Presentation #105.03 in the session Physical Properties of Centaurs & KBOs.
Trans-Neptunian objects (TNOs) are icy relics, left-overs, from the planetary formation that orbit the Sun beyond Neptune, as such, the investigation of their properties, is essential to understanding the formation and evolution of the Solar System. The trans-Neptunian objects conform to a diverse population in terms of shape, size, surface color, and geometric albedo. With the launch of the James Webb Space Telescope (JWST) last December, the diversity present in the TNOs can be explored and interpreted in terms of surface composition.
In anticipation of receiving JWST data, we present the results of the study of four TNOs using visible, NIR, and IRAC-Spitzer data. The Spitzer data were obtained in 2016 on IRAC channels 1 (3.6 microns) and 2 (4.5 microns) during a whole rotational period of each body. Our targets, the centaur 2060 Chiron, the resonant TNO 36328 Huya, and the two methane-ice-rich dwarf planets 136199 Eris, and136472 Makemake, belong to different dynamical classes and have albedo values from 0.08 to almost 1. Their sizes also show very different values from approximately 200 to more than 2,000 kilometers. This diversity suggests that their surface chemical and physical properties could reflect a different formation origin or a different evolution, which may be marked by sublimation epochs, collisions, or atmosphere retention.
Our observations were planned so that comparison of the light curve of each body in channels 1 and 2, and also with rotational light curves in the visible and NIR from the literature, would enable us to search for indications of heterogeneities on their surface. Additionally, merging the Spitzer albedo values along one rotation with VNIR spectra from the literature, allows us to perform the compositional analysis of these bodies using the Skuratov modeling technique.
Our modeling results are yet another proof of the diversity present in the trans-Neptunian belt and show definitive clues of how important Webb will be to assess the inventory of ices, complex organics, and silicates in our Solar System.