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Rotation state properties in asteroid families: Tracing the dynamical evolution

Presentation #503.04 in the session Asteroids: Main Belt (Oral Presentation)

Published onOct 23, 2023
Rotation state properties in asteroid families: Tracing the dynamical evolution

The recent Gaia data release 3 (DR3, [1]) from June 2022 provided an unprecedented dataset of photometric measurements - typically a few tens of extremely accurate individual measurements for >150,000 asteroids. By analyzing these data by a convex inversion method, [2] derived rotation state properties and relative dimensions for about 8,600 asteroids. Such dataset of physical parameters already confirmed the fingerprints of the Yarkovsky and YORP effects shaping the rotation periods and pole-obliquities within the overall population as well as within individual collisional families.

In this contribution, we aim at combining the DR3 data with another dataset of accurate sparse-in-time photometric measurements - the Asteroid Terrestrial-impact Last Alert System (ATLAS, [3]). This ground-based survey provides hundreds of measurements for >100,000 asteroids. The photometric accuracy is worse compared to the DR3 data, but this is mostly compensated by the larger amount of measurements per asteroid.

Our physical model includes the rotation period, the orientation of the spin axis and the 3D shape model. We used the well-known convex inversion method and perform several steps to select only the most reliable solutions. We derived about 16,000 unique spin state and shape solutions. This dataset of physical properties is particularly suitable for searches for correlations as it is based on photometry from just two well-defined sources. Therefore, it should not be as biased as the previous datasets that rely on multi-source data with very different properties. Interestingly, our dataset contains a larger fraction of slow rotators, such objects were often missed due to sampling bias.

We will show our analysis of physical properties within the whole population as well as within several collisional families. Among others, we build on the suggestions of [4], who report that rotation period distributions differ between the cores and outskirts of some collisional families and that the lightcurve amplitude distributions in families could be correlated with the family age. We will show evidence that older families have a larger fraction of asteroids with P=10–24 h and with rounder shapes (smaller a/b ratio), which likely indicates a more evolved population in the period due to YORP spin down.

[1] Tanga, P., Pauwels, T., Mignard, F., et al. 2023, A&A, 674, A12

[2] Durech, J., Hanus, J. 2023, A&A, 675, A24

[3] Tonry, J. L., Denneau, L., Heinze, A. N., et al. 2018, PASP, 130, 064505

[4] Szabó, G. M., Pál, A., Szigeti, L., et al. 2022, A&A, 661, A48

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