Sinking silicates: tracing rainout across the LT transition
Abstract
We will target a sample of abundance benchmarked brown dwarfs to create a transformative dataset that will impact substellar, exoplanetary and planetary science. JWST is unique in enabling us to:
- determine the dependence of cloud composition on Mg/Si, [M/H] and C/O to critically test cloud models - track the rain out of oxygen across the 2000 > Teff > 1000 K range to empirically constrain calibrations for bulk C/O ratios from atmospheric observations of (exo)planets and brown dwarfs Determinations of bulk compositions of giant planets are widely regarded as keystone evidence for understanding their formation and that of planetary systems. This work started in the Solar system and it continues to present challenges that limit the precision and accuracy of key diagnostics such as the C/O ratio. Relating measured atmospheric abundances to intrinsic (bulk) composition is not trivial. It requires a sound understanding of mixing, quenching and cloud condensation processes. Critically, this includes clouds that may be hidden from view but none-the-less alter the atmospheric composition. This proposal will address these challenges by targeting a carefully selected sample of substellar benchmark binaries that span the same temperature range as directly imaged exoplanets. These systems will be used to calibrate the impacts of clouds, mixing and non-equilibrium chemistry on the measured atmospheric composition in the context of known bulk compositions determined from their stellar primaries. This project will create an empirical anchor for understanding how bulk compositions are imprinted on atmospheric abundances across a crucial regime of atmospheric physics.- Publication:
-
JWST Proposal. Cycle 2
- Pub Date:
- May 2023
- Bibcode:
- 2023jwst.prop.3670B