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Characterizing the atmospheres of cloud-free T-dwarfs using Gaussian processes

Presentation #305.23 in the session Stars, Cool Dwarfs, Brown Dwarfs — iPoster Session.

Published onJun 29, 2022
Characterizing the atmospheres of cloud-free T-dwarfs using Gaussian processes

Exoplanet atmospheres have a multitude of challenges concerning their characterization. However, non-irradiated, self luminous brown dwarfs are similar in temperature and surface gravity to giant exoplanets, and serve as excellent analogs to help with some of these challenges. We present a grid of cloud-free T-dwarfs covering atmospheres with Teff ∈ [300K,950K], log g ∈ [3.0,5.5], log Z ∈ [-1.0,1.0], C/O ∈ [0.1,0.7], and log Kzz ∈ [2.0,8.0]. We specifically include both C/O and log Kzz to investigate how C/O ratio and vertical mixing influence the atmospheres of cloud free T-dwarfs explain spectroscopic observations. We then analyze low resolution spectra of brown dwarf targets by incorporating a Bayesian inference framework for robust error propagation called Starfish. Typical model analysis ignores uncertainties that arise from model interpolation and assumes residuals that are independent of each other across wavelengths, but this can result in underestimated errors. Starfish propagates interpolation uncertainties into model parameters and models the covariances of error across wavelengths in the spectra. By combining Starfish with our grid-fitting routine, we aim to answer questions about brown dwarf chemical abundances.

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