Thermal emission spectra of the ultra-hot Jupiter WASP-33 b

Observations of exoplanetary atmospheres provide critical insights into their chemical composition, formation, and evolution history. Ultra-hot Jupiters serve as excellent targets for atmospheric characterization; studies of these planets may yield key understanding of gas giants' formation and evolution history. We present a thermal emission study of WASP-33,b's dayside atmosphere, based on two secondary eclipse observations with CFHT/WIRCam in two specific narrow band filters, namely the CO and CH4_ ,ppm and 914.3^ _ on filters, and archival data with HST/WFC3 and Spitzer. Stellar pulsations of the host star induce some quasi-periodic photometric variations, particularly in the CH4_ _ on band, which are modeled and corrected in the high-precision differential light curves. An eclipse depth of 1565.2^ +228.6 -237.5 +56.1 -57.0 ,ppm is determined for the CO and CH4_ $= 1.52^ on bands, respectively. Combined with HST/WFC3 and Spitzer data, our joint retrieval of WASP-33 b's dayside atmosphere reveals a high metallicity ( Fe/H +0.35 _ -0.52 $), high C/O ratio (C/O $= 0.78^ +0.03 _ -0.04 $), and a thermal inversion layer, suggesting a formation history involving metal-rich gas accretion. We confirm the presence of the molecules H_2O, H - and CO, and report a tentative detection of TiO in the dayside atmosphere of WASP-33,b. Future higher precision observations with JWST may provide better understanding of constraints on the chemical abundances of oxygen and refractory element abundances to better constrain WASP-33,b's formation and evolutionary pathway.