Convex Shape and Rotation Model of Lucy Target (11351) Leucus from Lightcurves and Occultations

TL;DR

This study combines lightcurve and occultation data to model the shape, rotation, and physical properties of asteroid Leucus, revealing its irregular shape, rotation period, and surface characteristics.

Contribution

It presents a new convex shape and rotation model of Leucus based on combined observational data, refining its physical and rotational parameters.

Findings

Leucus has a prograde rotation with a specific spin axis orientation.

The rotation period is refined to approximately 445.683 hours.

The shape is irregular with maximum dimensions around 60.8 km.

Abstract

We report new photometric lightcurve observations of the Lucy Mission target (11351) Leucus acquired during the 2017, 2018 and 2019 apparitions. We use these data in combination with stellar occultations captured during five epochs (Buie et al. 2020) to determine the sidereal rotation period, the spin axis orientation, a convex shape model, the absolute scale of the object, its geometric albedo, and a model of the photometric properties of the target. We find that Leucus is a prograde rotator with a spin axis located within a sky-projected radius of 3{\deg} (1$\sigma$) from J2000 Ecliptic coordinates ($\lambda=208\deg$, $\beta=+77\deg$) or J2000 Equatorial Coordinates (RA=248$\deg$, Dec=+58$\deg$). The sidereal period is refined to $P_{sid}=445.683\pm0.007$ h. The convex shape model is irregular, with maximum dimensions of (60.8, 39.1, 27.8) km. The convex model accounts for global features of the occultation silhouettes, although minor deviations suggest that local and global concavities are present. We determine a geometric albedo $p_V=0.043\pm0.002$. The derived phase curve supports a D-type classification for Leucus.