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Rotational Study of 5:3 and 7:4 Resonant Objects within the Main Classical Trans-Neptunian Belt

2024; Institute of Physics; Volume: 5; Issue: 4 Linguagem: Inglês

10.3847/psj/ad2933

2632-3338

Audrey Thirouin, Scott S. Sheppard,

Planetary Science and Exploration

Abstract The 5:3 and 7:4 mean motion resonances of Neptune are at 42.3 and 43.7 au, respectively, and overlap with objects in the classical trans-Neptunian belt (Kuiper Belt). We report the complete/partial lightcurves of 13 and 14 trans-Neptunian objects (TNOs) in the 5:3 and 7:4 resonances, respectively. We report a most likely contact binary in the 7:4 resonance, 2013 FR 28 , with a periodicity of 13.97 ± 0.04 hr and a lightcurve amplitude of 0.94 ± 0.02 mag. With a V-/U-shaped lightcurve, 2013 FR 28 has one of the largest well-sampled TNO amplitudes observed with ground-based observations, comparable to the well-determined contact binary 2001 QG 298 . 2013 FR 28 has a mass ratio q ∼ 1 with a density ρ ∼ 1 g cm −3 . We find several objects with large amplitudes and classify 2004 SC 60 , 2006 CJ 69 , and 2013 BN 82 as likely contact binaries and 2001 QF 331 , 2003 YW 179 , and 2015 FP 345 as likely elongated objects. We observe the 17:9 resonant or classical object 2003 SP 317 that we classify as a likely contact binary. A lower estimate of 10%–50% and 20%–55% for the fraction of (nearly) equal-sized contact binaries is calculated in the 5:3 and 7:4 resonances, respectively. Surface colors of 2004 SC 60 , 2013 BN 82 , 2014 OL 394 , and 2015 FP 345 have been obtained. Including these colors with ones from the literature reveals that elongated objects and contact binaries share the same ultrared surface color, except Manwë–Thorondor and 2004 SC 60 . Not only are the colors of the 7:4 and 5:3 TNOs similar to the cold classicals, but we demonstrate that the rotational properties of the 5:3 and 7:4 resonants are similar to those of the cold classicals, inferring a clear link between these subpopulations.