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

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 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°(1σ) from J2000 Ecliptic coordinates (λ=208°, β=+77°) or J2000 Equatorial Coordinates (R.A.=248°, decl.=+58°). The sidereal period is refined to Psid=445.683±0.007 h. The convex shape model is irregular, with maximum dimensions of 60.8, 39.1, and 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 of pV=0.043±0.002. The derived phase curve supports a D-type classification for Leucus.