Sinking Silicates I: Characterizing the benchmark system containing the T0 brown dwarf CWISE J210640.16+250729.0 using JWST

In this study, we present the full (97.3% complete) 0.8--12.5 μ m spectral energy distribution (SED) of an L/T transition object, CWISE J210640.16+250729.0 (CW2106), using the James Webb Space Telescope (JWST). We provide a full characterization of the host star's elemental abundances and age. We empirically derive the bolometric luminosity (L bol about-4.825) of CW2106, and obtain estimates of its mass (M about50-62 M Jup), radius (R about0.83-0.87 R Jup), effective temperature (T eff about1213 K), and surface gravity (g about5.28 dex). We find the near-infrared (near-IR) spectrum (0.8-2.5 μ m) is best reproduced with cloudy atmospheric models while the mid-infrared (mid-IR) spectrum (5-12.5 μ m) is best reproduced with cloudless models. This suggests a cloud layer restricted to only the deepest observable parts of the atmosphere and is qualified by the lack of a 9 μ m silicate feature. Making use of the Mg/Si ratio of the primary, alongside thermochemical models, we predict the clouds in CW2106 to be composed primarily of enstatite (MgSiO 3), removing about23% of the bulk oxygen out of the atmosphere. Future retrieval studies will be able to help investigate the existence and full impact of these cloud species.