We present the detection and characterization of the full-orbit phase curve and secondary eclipse of the ultra-hot Jupiter WASP-33b at optical wavelengths , along with the pulsation spectrum of the host star .
We analyzed data collected by the Transiting Exoplanet Survey Satellite ( TESS ) in sector 18 .
WASP-33b belongs to a very short list of highly irradiated exoplanets that were discovered from the ground and were later visited by TESS .
The host star of WASP-33b is of \delta Scuti-type and shows nonradial pulsations in the millimagnitude regime , with periods comparable to the period of the primary transit .
These completely deform the photometric light curve , which hinders our interpretations .
By carrying out a detailed determination of the pulsation spectrum of the host star , we find 29 pulsation frequencies with a signal-to-noise ratio higher than 4 .
After cleaning the light curve from the stellar pulsations , we confidently report a secondary eclipse depth of 305.8 \pm 35.5 parts-per-million ( ppm ) , along with an amplitude of the phase curve of 100.4 \pm 13.1 ppm and a corresponding westward offset between the region of maximum brightness and the substellar point of 28.7 \pm 7.1 degrees , making WASP-33b one of the few planets with such an offset found so far .
Our derived Bond albedo , A _ { B } = 0.369 \pm 0.050 , and heat recirculation efficiency , \epsilon = 0.189 \pm 0.014 , confirm again that he behavior of WASP-33b is similar to that of other hot Jupiters , despite the high irradiation received from its host star .
By connecting the amplitude of the phase curve to the primary transit and depths of the secondary eclipse , we determine that the day- and nightside brightness temperatures of WASP-33b are 3014 \pm 60 K and 1605 \pm 45 K , respectively .
From the detection of photometric variations due to gravitational interactions , we estimate a planet mass of M _ { P } = 2.81 \pm 0.53 M _ { \mathrm { J } } .
Based on analyzing the stellar pulsations in the frame of the planetary orbit , we find no signals of star-planet interactions .