroids, 60,945 have 21 or more observations and we used them for period search with a convex shape model parametrized by spherical harmonics. After carefully setting up the modeling procedure to assure the reliability of derived models, we obtained a final set of 7,370 asteroids with reliable models, which is about twice the number of asteroids with currently known models.

In this contribution, we will show the reliability of our results by comparing them with previous independent studies (i.e., derived from different photometric datasets). Moreover, our dataset of spin states and shapes is based on photometry from a single source, therefore it should not be as biased as the previous one that relies on multi-source data with very different properties. We will show clear evidence of non-gravitational forces shaping the rotation periods and spin axis directions in the asteroid belt (see Figure) as well as other correlations between various physical and orbital properties such as elongation, distance to the Sun, membership to collisional families or size.

[1] Gaia Collaboration, Prusti, T., de Bruijne, J. H. J., et al. 2016, A&A, 595, A1

[2] Gaia Collaboration, Brown, A. G. A., Vallenari, A., et al. 2018a, A&A, 616, A1

[3] Gaia Collaboration, Spoto, F., Tanga, P., et al. 2018b, A&A, 616, A13

[4] Durech, J. & Hanus, J. 2018, A&A, 620, A91

[5] Tanga, P., Pauwels, T., Mignard, F., et al. 2022, arXiv e-prints, 2206.05561