The Emission Spectrum of the Hot Jupiter WASP-79b from HST/WFC3

Here we present a thermal emission spectrum of WASP-79b, obtained via Hubble Space Telescope Wide Field Camera 3 G141 observations as part of the PanCET program. As we did not observe the ingress or egress of WASP-79b’s secondary eclipse, we consider two scenarios: a fixed mid-eclipse time based on the expected occurrence time, and a mid-eclipse time as a free parameter. In both scenarios, we can measure thermal emission from WASP-79b from 1.1 to 1.7 μm at 2.4σ confidence consistent with a 1900 K brightness temperature for the planet. We combine our observations with Spitzer dayside photometry (3.6 and 4.5 μm) and compare these observations to a grid of atmospheric forward models that span a range of metallicities, carbon-to-oxygen ratios, and recirculation factors. Given the strength of the planetary emission and the precision of our measurements, we found a wide range of forward models to be consistent with our data. The best-match equilibrium model suggests that WASP-79b’s dayside has a solar metallicity and carbon-to-oxygen ratio, alongside a recirculation factor of 0.75. Models including significant H− opacity provide the best match to WASP-79b’s emission spectrum near 1.58 μm. However, models featuring high-temperature cloud species—formed via vigorous vertical mixing and low sedimentation efficiencies—with little day-to-night energy transport also match WASP-79b’s emission spectrum. Given the broad range of equilibrium chemistry, disequilibrium chemistry, and cloudy atmospheric models consistent with our observations of WASP-79b’s dayside emission, further observations will be necessary to constrain WASP-79b’s dayside atmospheric properties.

Supplemental Material: Zircon (U-Th)/He thermochronology of Grand Canyon resolves 1250 Ma unroofing at the Great Unconformity and <20 Ma canyon carving

All geologic and thermochronologic constraints used in the forward models, major forward model results from the zircon radiation damage accumulation and annealing model (ZRDAAM) of Guenthner et al. (2013), and alternative HeFTy forward model result using different sample inputs.<br>

On the Use of Evidence and Goodness-of-fit Metrics in Exoplanet Atmosphere Interpretation

In exoplanet atmosphere analyses, a suite of retrievals, with and without different chemical components, is often run, with forward models generated across their parameter space. I discuss here potential pitfalls in the interpretation of the statistics of such setups, suggesting a few simple tests to consider when interpreting their results.

Graph-based prior and forward models for inverse problems on manifolds with boundaries

This paper develops manifold learning techniques for the numerical solution of PDE-constrained Bayesian inverse problems on manifolds with boundaries. We introduce graphical Matérn-type Gaussian field priors that enable flexible modeling near the boundaries, representing boundary values by superposition of harmonic functions with appropriate Dirichlet boundary conditions. We also investigate the graph-based approximation of forward models from PDE parameters to observed quantities. In the construction of graph-based prior and forward models, we leverage the ghost point diffusion map algorithm to approximate second-order elliptic operators with classical boundary conditions. Numerical results validate our graph-based approach and demonstrate the need to design prior covariance models that account for boundary conditions.

Supplemental Material: Zircon (U-Th)/He thermochronology of Grand Canyon resolves 1250 Ma unroofing at the Great Unconformity and <20 Ma canyon carving

All geologic and thermochronologic constraints used in the forward models, major forward model results from the zircon radiation damage accumulation and annealing model (ZRDAAM) of Guenthner et al. (2013), and alternative HeFTy forward model result using different sample inputs.<br>

Supplemental Material: Zircon (U-Th)/He thermochronology of Grand Canyon resolves 1250 Ma unroofing at the Great Unconformity and <20 Ma canyon carving

All geologic and thermochronologic constraints used in the forward models, major forward model results from the zircon radiation damage accumulation and annealing model (ZRDAAM) of Guenthner et al. (2013), and alternative HeFTy forward model result using different sample inputs.<br>

Supplemental Material: Zircon (U-Th)/He thermochronology of Grand Canyon resolves 1250 Ma unroofing at the Great Unconformity and <20 Ma canyon carving

All geologic and thermochronologic constraints used in the forward models, major forward model results from the zircon radiation damage accumulation and annealing model (ZRDAAM) of Guenthner et al. (2013), and alternative HeFTy forward model result using different sample inputs.<br>

Supplemental Material: Zircon (U-Th)/He thermochronology of Grand Canyon resolves 1250 Ma unroofing at the Great Unconformity and <20 Ma canyon carving

All geologic and thermochronologic constraints used in the forward models, major forward model results from the zircon radiation damage accumulation and annealing model (ZRDAAM) of Guenthner et al. (2013), and alternative HeFTy forward model result using different sample inputs.<br>