Bibcode
Smith, A. M. S.; Csizmadia, Sz.; Van Grootel, V.; Lendl, M.; Persson, C. M.; Olofsson, G.; Ehrenreich, D.; Günther, M. N.; Heitzmann, A.; Barros, S. C. C.; Bonfanti, A.; Brandeker, A.; Cabrera, J.; Demangeon, O. D. S.; Fossati, L.; Harre, J. -V.; Hooton, M. J.; Hoyer, S.; Kalman, Sz.; Salmon, S.; Sousa, S. G.; Szabó, Gy. M.; Wilson, T. G.; Alibert, Y.; Alonso, R.; Asquier, J.; Bárczy, T.; Barrado, D.; Baumjohann, W.; Benz, W.; Billot, N.; Borsato, L.; Broeg, C.; Collier Cameron, A.; Correia, A. C. M.; Cubillos, P. E.; Davies, M. B.; Deleuil, M.; Deline, A.; Demory, B. -O.; Derekas, A.; Edwards, B.; Egger, J. A.; Erikson, A.; Fortier, A.; Fridlund, M.; Gandolfi, D.; Gazeas, K.; Gillon, M.; Güdel, M.; Hasiba, J.; Helling, Ch.; Isaak, K. G.; Kiss, L. L.; Korth, J.; Lam, K. W. F.; Laskar, J.; Lecavelier des Etangs, A.; Magrin, D.; Maxted, P. F. L.; Merín, B.; Mordasini, C.; Nascimbeni, V.; Ottensamer, R.; Pagano, I.; Pallé, E.; Peter, G.; Piazza, D.; Piotto, G.; Pollacco, D.; Queloz, D.; Ragazzoni, R.; Rando, N.; Rauer, H.; Ribas, I.; Santos, N. C.; Scandariato, G.; Ségransan, D.; Simon, A. E.; Stalport, M.; Sulis, S.; Udry, S.; Ulmer-Moll, S.; Venturini, J.; Villaver, E.; Viotto, V.; Walter, I.; Walton, N. A.; Wolf, S.
Bibliographical reference
Astronomy and Astrophysics
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2025
Journal
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0
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Description
Aims. We aim to observe the transits and occultations of WASP-33 b, which orbits a rapidly rotating δ Scuti pulsator, with the goal of measuring the orbital obliquity via the gravity-darkening effect, and constraining the geometric albedo via the occultation depth. Methods. We observed four transits and four occultations with CHEOPS, and employ a variety of techniques to remove the effects of the stellar pulsations from the light curves, as well as the usual CHEOPS systematic effects. We also performed a comprehensive analysis of low-resolution spectral and Gaia data to re-determine the stellar properties of WASP-33. Results. We measure an orbital obliquity 111.3‑0.7+0.2 degrees, which is consistent with previous measurements made via Doppler tomography. We also measure the planetary impact parameter, and confirm that this parameter is undergoing rapid secular evolution as a result of nodal precession of the planetary orbit. This precession allows us to determine the second-order fluid Love number of the star, which we find agrees well with the predictions of theoretical stellar models. We are unable to robustly measure a unique value of the occultation depth, and emphasise the need for long-baseline observations to better measure the pulsation periods.