Thermal emission from the hot Jupiter WASP-103 b in J and Ks bands

Hot Jupiters, particularly those with temperature higher than 2000 K, are the best sample of planets that allow in-depth characterization of their atmospheres. We present here a thermal emission study of the ultrahot Jupiter WASP-103 b observed in two secondary eclipses with CFHT/WIRCam in J and K-s bands. By means of high precision differential photometry, we determine eclipse depths in J and K-s to an accuracy of 220 and 270 ppm, which are combined with the published HST/WFC3 and Spitzer data to retrieve a joint constraints on the properties of WASP-103 b dayside atmosphere. We find that the atmosphere is best fit with a thermal inversion layer included. The equilibrium chemistry retrie v al indicates an enhanced C/O (1.35(-0.17)(+0.14) ) and a supermetallicity with [Fe/H]= 2. 19(-0 .63)(+ 0.51) composition. Given the near-solar metallicity of WASP-103 of [Fe/H] = 0.06, this planet seems to be similar to 100 more abundant than its host star. The free chemistry retrie v al analysis yields a large abundance of FeH, H-, CO2, and CH4. Additional data of better accurac y from future observations of JWST should pro vide better constraint of the atmospheric properties of WASP-103b.