Constraints on TESS albedos for five hot Jupiters

TL;DR

This study constrains the optical albedos of five hot Jupiters using TESS data, finding low albedos consistent with thermal emission dominance and minimal cloud scattering, and provides first albedo limits for two planets.

Contribution

First constraints on geometric albedos for WASP-50 b and WASP-51 b using TESS, complemented by multi-wavelength atmospheric modeling for two hot Jupiters.

Findings

WASP-43 b and WASP-18 b have low albedos (<0.16).

Data explained by thermal emission with inefficient energy redistribution.

No evidence for clouds or hazes affecting optical scattering.

Abstract

Photometric observations of occultations of transiting exoplanets can place important constraints on the thermal emission and albedos of their atmospheres. We analyse photometric measurements and derive geometric albedo ($A_\mathrm{g}$) constraints for five hot Jupiters observed with TESS in the optical: WASP-18 b, WASP-36 b, WASP-43 b, WASP-50 b and WASP-51 b. For WASP-43 b, our results are complemented by a VLT/HAWK-I observation in the near-infrared at $2.09~\mu$m. We derive the first geometric albedo constraints for WASP-50 b and WASP-51 b: $A_\mathrm{g}<0.445$ and $A_\mathrm{g}<0.368$, respectively. We find that WASP-43 b and WASP-18 b are both consistent with low geometric albedos ($A_\mathrm{g}<0.16$) even though they lie at opposite ends of the hot Jupiter temperature range with equilibrium temperatures of $\sim1400$ K and $\sim2500$ K, respectively. We report self-consistent atmospheric models which explain broadband observations for both planets from TESS, \HST, \Spitzer and VLT/HAWK-I. We find that the data of both hot Jupiters can be explained by thermal emission alone and inefficient day-night energy redistribution. The data do not require optical scattering from clouds/hazes, consistent with the low geometric albedos observed.