Constraints on TESS albedos for five hot Jupiters

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(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(g) < 0.445 and A(g) < 0.368, respectively. We find that WASP-43 b and WASP-18 b are both consistent with low geometric albedos (A(g) < 0.16) even though they lie at opposite ends of the hot Jupiter temperature range with equilibrium temperatures of similar to 1400 K and similar to 2500 K, respectively. We report self-consistent atmospheric models that explain broad-band 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.

Automated summary

Photometric observations of transiting exoplanets can provide important information on their thermal emission and albedos. In this study, we analyze photometric measurements of five hot Jupiters observed with TESS and derive constraints on their geometric albedos. We find that two of the hot Jupiters have particularly low albedos.